When it comes to growing and caring for flowers, watering (including air humidity), fertilization, light, and the soil and pot (since these two are closely related, they are usually not separated) are, in my opinion, the four most crucial elements!
— Actually, soil and fertilizer are not the same thing! I won't go into detail. When studying soil, we usually focus on its aeration, water permeability, and surface chemical activity; while fertilizer focuses on the elements it can provide to the plant roots that can be effectively absorbed.

Here's a brief discussion of fertilization.

I. Signs that your homemade organic fertilizer is successfully made

Seeing many posts from fellow flower enthusiasts about making their own organic fertilizer, I often wonder how to tell when it's done. Actually, composting has certain techniques and requirements:
the most basic sign of complete decomposition is —————————— no odor whatsoever. Indeed, not at all smelly! Only a very faint earthy smell.
Even in summer, deep burial and fermentation takes at least 4-6 months.
Anything with an odor is not completely decomposed. For personal processing, it's impossible to achieve complete decomposition in just one or two months!

If there is obvious oiliness, it means that it is not completely fermented! This is because oils are made up of large molecules!

II. Why must it be thoroughly decomposed?

1. Because plant roots can only absorb small-molecule inorganic and small-molecule organic matter (although the definition/meaning of small-molecule organic matter is still somewhat controversial, as very simple carbon (nitrogen) compounds can often be considered inorganic, the most typical examples being urea and hydrocyanic acid, which have the same molecular formula but different molecular structures and are isomers; urea is considered organic, while hydrocyanic acid is considered inorganic...). Details such as the transport mechanisms of root hair surface cells will not be elaborated upon.
(Insectivorous plants also absorb matter by digesting and breaking down secretions (using various enzymes)...)

2. Regardless of the raw materials, what we need are the final elements! Therefore, the raw materials must be processed!
Soybeans, vegetables, and other processable raw materials can be thoroughly cooked until very soft, breaking down large molecules to medium-sized molecules to a certain extent. Then, various bacteria can break them down into smaller molecules—bacteria are less efficient at breaking down large molecules, it's very slow!
Remember, chlorophyll, cellulose, proteins, and other things that people think are good cannot be directly absorbed by plant roots. Plant roots prefer nitrates, sulfates, phosphates, amino acids, and various metal ions, while absorbing very little carbon.

III. Serious Consequences of Incomplete Decomposition

Incomplete decomposition has many major drawbacks:
1. It easily continues to ferment, causing localized excessively high soil temperatures (30-50 degrees Celsius), which can easily burn and kill the roots! Many flower enthusiasts' plants die inexplicably this way. Over 99% of beginners' plants wither due to root problems, mostly from overwatering that suffocates the roots, and others from homemade "fertilizer" that has further damaged the roots.

2. Incomplete fermentation results in a large amount of fungi in the soil, making it easy for seeds, cuttings, and plants to mold! The consequences are obvious. Incomplete fermentation leaves a large amount of undecomposed or partially decomposed organic matter in the soil, making it particularly appealing to bacteria and fungi… whereas thoroughly fermented soil consists mostly of small-molecule compounds that fungi and bacteria cannot directly utilize! ———————— Is the logic clear now?

Note: Any homemade organic fertilizer must still be diluted thoroughly, usually 10-50 times, depending on the type of flower, season, soil/air humidity, and plant condition. The basic principle is: apply fertilizer sparingly and frequently, and alternate between water and fertilizer.

Fourth,
for home gardening enthusiasts, it is not recommended to use leftovers, kitchen scraps, etc., as they contain too many bacteria that are human-related, have too high an oil content, and require too long a fermentation time.

The raw materials for homemade organic fertilizer should ideally not contain salt!

Two types are recommended:

(I) Plant-based raw materials
1. Fallen leaves
In the United States, many large cities (I lived in New York for more than half a year) have government-funded labor to collect fallen leaves, compost them, and then give them away or sell them to residents at a low price
. It is best to cover the fallen leaves with soil at least 40 cm! Unless it is tropical
, and each layer of fallen leaves should not exceed 5-10 cm. The fallen leaves and soil
should be covered alternately and composted for at least 6-12 months. Keep the soil moist, but do not overwater to prevent nutrient loss.
If there is a dedicated cement/tile composting pit, it is best to use it.
Main components: nitrogen
Secondary components: phosphorus, potassium, iron (the core component of chlorophyll is iron, just like human hemoglobin, because they have a common origin!)
Mainly used as nitrogen fertilizer, low concentration, not easy to damage the root system
. It should not be used too much during the flowering and fruiting period, because flowering and fruiting require a lot of phosphorus, potassium and sulfur.

2.
If using rotten fruit, seeds, seed coats, flowers, etc., the decomposition time needs to be slightly longer
, but the content of phosphorus, potassium, and sulfur will be much higher.

3. Soybean cake, soybean residue, etc.,
should be sealed and allowed to ferment for at least 3-6 months, depending on the defatting process. Inoculation with microbial cultures is recommended to accelerate fermentation until completely odorless.
The phosphorus, potassium, and sulfur content should be higher than that of leaf compost but lower than that of fruit compost.
Directly using soybeans or soybean products for composting is problematic because soybeans have a high oil content, resulting in a long fermentation time. For hobbyists, without proper microbial inoculation, the compost may remain smelly even after a year or several years.
Therefore, it is recommended to thoroughly cook and simmer the soybeans before fermentation to significantly shorten the fermentation time!

4.
Another method is to soak the grass blades after mowing the lawn in an extract for one hour. Do not soak them for too long, or they will smell bad!
Fresh grass blade extract is an excellent option.

5. Mushroom Culture Medium:
Mushroom culture medium has a very complex composition, and bacteria proliferate too quickly after harvesting. Furthermore, the original mushroom mycelium is almost entirely present in it. Not all fungi are the same; some break down large organic molecules into smaller organic and inorganic molecules, while others (especially fungi) do the opposite. Therefore, unless there is no other choice, it is generally not recommended to use mushroom culture medium as a fertilizer source or as a component of soil/culture medium for planting flowers.

(II) Animal-based raw materials
1. The biggest advantage of homemade organic fertilizer made from animal-based raw materials is its high phosphorus, potassium, and sulfur content! The low nitrogen content
makes it suitable for use before flowering and in the early bud formation stage. Phosphorus and potassium fertilizers are not suitable during flowering because they can cause premature bud and flower drop!
It is also suitable for the fruiting stage.

It is not recommended to use leftover food or kitchen scraps that come into contact with people, because there are too many pathogenic bacteria in them!

My preferred method is to collect snails from the pond in my neighborhood
, or you can buy them at the market. They need to be left to ferment, and after removing all mud and debris, they should be thoroughly washed and ready to use.
You can use a large paint bucket that can hold 30-50 kg of water. Wash it thoroughly and set aside. Fill the bucket with
3-5 kg ​​of snails, filling it with 60-80% water
and seal it, or cover it completely (recommended).
Because fermentation takes a long time, it easily produces a lot of gas, so even sealed containers need some ventilation (it doesn't smell good...).

If you find fly eggs or maggots, don't worry. As long as the container is well-sealed, they will all turn into fertilizer over time. :-)

The sign of success:
A fully cooked snail soup should be a dark black liquid (suspension), completely odorless, with black suspended matter
at the bottom, stirred before use.

(III) Animal excrement:
As mentioned before, human excrement and urine are not suitable!
The excrement of herbivores such as cow dung and sheep dung can be used, but
pig dung and human excrement and urine, which are high in nitrogen, are not suitable! (Omnivores)

Chicken and pigeon manure are also good, and they are very high in phosphorus!

The highest quality (solid) organic fertilizer is made from the fermented droppings of herbivores/birds!

(iv) Other
1. Sawdust
can be used, but it is quite complicated.
First, it must be thoroughly composted.
Second, the sawdust from different trees varies greatly. For example, the sawdust from gymnosperms such as pines, cypresses, and firs contains a large amount of resin (rosin) secretions, which have strong insecticidal properties and are also extremely damaging to plant roots! Some plant secretions are toxic, so caution must be exercised!

(V) Natural Organic Fertilizer/Nutritional Soil
1. Pond mud
is fertile, but often has strong stickiness and is not suitable for direct use alone. It is better
used as a base fertilizer in rural areas for seedling cultivation.

2. Pine needle soil
requires a leaf litter depth of over 10-20 cm. The soil beneath the leaves should be loose/dense and dark in color! Only soil layers 10-20 cm or thick should be used. Pine needles should not be used directly!
Trees with low resin content, such as larch, are preferable.

3. Peat
has good fertilizer effects, but due to environmental differences, there are also significant differences between varieties. It is not suitable for direct use alone, but can be mixed. Some varieties are also often quite sticky.

4. Bamboo leaf soil
is best! Take the sediment from under the bamboo leaves! It has moderate fertility, not too much, and is loose with low stickiness. However, it is not advisable to take the bottom layer of red/yellow mountain soil, etc.

5. Fallen soil
usually refers to the humus soil of broad-leaved deciduous forests other than pine, cypress and bamboo.
It is usually very good, but you should avoid trees with strong and harmful secretions and poisonous tree species
. Generally, you take the soil but not the leaves!

V. Raw Material Processing

1. Cook thoroughly!
Note: (Repeating) Regardless of the raw materials, we need the final element! Therefore, the raw materials must be processed!!!
Soybeans, vegetables, and other processable raw materials can be thoroughly cooked until very soft, breaking down large molecules to medium-sized molecules to a certain extent. Then, various bacteria can further break them down into smaller molecules—bacteria are less efficient at breaking down large molecules, it's very slow!!!
Remember, chlorophyll, cellulose, protein, and other things that people think are good cannot be directly absorbed by plant roots. Plant roots prefer nitrates, sulfates, phosphates, amino acids, and various metal ions, etc. Plant roots absorb very little carbon.
Example: During the Cultural Revolution, in Northeast China, to get results from leaders, they cooked piglets and buried them under trees; of course, the following year, the trees bore abundant fruit… But if they weren't cooked thoroughly, the effect wouldn't be the same…

2. Additives:
In addition, before the composting process is nearing completion, a small amount of ferrous sulfate or superphosphate can be added to increase the iron and phosphorus content, effectively multiplying their absorption.
Iron and copper are the most crucial metallic elements for plants. Chlorophyll contains iron (because chlorophyll and animal hemoglobin share a common origin!), but plants have difficulty absorbing ferric iron (Fe3+). Therefore, mixing ferrous sulfate with weakly acidic organic fertilizer can greatly increase absorption efficiency without polluting the environment!
However, copper generally does not need to be added specifically! Excessive copper content can easily cause pollution. Although it can kill insects (such as Bordeaux mixture made from lime and copper sulfate), it also damages the root system!

3. Misconceptions about ferrous sulfate:
Adding ferrous sulfate is not for adjusting pH (acidity/alkalinity) – In professional horticulture, pH adjustment commonly uses sulfur powder (also commonly used for disinfecting wounds from cuttings), limestone powder, etc., not ferrous sulfate. Here's a correction for a common misconception among beginners/enthusiasts: Ferrous sulfate is not a panacea! It should primarily be used to add iron, and only in a weakly acidic environment; it cannot be directly sprinkled on top! Furthermore, ferrous sulfate is not the best way to adjust pH because, although it can absorb hydroxyl groups (OH-), ferric hydroxide/ferric oxide is not beneficial to the soil! It can even be harmful to roots due to the high concentration of metal ions! Sulfur powder, on the other hand, reacts and absorbs chemically very slowly, resulting in a milder effect. Sulfur itself is one of the four essential elements for life (carbon, nitrogen, phosphorus, sulfur; hydrogen and oxygen, while not indispensable, are generally considered default elements (derived from water) and therefore not considered core elements).

VI. Use of Homemade Organic Fertilizer

1. **Important:** Dilute this product!!! Dilute!!! Dilute!!! Otherwise, it will damage the roots!!!
Generally, dilute 20-50 times, depending on the fertilizer requirements, robustness, and adaptability of different flowers.
For vegetables and fruits, a dilution of 10-20 times is acceptable.

Note that any fertilizer needs to be properly diluted. In most cases, if you are unsure, dilute it 20-50 times. It is better to be too weak than too strong. Apply fertilizer sparingly and frequently.
The soil must be loose and well-drained. Flowers/trees are best placed in high places with ditches to facilitate drainage and remove excess moisture from the ground.

2. For purchased solid organic fertilizer, it must be covered with soil before use to prevent rapid oxidation and loss of fertility, as well as to prevent it from being washed away by water!
Currently, the best solid organic fertilizer on the Shanghai market is from the Shanghai Academy of Agricultural Sciences. It is of high quality, pure, and free of impurities! It generally costs 20-30 yuan per bag, weighing 30-50 jin (depending on moisture content).
You can call to inquire (I receive dozens of bags every year, so I don't know the department or phone number).

VII. Some Common Questions
1. Nutrient Soil and Organic Fertilizer
Indeed, there are many nutrient soils/organic fertilizers available, but their quality varies greatly
. However, high-quality ones all contain a large amount of specialized bacteria/fungi (strictly speaking, yeast, etc., are not actually bacteria... it is the only single-celled fungus,
but that's another story). They are fermented under controlled conditions with high humidity and constant temperature, so they only need about three months. Some ferment for 4-6 months, but for homemade products, at least 6 months is recommended. There's no other way; if there's a foul odor, it's not ready yet.

Actually, nutrient soil and organic fertilizer are not entirely the same thing.
The best raw materials for organic fertilizer are bird droppings such as chicken, duck, and pigeon droppings. The next best are the droppings of herbivores such as sheep, cow, and rabbit droppings. Then there are pig droppings and human excrement. The principle is not repeated here.
In the actual process of making organic fertilizer at home, a small amount of ferrous sulfate (must be added in a weakly acidic substrate, otherwise it will easily oxidize and become ineffective) and potassium dihydrogen phosphate are usually added. Bird droppings do not need to have phosphorus and potassium added.

2.
Note on microbial inoculum: Yeast should absolutely not be used as the main inoculum for composting, because yeast mainly performs preliminary and simple decomposition of sugars (disaccharides and monosaccharides such as lactose and glucose), and is far from meeting the requirement of decomposing raw materials into small-molecule inorganic substances!

Adding yeast to compost is useless. There are countless species of bacteria and fungi in the world, and you can't just add any one. Otherwise, wouldn't we be able to eat our athlete's foot (caused by fungi) directly? ... (Mushrooms and shiitake mushrooms are also fungi, and steamed buns are fermented with yeast (generally considered the only single-celled fungus)...)

Composting requires not just a single strain of bacteria, but a whole community of microorganisms!
These microorganisms (bacteria and fungi) can be obtained from river/pond water or fertile soil.

3. Composting fertilizer requires patience, and so does growing flowers. In a materialistic society, people are restless and lack patience. Learning patience is key to understanding the true meaning of life. To put it more bluntly, it's how you grasp the secrets of investing and quickly become wealthy... :-)

4. Adding orange peels to compost is useless; it has little effect on removing odors.

5. In theory, any raw material can be used. The key is to determine what components of fertilizer are needed, and then decide which raw material to use, and also which raw material is readily available! The composting time varies greatly depending on the raw material, as explained in my original post.

6. Continuous Crop, Fallow, Intercropping, and Crop Rotation
: Continuous Crop – Planting the same variety of plants in the same soil (like potting soil) for many years can easily deplete certain elements, which are difficult to recover. A major drawback is that it can intensify pests and diseases!
Fallow – To avoid the negative consequences of continuous cropping, plant two crops and leave one, or three crops and leave one,
fallowing is common in Europe.
Intercropping – Planting corn and soybeans in alternate rows fully utilizes sunlight and nutrients, mitigating
pests and diseases. Crop Rotation – Planting different crops every other year avoids depletion of certain elements in the soil and prevents the rampant spread of pests and diseases. Different crops have different pests and diseases, especially plant species with large taxonomic differences. For example, the pests and diseases of gramineous crops such as rice, wheat, and corn are significantly different from those of soybeans and cotton, with only some commonalities.

Fallowing and crop rotation are primarily intended to allow the land to recover and regenerate, and to prevent severe outbreaks and outbreaks of pests and diseases.
The problem of continuous cropping is very serious in rural China, resulting in pesticide and fertilizer usage per unit area being 3-10 times higher than the average level in developed countries, while average yields are significantly lower.

Therefore, potting soil needs to be replaced at least annually. It's not recommended to break up the root ball/clove during repotting, as this can severely damage the roots. However, it's necessary to loosen the soil appropriately! Add new soil, replacing some of the old soil, and add base fertilizer, using more organic fertilizer and less chemical fertilizer—Note: This doesn't mean eliminating chemical fertilizer altogether, but rather using it sparingly. Chemical fertilizers are far more effective than organic fertilizers for high-yield crops like vegetables and fruits. Organic fertilizers should play a regulating and finishing role!

Making your own compost is environmentally friendly, clean, cultivates patience, and allows you to learn a lot about organic chemistry and microbiology.
Thoroughly decomposed organic fertilizer truly has no odor whatsoever; my "snail soup" is a black, odorless suspension.
The organic fertilizer sold by the Shanghai Academy of Agricultural Sciences is of very high quality and also has absolutely no unpleasant smell! It generally costs around 25 yuan per bag, with each bag containing 30-50 jin (15-25 kg), and it's truly excellent.

Simple methods for preventing and controlling diseases and pests in home gardening

Simple methods for preventing and controlling diseases and pests in home gardening

Here are a few methods that every household has and everyone can do.

1. Tea seed cake water: For soil pests, pouring tea seed cake water into the soil will cause the pests to emerge from the soil and die.

Preparation method: Crush the tea seed cake, and soak 1 kg of tea seed cake in 10-15 kg of water. In summer, soak for 1 day.

In spring and autumn, apply the solution every 1-2 days, rubbing it a few times to remove the residue before watering the soil around the plant roots.

2. Ash water: Kills aphids, leaf beetles, thrips, mirid bugs, etc.

Preparation method: Soak 1 kg of tobacco leaves or shredded tobacco in 10 kg of boiling water, cover and wait until it is not too hot to handle. Rub the tobacco leaves and shreds several times, then remove the leaf residue. To enhance the effect, lime water can be added. When using, filter out the residue and add water to about 35 kg. Spray the solution onto the plants.

Alternatively, soak 50-100 cigarette butts in 200-3000 ml of water for 24 hours, repeatedly crush them, filter out the residue, and then spray.

An even simpler method:

3. Soapy water: Effective against small insects such as aphids and scale insects.

Preparation method: Add 1 part laundry soap to 50-60 parts water. Cut the soap into thin slices and place them in a container. Pour boiling water over the soap and stir until dissolved. After cooling, it is ready to spray.

4. Laundry detergent water: Same as above

Preparation method: Add 1 part water to 200-300 parts water, dissolve evenly, and then spray.

5. Egg oil emulsion: Best used for small pests, applied at midday on sunny days.

Preparation method: Take one egg white (remove the yolk), add 200 ml of water to make egg white water, then add 2-3 ml of cooking oil and shake up and down. When no oil droplets are visible on the surface, it is ready for use and should not be stored.

6. Batter water: For mites (red spider mites), spray under sunlight in hot weather.

Preparation method: Mix 1 part flour with 50-60 parts water to moisten the flour first, then pour boiling water over it to cook it and dilute it. There should be no lumps. Spray it at noon after it cools down.

Six methods to eliminate insects and ants in flower pots

(1) When small flying insects appear in flower pots, use three or four cotton stalks, soak them thoroughly in dichlorvos (DDVP) until they don't drip, and then insert the ends of the stalks into the soil around the plant. The flying insects will be eliminated.
(2) Laundry detergent: Dissolve one tablespoon of laundry detergent in 4 liters of water and spray the leaves every two weeks to completely eliminate whiteflies and bacteria.
(3) Milk: Mix 4 cups of flour and half a cup of milk into 20 liters of water, filter with gauze, and spray on the leaves to kill ticks and their eggs.
(4) Beer: Pour beer into a shallow dish placed under the soil of the flower pot, and snails that crawl in will drown.
(5) Garlic: Crush a head of garlic and mix it with one tablespoon of pepper powder into half a liter of water. After an hour, spray it on the leaves to prevent rodent infestation.
(6) When ants appear in flower pots, you can soak cigarette butts and tobacco in hot water for one or two days. When the water turns dark brown, sprinkle some of the water on the flower stems and leaves, and dilute the rest before watering the flower pots. This will kill the ants.

Clever ways to get rid of earthworms in flower pots

① Slowly place the flowerpot into a bucket of clean water, ensuring the water level is above the surface. After about an hour, earthworms will emerge from the soil and enter the bucket, at which point they can be removed.
② First, thoroughly water the flowerpot. Then, crush 3-4 cloves of garlic, dilute with water, and pour the mixture into the pot. After a while, earthworms will emerge from the soil, which can then be removed with tweezers. ③ You can soak 100 grams of fresh maple leaves in water for 48 hours. Remove the leaves, and pour the leaf juice into the flowerpot. Earthworms will emerge from the soil when removed.

Method 1 for controlling snails 
: In spring, before the snails climb trees, apply sticky insect glue around the tree trunk. This method also controls red spider mites, white spider mites, bridge-building worms, green mirid bugs, and all other pests that climb trees by crawling (the sticky insect glue is produced by the Hebei Academy of Agricultural Sciences and is available at the Shenzhou Trade City Science Popularization Center). It is very low-cost, highly effective, and lasts for three months. It is non-toxic and pollution-free.
Method 2: For chemical control, you can use "Snail Killer." 
Find a small bowl, pour in about half a bowl of beer, and place it in areas where snails are likely to appear at night. The next morning, wait and see! A bunch of snails will be submerged in the beer and drown, turning white! Leave it for two to three days until the beer smell fades before replacing it with fresh beer.

The way to treat spider mites is to rinse the flowers with water, especially the infected areas, several times. Spider mites dislike dampness.

Spray diluted milk. It's better to be too diluted than too concentrated. This can also kill spider mites.

The simplest home remedy for killing spider mites: Dilute commercially available miticide soap with water 200-300 times, spray the affected plants, just enough to moisten them slightly, but don't use too much. You can try it!

Common diseases include viral diseases, white mold, and leaf spot. Prevention should focus on improving cultivation conditions and strengthening daily maintenance. In the early stages of disease, spray viral diseases with a 1000-fold dilution of aspirin; for white mold, use chloramphenicol injection (1 vial diluted in 1 kg of water) to drench the affected plants once daily for two consecutive days; for leaf spot 
, spray with a 2000-fold dilution of penicillin every two days for 3-4 consecutive days for good results. Major pests include scale insects, aphids, and spider mites. For scale insects, remove them one by one with a toothpick or toothbrush if there are only a few; for large infestations, spray with a 500-700-fold dilution of malathion.
For aphids, spray with a 500-fold dilution of 10% aphid-killing wettable powder produced by Jiangsu Kesheng Group; this method is very effective.

To treat aphids: Mix 5 grams of laundry detergent with 1200 grams of water, stir thoroughly, and spray. Repeat every 3 days for 2-3 times. The kill rate can reach 100%.
To treat snails: Pour beer into a shallow dish and place it on the ground or in potting soil. Snails will be attracted by the aroma and crawl into the dish to drown.
To treat ants: Crush garlic cloves and bury them in 3-4 holes in the potting soil. After 2-3 days, the ants, earthworms, and nematodes in the soil will disappear.
To treat spider mites: Light a mosquito coil containing pyrethrum and place it in the orchid pot. Seal the pot with a plastic cover and fumigate for 1 hour to kill the eggs and adults.
To treat scale insects: Soak 1 jin of mature neem fruit in 1 kg of water for more than 1 month, then extract the juice for later use. In late spring and early summer, use a 1:1000 solution for prevention; if small scale insects are found, use a 1:500 solution for treatment and killing, once every 5 days, for a total of 3 times, to kill the small scale insects.

Tobacco: Efficacy: Nicotine and nicotine in cigarettes can control pests such as aphids, spider mites, stink bugs, and ants.
Preparation: ① Soak 40g of tobacco leaves or stems in 1000ml of water for 24 hours, filter, then dilute with an equal amount of water, and add 2-3g of laundry detergent to dissolve (if using shredded tobacco, the concentration can be higher; adding laundry detergent helps with adhesion and also has an insecticidal effect); ② If a weighing device is not available, soak several cigarette butts (without paper) in about 30 times their volume of water until the water turns yellowish-brown, then add a small amount of laundry detergent to dissolve;
Use: Use after filtering. ① Spray both sides of the leaves; ② For severe pest infestations, immerse the affected parts of the plant in the tobacco water for 1-3 hours, while simultaneously soaking the potting mix. This will effectively kill pests on the leaves and in the soil; ③ Remaining tobacco water can be poured into ant nests or sprinkled around the pot to kill ants; ④ Burying unsoaked cigarette butts in the soil can control small flying insects. 
Precautions: ① Contains nicotine, so do not add vinegar, as this will weaken the insecticidal effect; ② If adding laundry detergent, rinse with clean water the day after spraying (or immediately after soaking); ③ If primarily used for scale insect control, it is best to add laundry detergent, or use laundry detergent alone.

Garlic: Benefits: Controls aphids, spider mites, scale insects, nematodes, and powdery mildew. 
Preparation: Take a few cloves of purple-skinned garlic from northern regions, peel and crush them, then dilute with 10-20 times the amount of water. After 2-4 hours, filter out the residue. 
Uses: ① Spray the juice onto the leaves; ② Pour the residue and remaining juice into the pot to control nematodes and scale insects.
Precautions: Garlic juice has a certain viscosity; to prevent dust accumulation, rinse the leaves after several days.

Chives: Efficacy: Can control pests such as aphids and spider mites, especially effective against aphids.
Preparation and Use: Crush 500 grams of chives, add 1250 ml of water, soak for 24 hours, filter, and spray the supernatant three times every other day.

Onion: Efficacy: Controls pests such as aphids and spider mites, especially effective against aphids.
Preparation and Use: ① Soak 20 grams of onion scales in 1000 ml of water for 24 hours before use. Spray 2-3 times consecutively within a week; ② To ensure full extraction of active ingredients, it can be chopped or crushed before soaking. Filter before use.

Pointed red chili peppers (dried red chili peppers): Efficacy: Controls aphids, spider mites, whiteflies, stink bugs, and other pests. 
Preparation: ① Thoroughly dry in the sun and grind into a fine powder; ② Add 50g of chili powder to 1kg of water, boil for 10 minutes, then cool and filter; ③ Take an appropriate amount of dried chili peppers, add 20 times the amount of water, boil for 20 minutes, cool, and filter; ④ Add 250g of dried chili seeds to 2.5kg of water, boil for 30 minutes, cool, and filter.
Usage: ① Spray the leaves with water, then spray with the powder. A small amount of coarse powder can be sprinkled on the surface of the potting soil; ② Spray the leaves and potting soil.

Wood ash: Efficacy: Controls aphids.
Preparation and use: Soak 1 part wood ash in 5 parts water for 24 hours, filter, and spray. Use this method for prevention, generally once a month. It is best to alternate between different methods.

I haven't used wood ash in the above methods, mainly because it's alkaline and not very suitable for northern regions. I've used the other methods for a year without any side effects or pest infestations, but this is just my personal experience and is for reference only. Even so, I want to say this upfront—if you follow these methods and something goes wrong, don't blame me! Additionally, beer, laundry detergent solution, baking soda, sulfur powder, and many traditional Chinese medicines are also effective in preventing and controlling pests and diseases, but I haven't used them extensively enough; I'll discuss them later.

Homemade Insecticides:
Laundry Detergent Solution: Mix 2 grams of laundry detergent with 500 grams of water to form a solution. Add one drop of cooking oil and spray onto the plants to kill insects. This can kill aphids, scale insects, spider mites, green tussock moths, white butterflies, and whiteflies. For plants with tuberous roots (such as peonies and dahlias), bulbs (such as lilies and lycoris), or fleshy roots, which are susceptible to nematode infestations, a 1000-fold diluted laundry detergent solution can be poured around the base of the plant. 
Soap Solution: Dissolve soap in hot water at a 1:50 ratio and spray. Soap can clog the respiratory organs of pests, leading to their death; this is effective against aphids and scale insects. 
Tobacco Solution: Tobacco contains nicotine, which has a strong contact killing effect on aphids, spider mites, and ants. It also has fumigation and stomach poison effects. Take 20 grams of tobacco powder or shredded tobacco, add 500 grams of water and soak for 24 hours, then filter. Add 500 grams of 2% soapy water to the filtrate and spray it on the leaves with pests. Alternatively, spray the filtrate directly onto the potting soil and around the bottom of the pot without adding soapy water to kill soil pests.
Garlic liquid: To treat powdery mildew and black spot on roses, take 30 grams of garlic, crush it, add 500 grams of water, stir well, filter, and spray the filtrate on the leaves once a day for 3-4 days. Alternatively, you can apply the garlic liquid directly to the leaves with a brush or toothbrush. Crushing garlic and sprinkling it into the potting soil can also kill earthworms, ants, and nematodes. 
Scallion liquid: Take 50 grams of scallions, crush them into a paste, add 50 grams of water, soak for 12 hours, filter, and spray the filtrate several times a day for 3-4 days to treat aphids and other soft-bodied pests as well as powdery mildew.
Ginger solution: Crush fresh ginger into a paste, add 20 times the amount of water, soak for 12 hours, filter, and spray with the filtrate to control leaf spot, sooty mold, rot, black spot, etc., and also to control aphids, spider mites, and leaf miners. Sichuan
pepper solution: Boil 50 grams of Sichuan pepper in about 500 grams of water in a pot until reduced to 250 grams of liquid. Dilute with 6-7 times the amount of water before spraying to control whiteflies, aphids, and scale insects. 
Citrus peel solution: Soak 50 grams of citrus peel in 500 grams of water for 24 hours, filter, and spray the filtrate on the leaves to control aphids, spider mites, and leaf miners. Pour the solution into the soil to control nematodes. Alternatively, soak 1 part citrus seeds in 5 parts water for 4-5 days, then soak flower seeds in this solution for 10 minutes to control various pests.
Bitter gourd leaf extract: Crush 100-200 grams of bitter gourd leaves with water, add an equal amount of lime, stir well, and water the roots of seedlings to control cutworms.
Tomato leaf extract: Crush 50 grams of fresh tomato leaves, add 150 grams of water, soak for 6 hours, filter, and spray the filtrate to control aphids, spider mites, etc., and also repel flies.
Chili pepper extract: Boil 50 grams of chili peppers in 10 times their volume of water for 20 minutes, filter, and spray the filtrate to control aphids, spider mites, stink bugs, etc., and watering the soil can control ground beetles. 
Castor bean leaf powder: Dry castor bean leaves and stems, grind them into powder, and apply to the soil to control grubs.
Oleander extract: Chop 50 grams of oleander branches and leaves, add 100 grams of water, boil for 20-30 minutes, remove the residue, and spray the clear liquid to control aphids and whiteflies, and watering the soil can control nematodes. However, be aware that oleander is highly toxic, and care should be taken to prevent accidental ingestion by humans and animals. 
Rice vinegar solution: Rice vinegar is rich in organic acids, which have a good inhibitory effect on pathogens. Spraying the leaves with a 150-200 times diluted rice vinegar solution every 7 days for 3-4 consecutive times can prevent powdery mildew, black spot, and downy mildew.
Baking soda solution: Take 5 grams of baking soda (also known as sodium bicarbonate), dissolve it in a small amount of alcohol, then add about 1000 grams of water to make a 0.5% concentration solution. Spraying this solution on the plants can prevent powdery mildew.
Mosquito coils: After lighting a mosquito coil, hang it on the infested plant, cover the plant and pot with a plastic bag, and the pests will be eliminated after 1 hour.
Eucalyptus oil: Eucalyptus oil diluted 400-500 times with water can kill aphids. 
Mothballs: Crush mothballs and place them in the potting soil to control underground pests.
Potassium permanganate (commonly known as potassium permanganate): Potassium permanganate solution can prevent powdery mildew on flowers. In the early stages of the disease, spray with a 0.1%–0.2% solution once every 7 days, for 2–3 consecutive applications. The effect can reach over 92%. (Note: Avoid direct contact with solid potassium permanganate with your hands.)

Diseases and pests of domestic plants and their control   .

1. Piercing-sucking pests 
　　are insects that use their piercing-sucking mouthparts to penetrate plant tissue and suck plant sap. Most piercing-sucking pests are small in size, but they often occur in large numbers and reproduce rapidly. The main pests of this type that damage houseplants include:
Aphids: Many species, mostly around 2 mm in length, with colors such as green, gray, black, and orange. They usually concentrate on tender buds, leaves, and branches, sucking sap and causing the affected parts of the plant to wither and deform. Aphids also secrete honeydew, polluting the plant and inducing diseases such as sooty mold.
Scale insects: Many species, small in size. Many species primarily feed by fixing themselves in one spot and sucking sap. They are covered with a waxy scale, making pesticide spraying difficult to be effective.
Spider mites (red spider mites): Tiny, less than 1 mm in length. They mostly suck sap from the underside of leaves, often causing leaf discoloration and even curling.

2. Leaf-eating pests 
　　: "Caterpillars" – mainly the larvae of moths, butterflies, and bees: There are two types of damage. One is direct gnawing on plant leaves, causing notches and holes; the other is leaf-rolling damage, where they first spin silk to stick to the leaves and then eat them from within. 
　　"Beetles" – Coleoptera adults and larvae: mainly leaf beetles and scarab beetles. Both adult and larval leaf beetles can eat leaves; adult scarab beetles eat leaves, while their larvae are underground pests.

3. Cutworms (root pests  )
　　: The larvae are dark in color and burrow in the soil, damaging plant roots. They may also emerge at night to bite off the root collar, causing plant death, or gnaw on parts of the stems and leaves. 
White grubs (ground beetle larvae): These are white scarab beetle larvae that burrow in the soil and damage plant roots.
Snails and slugs: They burrow underground during the day or in other dark, damp places, and become active at night or in the early morning or late evening, feeding on plant branches and leaves.

Diseases
1. Foliar Diseases Foliar
　　diseases are a common type of disease in houseplants, including leaf spot, black spot, anthracnose, scab, gray mold, powdery mildew, sooty mold, etc. Their common characteristic is the appearance of lesions on the leaves, sometimes even with a mycelial layer (such as powdery mildew, sooty mold, and gray mold). Severely infected leaves will gradually discolor, wither, and fall off. Some foliar diseases can also infect tender shoots and flower buds. Plants weaken due to disease, and their ornamental value is also affected.

2. Root and Stem Diseases: 
　　Among root and stem diseases, rot is the most impactful, causing plant death. Besides pathogen infection, root or stem rot is often related to improper cultivation management. For example, overly wet substrate can cause root rot; sunburn, high temperature damage, or frost damage to young branches can easily induce stem rot; and an overly humid environment can also easily induce stem rot.

Pest and Disease Control:
Pest and disease control should emphasize "prevention first, integrated management." 
⑴ Do not bring diseased or pest-infested plants home; when propagating, use disease-free plant material. 
⑵ Improve and strengthen cultivation management to ensure robust plant growth and enhance their resistance to pests and diseases. 
⑶ Improve the environmental conditions of the plants, such as improving ventilation and light penetration, which can reduce the likelihood of some scale insects, aphids, and other pests, as well as many diseases; loosening the soil and controlling watering can reduce the possibility of root rot.
⑷ Observe frequently; if you find any pests or signs of disease in your houseplants, deal with them as soon as possible. 
⑸ Try to remove pests and diseases manually, or spray homemade "pesticides" to treat and kill them. For example:
use a soft brush to remove scale insects attached to the plant's branches and leaves;
wash aphids and spider mites with tobacco water or very diluted soapy water;  
prune and remove withered or diseased branches, leaves, and flowers, and promptly remove fallen dead branches and leaves to prevent the spread of pathogens.
(6) Based on the type of disease (insect) that has occurred, purchase targeted, low-toxicity pesticides from the flower and tree market and apply them according to the instructions.
(7) For plants that are prone to or frequently suffer from diseases, fungicides should be used for prevention before the usual disease season.