Fertilizing Methods and Precautions for Flowering Plants

The two-sided nature of top dressing: Like repotting, top dressing also requires the right conditions. You need to consider not only the season but also how the plant is growing, and take both into account. Applying it when it is actually needed will promote growth, flowering and fruiting; conversely, applying fertilizer blindly without considering the conditions can easily backfire, ranging from affecting growth and causing fertilizer damage to, in severe cases, killing the plant outright.

Top dressing condition: Check the temperature:

Generally speaking, a temperature between 15 and 30 degrees is suitable for top dressing; but when the temperature stays below 15 degrees or stays above 30 degrees, top dressing should be done with caution. If the temperature is too low or too high, the risk after top dressing increases, and fertilizer damage is likely.

Top dressing condition: Check the plant's growth state:

1. Under normal circumstances, the situations suitable for top dressing include the growth period (mainly nitrogen fertilizer); the bud stage, the fruiting stage, and the post-flowering growth period of bulbous or herbaceous perennial plants (mainly phosphorus and potassium fertilizer).

2. If the plant has just been transplanted and is in the state of recovering from transplant shock, do not give it top dressing too early. At this time, top dressing will actually do more harm than good and affect its recovery.

In short, a simple way to describe it is “no new leaves (buds), no top dressing.”

Top dressing methods:

1. General method: For the vast majority of potted plants, when top dressing, dig open the surface soil at the edge of the pot, put the fertilizer in directly, then cover it with soil and water thoroughly. This method is suitable whether the fertilizer is water-soluble or sparingly soluble in water.

2. For water-soluble fertilizers, they can also be mixed and dissolved with part of the water, then sprayed directly on the plant leaves (foliar fertilizer), or dissolved directly in water and applied along with the water.

The principle of top dressing: apply thin fertilizer frequently. Thin fertilizer: when you have not yet mastered the appropriate amount, keep the concentration as low as possible (follow the instructions on the packaging as much as possible; if the seedling is very small, reduce it as appropriate).

Frequent application: this means fertilizing often. Small, frequent meals are most beneficial to plant growth. But frequent also needs moderation. For continuous top dressing, leave at least more than a week between applications. You cannot use this fertilizer today and another fertilizer tomorrow. Top dressing too frequently, over the long term, will exceed the plant's tolerance limit and likewise cause fertilizer damage; also do not supplement too much fertilizer at once and then give none for a long time. Feeding it too full and then letting it starve for a long time is also not advisable.

Special cases:

1. For plants in full bloom, during this period they are very sensitive to water, fertilizer and environmental changes. Generally, for most plants that flower and fruit regularly, top dressing is basically not needed during full bloom; but for herbaceous flowers that bloom year-round, such as petunias, geraniums, dianthus and moss rose, top dressing can still be given during full bloom.

2. The top dressing methods described above are suitable for potted plants, especially the point about checking the temperature. Once the temperature is unsuitable (too cold or too hot), it is best not to top dress; but for plants grown in the ground, the temperature requirements are not so strict and can be relaxed appropriately. You can simply judge by the plant's growth whether top dressing is possible.

Summary complete.

Supplement 1: Timing of top dressing (provided by the gardening friend Huashuyu):

Fertilizing is best not done at noon in summer or autumn. For foliar fertilizer, it is best applied in the afternoon when there is no direct sunlight or in the evening; otherwise the fertilizer sprayed on the leaf surface evaporates too quickly, the leaves do not absorb it fully, and it can easily cause sunburn on the leaves.

Precautions for fertilizing flowers

Precautions for fertilizing flowers in spring

How should flowers be fertilized in spring? What should be noted in spring flower care?

Right now is the time of warm spring and blooming flowers. As the saying goes, the whole year's work depends on a good start in spring. Flower growers all hope that this year's flowers will bring substantial economic benefits. Therefore, doing a good job in field management of flowers is very important. Below, I will talk about what needs attention when fertilizing flowers. Experts point out that fertilizing flowers should follow the "three observations." What are these "three observations"?

First, observe the season. In winter, temperatures are low and plant growth is slow. Most flowers are in a state of stagnant growth, so fertilizer is generally not applied; spring and autumn are the peak growth periods for flowers. Root, stem and leaf growth, flower bud differentiation and young fruit swelling all require relatively more fertilizer, so top dressing should be appropriately increased; in summer, temperatures are high, water evaporates quickly, and it is also a vigorous growth period for flower plants, so the concentration of top dressing should be low, but the frequency can be higher.

Second, observe the variety. Different varieties of flowers have different fertilizer requirements, so different fertilizers should be applied. For example, osmanthus and camellia like pig manure and dislike human feces and urine; southern flowers such as rhododendron, camellia and gardenia avoid alkaline fertilizers; flowers that need heavy pruning every year require a larger proportion of phosphorus and potassium fertilizer to help sprout new branches; foliage-focused flowers can lean toward nitrogen fertilizer; fruit-focused flowers should have watering appropriately controlled during the flowering period; bulbous flowers should be given more potassium fertilizer to help the bulbs plump up.

Third, observe the growth condition. Especially for potted flowers, fertilization should be based on growth condition to determine the amount. Adhere to the principle of "four more, four less, four no": four more means apply more when flowers appear yellow and thin, apply more before sprouting, apply more when forming buds, and apply more after flowering; four less means apply less when growing vigorously, apply less when sprouting, apply less when flowering, and apply less during the rainy season; four no means do not apply when leggy, do not apply when newly planted, do not apply in the height of summer, and do not apply during dormancy.

Watering

Watering in spring is key to growing potted flowers well. Because spring weather is relatively dry and air humidity is low, if the amount of water is too small, it will cause yellow leaves and leaf drop and affect the growth and development of flowers; watering too much will cause flower buds to drop or roots to rot, or even death.

How to judge whether a potted flower needs watering: If the color of the surface of the potting soil is brownish red, and pressing the surface of the potting soil with a finger feels soft and moist, and tapping the pot wall with a finger gives a muddy, dull sound, then the potting soil is moist and does not need watering; if the color of the surface of the potting soil becomes lighter and whitish, and pressing the surface of the potting soil with a finger feels hard, and tapping the pot wall gives a crisp, loud sound, then the potting soil is on the dry side and needs watering.

Frequency, timing and amount of watering for potted flowers

After the beginning of spring, temperatures start to rise and flowers enter their growth period, so the amount of watering should gradually increase. Generally, flowers should be watered once every 2 to 3 days, and later, as temperatures rise, gradually increase to once a day. By the high-temperature stage in July, water twice a day. Watering time is best between 10 a.m. and 4 p.m.

Different types of flowers have different habits and quite different water requirements. Moisture-loving flowers such as ferns, orchids and begonias should be watered more; drought-loving flowers such as crassulaceae, cactaceae and agavaceae should be watered less; bulbous flowers should not be watered too much.

Different growth and development stages require different amounts of water. Flowers entering the growth period from dormancy should be watered gradually more; flowers in the vigorous growth period should be watered more; water should be withheld before flower bud differentiation, during the seedling-hardening stage and before repotting; water less before flowering and during the fruiting stage, and water appropriately during full bloom; for newly potted or newly repotted flowers, the first watering must be thorough.

Different potting mixes have very different water-holding capacities, so the amount of watering should also differ. Sandy, loose soil has poor water retention and should be watered more; heavy clay soil has strong water retention and should be watered less.

The amount of watering also depends on the size and material of the pot. If the pot is small, the potting soil dries quickly and the frequency of watering should be increased; a large pot is the opposite. Clay pots are loose in texture and have good permeability, and the water lost through evaporation from the pot wall is even more than the water consumed by the flowers, so more watering is needed; ceramic pots, glazed pots and purple clay pots are fine and dense in texture and have poor permeability and air permeability, so less watering is needed; plastic pots are impermeable to water and air, so even less watering should be given.

Water quality

Rainwater, pond water and river water are most suitable. Generally, tap water can also be used for flowers, but it is best to let the tap water sit for 1 to 2 days before use.

Watering methods

Soaking method: Immerse the pot in a basin of water and let water seep into the potting soil through the drainage hole at the bottom until the potting soil is completely soaked. This method is mostly used for newly potted flowers and when sowing and raising seedlings in pots, to prevent external watering from washing away the potting soil or washing the seeds out of place and affecting seedling emergence.

Watering can method: Use a watering can to pour water directly onto the pot surface. This method is commonly used for relatively large flowering trees and shrubs.

Sprinkling can method: Use a watering can to sprinkle water on the leaf surface of the plant and the pot surface. This method is commonly used for newly potted seedlings, cuttings and foliage plants. But some flowers are especially sensitive to water. For example, gloxinia, calceolaria and begonia have relatively thick fuzz on the leaf surface, and after spraying, the water does not evaporate easily and the leaves rot easily; after the leaf buds at the top of the corm of cyclamen and the flower buds of African daisy are touched by water, they easily rot and wither, so spraying should not be used. For flowers in full bloom, water should also not be sprayed too much, otherwise it easily causes petal mildew or affects fertilization and lowers the seed-setting rate.

Fertilizing

Fertilizing according to the type of flower

Different types of flowers require fertilizers of different properties. The types of fertilizer applied should be reasonably matched, otherwise nutrient deficiency symptoms easily occur. Green foliage plants, such as monstera, spider plant, asparagus fern and sago palm, are generally mainly given nitrogen fertilizer, which can promote branch and leaf growth and deep green color; colorful foliage plants, such as coleus, caladium and dieffenbachia, besides nitrogen fertilizer, also need additional phosphorus and potassium fertilizer, otherwise the leaves will become leggy, the markings will disappear and the colors will be dull; flowering and fruiting ornamental flowers, such as large-flowered pansy, calendula, petunia and ornamental pepper, should be given complete fertilizer, with more nitrogen fertilizer at the seedling stage and more phosphorus fertilizer during flower bud differentiation, bud formation and the early flowering stage, so as to promote both abundant flowers and fruit; flowers that bloom multiple times a year, such as Chinese rose, jasmine and Aglaia odorata, are mainly given phosphorus fertilizer to promote repeated flowering; bulbous flowers are given more phosphorus and potassium fertilizer to help the bulbs develop; southern flowers that prefer acidic soil, such as rhododendron, camellia, gardenia, bromeliads and ferns, avoid alkaline fertilizers and should be given acidic fertilizers such as ammonium sulfate and superphosphate, and when necessary, ferrous sulfate should also be added to adjust the soil pH value to ensure abundant flowers and lush leaves.

Fertilizing methods and amounts

In spring, fertilizing potted flowers can generally use two methods: base fertilizer and top dressing:

Fertilizer applied into the soil before planting or potting flowers is called base fertilizer. For flowers that need potting or repotting in spring, some base fertilizer can be applied along with potting or repotting. Base fertilizer is generally mainly organic fertilizer, such as poultry and livestock manure, bean cake, compost and bone meal, and must be fully decomposed before use. The amount of base fertilizer should not exceed 20% of the total potting soil. It can be mixed with the potting mix and applied, or placed at the bottom of the pot or around the pot. The plant roots must never rest directly on the base fertilizer at the bottom of the pot; a layer of soil should be used to separate the roots from the base fertilizer.

Fertilizer that needs to be replenished at any time during the growth period of flowers is called top dressing. Top dressing is mostly liquid fertilizer, which is beneficial for soil absorption and root use. Top dressing follows the principle of "thin fertilizer, frequent application," and both organic and inorganic fertilizers can be used. For organic fertilizer, usually decomposed bean cake water or sesame paste residue water can be used. When using it, dilute with water, and the concentration should not exceed 5%. Because the roots of potted flowers in early spring are relatively tender, encountering strong fertilizer or undecomposed organic fertilizer easily causes damage, leading to yellowing and scorching of leaf edges. So at first it should be applied once every 10 to 15 days. As temperatures rise and plant growth increases, the frequency of fertilization should gradually increase to once every 7 to 10 days, and the fertilizer solution concentration should also gradually increase to 10% to 15%. Adding 10 grams of ferrous sulfate to each kilogram of bean cake, adding water and fully decomposing it gives alum fertilizer water. Alum fertilizer water is mostly used for acid-loving flowers and can make plant leaves deep green. Inorganic fertilizers commonly include urea, ammonium sulfate, superphosphate and potassium sulfate. When using them, attention must be paid to concentration, generally controlled at 0.1% to 0.5%, to avoid damage caused by too high a concentration.

Spraying a chemical fertilizer solution on plant leaves so that it is absorbed and used by the plant through the stomata is called foliar top dressing. Foliar top dressing is usually used during the vigorous growth period of flowers or when a certain nutrient element is lacking. Generally, it can be absorbed by the plant 4 to 5 hours after spraying, 50% to 75% can be absorbed within 24 hours, and the fertilizer effect can last 7 to 10 days. When spraying, the concentration used must be strictly controlled. Generally, urea is 0.1%, superphosphate is 0.5% to 1.0%, and potassium dihydrogen phosphate is 0.05% to 0.1%. When spraying, choose a clear, windless morning or evening and spray the fertilizer solution evenly on both the front and back sides of the plant leaves, with wetting as the appropriate degree.

Fertilizing time and precautions

Fertilizing potted flowers in spring should be done on a clear morning or evening. Fertilizing is not suitable on rainy days or when the potting soil is wet. Before fertilizing, it is best to loosen the potting soil first, and apply after the potting soil is slightly dry, which helps the fertilizer water seep down. After fertilizing, immediately spray the leaf surface with clean water to avoid fertilizer solution contaminating the leaf surface and causing yellow or scorched leaves. The next day, water once again to promote root absorption and use of the fertilizer.

For seedlings that have just emerged, newly rooted cuttings and newly repotted flowers, do not fertilize for the time being, otherwise it will affect their root development and may even lead to death.

Soil: Preparing potting mix

Commonly used materials for preparing potting mix

Commonly used materials include garden soil, leaf mold, peat soil, river sand, rice husk ash, sawdust and moss. Garden soil is the surface-layer matured soil from vegetable gardens and orchards and contains a certain amount of humus; leaf mold is formed by piling up leaves, straw and dry grass with soil and letting them rot. It has a high humus content, strong water retention and good permeability; peat soil is ancient plant material buried underground that has not completely rotted and decomposed. It is rich in organic matter and is acidic or neutral; river sand is coarse sand used in construction. Mixing in a certain proportion of river sand helps improve soil permeability and drainage; rice husk ash is the ash after rice husks are burned. It is rich in potassium fertilizer and is somewhat alkaline. Mixing it in can make the soil loose; sawdust, after fermentation and decomposition, mixed into the soil can change the soil's looseness and water absorption; moss, after being sun-dried and mixed into the soil, can make the soil loose with good drainage and air permeability.

Commonly used proportions for preparing potting mix

Different regions also have different natural resources. Each place should, according to the different requirements of different types of flowers for soil nutrient status, aeration status, drainage capacity and pH, use local materials to prepare a suitable potting mix. For example, in North China, leaf mold, garden soil and river sand can be used to prepare potting mix. For growing general herbaceous flowers, use 3 parts leaf mold, 5 parts garden soil and 2 parts river sand; for growing greenhouse flowers, use 4 parts leaf mold, 4 parts garden soil and 2 parts river sand; for growing woody flowers, use 4 parts leaf mold, 5 parts garden soil and 1 part river sand; for sowing and raising seedlings, use 5 parts leaf mold, 3 parts garden soil and 2 parts river sand to prepare the potting mix.

Measuring and adjusting the pH of potting mix

The simplest way to measure the pH of potting mix is to buy a box of pH test paper from a reagent store; the box contains a standard color chart. When measuring, take a small spoonful of potting mix and put it into a clean glass cup or small bowl, add distilled water or cooled boiled water at a soil-to-water ratio of 1:2, stir fully and evenly, and after it settles, put a strip of pH test paper into the aqueous solution for about 1 to 2 seconds. After taking it out, compare it with the standard color chart to judge whether the pH of the potting mix is high or low.

According to the measurement results, potting mix with unsuitable pH can be adjusted: if it is too acidic, add lime powder or plant ash to the potting mix to raise the pH value; if it is too alkaline, add sulfur powder to the potting mix to lower the pH value, thereby achieving the required pH.

Disinfection of potting mix

Potting mix often carries pathogens, bacteria, nematodes, insect eggs and weed seeds, so disinfection treatment is needed. Common disinfection methods include: (1) Sun exposure: in hot summer, spread the potting mix on a cement surface and expose it to the sun for 2 to 3 days, turning it 2 to 3 times in between. (2) Steam heating: pass steam at 100°C to 120°C into the potting mix for 40 to 60 minutes. (3) Stir-frying in an iron pot: put the potting mix into an iron pot and stir-fry over fire for 20 to 30 minutes, with the temperature reaching about 120°C, stirring constantly. (4) Chemical disinfection: for each cubic meter of potting mix, use 400 ml to 500 ml of 40% formalin solution (that is, formaldehyde), dilute with water 50 times, spray evenly on the potting mix, then pile the potting mix up, cover with plastic film, keep it sealed for 48 hours, then spread it out to air for 7 to 10 days before use.

Spring is here. Fertilize and change the soil well for the flowers and plants at home. New life begins again. Fengqiaoju Flower Network, your gardening expert by your side.