What fertilizers should I use for cucumbers in a greenhouse?

In recent years, summer weather has not always been favorable for growing cucumbers in garden beds. Therefore, an increasing number of vegetable growers are choosing to grow heat-loving cucumbers in protected ground structures. The yield of greenhouse cucumbers is typically 3-4 times higher than that of cucumbers grown in a garden bed.

Due to this, greenhouse cucumbers produce significantly more nutrients with their harvest than cucumbers grown outdoors.

Why do we need fertilizers?

Why should cucumbers in protected soil be fed during the growing season if the soil was well-fertilized with organic matter and mineral fertilizers during the primary digging?

The need for fertilizing arises because cucumbers have very weak roots, unable to absorb nutrients from the deep soil. The rapidly growing vegetative mass of cucumbers exhausts all the nutrients stored in the surface soil within the first month of life.

To produce a decent harvest of cucumbers, maintain a high level of plant immunity, and increase their resistance to dangerous diseases, it is necessary to apply mineral fertilizers and organic matter throughout the entire cucumber growing period.

Cucumbers require fairly high relative humidity and regular fertilizing to thrive. All fertilizing and watering should be done in the morning. This will allow the plants to dry before evening and prevent them from becoming susceptible to fungal diseases. In the absence of intense sunlight, there's no risk of leaf burn.

Immediately after placing the plants in their permanent location in the greenhouse, you should think about their first feeding. But this doesn't mean that cucumber seedlings don't need to be fed at all.

Feeding Timing. How Often to Feed

Fertilizing the soil intended for cucumbers should begin in the fall. During the fall tillage, add one bucket of compost or humus per square meter. Considering that the soil solution in greenhouses is typically more acidic than average, 500 grams of lime per square meter should be added simultaneously with the organic matter.

In the spring, the area where the cucumbers will grow is fertilized with mineral fertilizers 8 days before planting the seedlings. For each square meter, you need to apply:

• 30 g ammonium nitrate;
• 20 g potassium sulfate;
• 30 g superphosphate.

After this, the soil is dug up and then disinfected with a solution of potassium permanganate.

It has been established that to obtain a decent harvest of cucumbers in a greenhouse, after planting, they need to be fertilized at least 5 times:

• 1st feeding is carried out 13 days after planting the seedlings with fertilizers containing potassium and nitrogen;
• 2. Top dressing is carried out when plants enter the flowering phase, using fertilizers containing potassium, nitrogen, magnesium and microelements;
• 3. Top dressing is timed to coincide with the beginning of fruiting and is carried out using the same means as the second time;
• 4. Top dressing is carried out 15-18 days after the third and phosphorus-containing fertilizers are added to the usual composition;
• After another 17 days, the 5th feeding with complex mineral fertilizers is planned.

Feeding seedlings

A fertilizing cycle should begin when growing cucumber seedlings. Fertilizers are applied when preparing the nutrient-rich soil for the seedlings. This soil should consist of:

• humus (40% by volume);
• turf soil (50%);
• sand or sawdust to make the soil looser (10%).

Additionally, add a small amount of wood ash to the mixture, and then water it with a hot solution of potassium permanganate. Wood ash is a source of potassium, and potassium permanganate is a source of manganese. These nutrients are essential for the normal growth and development of cucumbers.

Cucumber seedlings are first fed when they have 1-2 true leaves. At this stage, nitrogen, potassium, and phosphorus fertilizers should be applied to accelerate stem and leaf growth and promote the development of a strong root system.

After two weeks, the seedlings in the nursery are fed again with the same fertilizer mixture. Having received another dose of nutrients, the seedlings gain even greater immunity and are better able to withstand the stress of subsequent transplantation into the ground in their permanent location.

Fertilizing after planting

No matter how carefully we transplant seedlings to a new location, we can't completely avoid plant stress. Therefore, approximately 10-14 days after transplanting the seedlings to their new location, it's necessary to fertilize them to reduce stress and stimulate vegetative growth, as well as to promote the development of a well-developed root system.

There are many feeding recipes, but you can settle on this one:

• dissolve 20 g of superphosphate in 10 liters of water;
• stir well until the fertilizer is completely dissolved;
• add 20 g of potassium sulfate and 15 g of ammonium nitrate;
• Mix the mixture thoroughly again.

Water the cucumbers with the resulting solution. It should be enough for 12-15 plants.

Vegetable growers use fertilizers that do not contain nitrogen in nitrate form, such as:

• potassium sulfate;
• crystallin A;
• humate fertilizer.

Mullein is considered an excellent fertilizer. When applied between cucumber rows, it not only provides a variety of nutrients but also, as it decomposes, releases carbon dioxide, essential for normal photosynthesis.

During flowering

The next fertilization of cucumber crops should be performed during the mass flowering phase. This usually occurs 16-22 days after the first fertilization of seedlings transplanted to a new location. During this period, cucumbers are still growing and developing rapidly, so they require nitrogen. However, along with nitrogen, the formation of flowers and ovaries requires more potassium, and micronutrients such as magnesium and boron.

Bird droppings and mullein have proven effective for this type of fertilizer. If you plan to feed cucumbers with bird droppings, you should take the following preparatory steps:

• dilute chicken manure with water in a ratio of 1:15;
• take 10 liters of this solution and add 150 g of wood ash to it;
• Mix the mixture thoroughly.

Water the cucumber beds with the resulting solution at the rate of 1 liter of liquid per 1 plant.

If you're planning to use mullein to feed flowering cucumbers, you can prepare a working solution using this recipe:

• pour 10 liters of water into a bucket;
• add 500 ml of liquid mullein and 1 tbsp of nitrophoska to it;
• mix the mixture and add another 150 g of ash, 0.5 g of boric acid and 0.3 g of manganese sulfate;
• Mix the solution thoroughly.

Water the soil under the cucumbers with the prepared solution, pouring 3 liters per square meter.

During fruiting

This is one of the most important stages in cucumber cultivation. Forming cucumbers require more potassium fertilizer, so it should be applied promptly. For additional feeding, you can use the same fertilizer formulas as for flowering cucumbers, or you can try new combinations:

• dissolve 30 g of potassium nitrate in a bucket of water;
• add 50 g of urea there;
• wood ash in the amount of 500 g;
• Mix the composition well.

Apply top dressing at the root at a rate of 8 liters per m2.

Root and foliar feeding

During the growing season, cucumbers grown in greenhouses require regular fertilizing. Depending on the method of application, fertilizing can be divided into:

• root;
• extraroot.

Root feeding

Such fertilization can be accomplished by applying mineral and organic fertilizers, or a combination of both. In principle, it's possible to apply only root fertilizers, without spraying the plants with fertilizer. However, it's best to combine both methods.

Root feeding should be done after pre-moistening the soil. Plants benefit from fertilizing on a cloudy day.

Seedlings are transplanted to their permanent location in the greenhouse when they have four true leaves. They require nitrogen, potassium, and phosphorus for growth and development. These elements are often insufficient in the soil, and sometimes unavailable. Therefore, young cucumber plants need to be fertilized.

For fertilizing, you can use a ready-made mineral fertilizer complex containing all the necessary nutrients in a balanced form. You can also prepare your own working solution of mineral fertilizers containing these three essential nutrients.

Fertilizer recipe:

• take 10 liters of water;
• dissolve 20 g of superphosphate, 15 g of ammonium nitrate and 15 g of potassium sulfate in water;
• Stir the mixture until the ingredients are completely dissolved.

This prepared solution should be enough to feed 15 young plants.

Cucumbers can get well-balanced nutrition from azophoska or nitroammophoska. They contain the full range of macronutrients needed by young cucumbers. A solution is prepared by diluting 1 tablespoon of the substance in 10 liters of water.

It is common knowledge that as greenhouse cucumbers grow and develop, their need for certain types of fertilizers changes, and their overall need for nutrients increases.

Foliar feeding

Greenhouse cucumbers can also be fed foliarly using ready-made mineral fertilizer complexes or homemade mineral fertilizer mixtures. The same types of fertilizers used for root feeding are suitable. The only difference is the concentration of the nutrient solution. When applying foliar fertilizer, reduce the concentration by half to avoid burning the plants.

Three recipes for foliar feeding:

• dissolve 10 g of superphosphate, 30 g of potassium nitrate, 1 g of boric acid, 0.4 g of manganese sulfate, 0.1 g of zinc sulfate in a bucket of water;
• 50 g of urea per 10 l of water;
• Dissolve 1 teaspoon of boric acid and 10 crystals of potassium permanganate in 1 liter of water.

Use the prepared solutions for foliar feeding until the leaves are completely wet.

Foliar feeding is more effective than root feeding and should be preferred when cucumbers are grown in relatively cold soil. Plants are known to absorb nutrients less effectively in cold soil.

Foliar application is carried out using a sprayer, ensuring a very fine mist of liquid. The smaller the droplet size, the more efficiently the plant absorbs the water and its dissolved nutrients.

Mineral fertilizers

Many gardeners use mineral fertilizers for fertilizing.

The following composition has proven to be effective in practice:

• place 20 g of superphosphate, 10 g of potassium chloride and 10 g of ammonium nitrate in a bucket;
• mix the mixture.

The prepared solution is used to moisten the root zone of cucumbers and should be enough for 10 plants.

To perform the first feeding of cucumbers, after planting them in a permanent location in a greenhouse, you can use the following fertilizer recipes:

• dissolve 1 tablespoon of urea and 60 g of superphosphate in a bucket of water;
• Sprinkle 5 g of ammophos over the surface and incorporate it into the soil by loosening;
• Take 10 g of ammonium nitrate, superphosphate, potassium salt and dissolve them in 10 liters of water.

The following recipes are suitable for the second and third cucumber feeding:

• 20 g of potassium nitrate, 30 g of ammonium nitrate, 40 g of superphosphate per 10 liters of water;
• Dissolve 20 g of potassium nitrate in 10 liters of water.

During the fruiting phase of cucumbers, the following doses of fertilizer per bucket of water are recommended:

• ammonium nitrate – 15-20 g;
• superphosphate – 20 g;
• potassium sulfate – 20 g.

Organic fertilizers

Not all gardeners prefer to feed their cucumbers with mineral fertilizers. Some are staunch supporters of organic fertilizers and folk remedies.

A popular way to fertilize cucumbers is by using a weed infusion. It's prized for its easily digestible nitrogen content. To prepare it, follow these steps:

• place chopped weeds in a bucket;
• fill with water;
• let the mixture sit for 4 days until bubbles and a sour smell appear;
• dilute the mother liquor with water in a ratio of 1:5.

Water the cucumbers at the roots with the prepared working solution, pouring 5 liters per square meter. It is advisable to moisten the soil before fertilizing.

When the first cucumber ovaries appear, an organic fertilizer based on mullein and chicken manure is often used, prepared according to the following recipe:

• place 1 liter of liquid mullein and 0.5 kg of bird droppings in a bucket;
• fill the ingredients with water to the top;
• mix.

Water the cucumbers at the roots with the prepared solution, at a rate of 1 liter per 1 plant.

For the first feeding of cucumbers, ash solution can also be used. The recipe is as follows:

• pour 150 g of wood ash into a bucket of water;
• mix the mixture.

Use the solution for root feeding, pouring 1 liter of liquid under each root.

Here is another popular recipe for preparing fertilizer for cucumbers:

• dilute 500 ml of mullein in a bucket of water and add 1 tbsp of nitrophoska;
• mix the mixture thoroughly;
• add another 50 g of potassium sulfate, 0.5 g of boric acid and 0.3 g of manganese sulfate;
• Stir the mixture until all ingredients are completely dissolved.

Water the cucumbers at the roots with the prepared solution, applying 3 liters per square meter. The greatest effect from this feeding is observed during flowering and fruiting.

What to do if you applied too much fertilizer

It's better to slightly underfeed cucumbers in the garden than overfeed them. The latter can cause undesirable effects, such as leaf discoloration, stunted growth, sprouting shoots, or leaf burn. Here's what cucumbers overfed with a particular fertilizer will look like:

1. If cucumber plants are overfed with nitrogen, ovary formation is delayed. The vines become excessively thick, and the leaves become denser and darker green.
2. Excessive phosphorus fertilizers can cause yellowing of the leaves, which can develop necrotic spots that grow larger. If appropriate measures are not taken, the leaves will begin to fall off.
3. If too much calcium has been added to the soil, this can also be seen in the leaves. They develop interveinal chlorosis.
4. Cucumber plants overfed with potassium immediately begin to slow down their growth.

If an error does occur and you've overdosed on fertilizer, this will inevitably affect the plants. A thorough watering of 15 liters per square meter can normalize the situation. This technique flushes excess fertilizer from the upper soil layers into deeper layers inaccessible to cucumber roots. Flushing the soil when there's excess fertilizer in the soil always produces positive results.

How to understand that there is not enough fertilizer

Nutrient deficiencies always affect the appearance of plants, their leaves, and fruits. Experienced gardeners can easily visually identify nutrient deficiencies in cucumbers.

The problem is initially indicated by discoloration of the leaf blades. If this is missed and the deficiency is not corrected, it will be impossible to produce attractive, marketable fruit. Later, leaves often become deformed and smaller, stems thin, shoot growth stops, and fruit becomes distorted. Deficiencies of each essential nutrient have specific symptoms.

In addition to essential nutrients, cucumbers may lack micronutrients, as well as oxygen and moisture in the soil. If nutrition is insufficient, cucumbers become susceptible to fungal diseases, grow slowly, and their fruits lose flavor. The sooner the problem is identified and appropriate measures taken, the better for the cucumber harvest and its quality.

What to feed them so they don't turn yellow?

Sometimes, even with fertilizer, gardeners encounter a yellowing of cucumber leaves. This can occur in a greenhouse with a normal microclimate and in the absence of pests and diseases, which can also cause yellowing of the leaves.

If you notice that your cucumber plants are starting to turn yellow, try using the following foliar feeding:

• Place a loaf of bread in a ten-liter bucket overnight;
• In the morning, knead the bread and add a bottle of iodine to the bucket;
• dilute 1 liter of the resulting mother liquor in 10 liters of water.

After straining, apply the solution to the leaves for spraying.

In addition, gardeners make a nutrient solution for foliar feeding from nettles according to the following recipe:

• prepare young nettles free of seeds;
• place it in a bucket and fill it with water;
• The mixture must be left to infuse for 22 hours.

To prepare a working solution, dilute 1 liter of the stock solution in 10 liters of water and begin spraying.

What to feed if they turn pale?

Pale cucumber leaves in a greenhouse are usually caused by a nitrogen or iron deficiency in the soil, as well as by pathogenic microorganisms. To solve this problem, simply use one of the following remedies:

1. Dissolve 1 liter of liquid mullein in a bucket of water. Let it sit for a while, then stir. Water the cucumbers with this solution at the roots, at a rate of 1 liter per plant.
2. Collect weeds from the garden and chop them up. Place them in a bucket and add water. Let the mixture sit for 14 hours. Before use, dilute the solution with water at a ratio of 1:5 and begin spraying.
3. Place two tablespoons of urea in a bucket of water and stir until the fertilizer is completely dissolved. Spray the plants' leaves with the prepared working solution.

What fertilizers should I add to make them plump?

When fertilizing cucumber plants, gardeners rely on folk remedies that are always at hand. With these remedies, they quickly restore the plants' healthy appearance and encourage them to produce abundant fruit.

More often than usual, to make cucumber dressings thicker, the following is used:

• ash left over from burning wood;
• nitroammophoska;
• onion peel infusion;
• chicken manure;
• yeast;
• ready-made fertilizer complexes containing a full range of essential nutrients.

Top dressing with nitroammophoska

As is known, nitroammophoska contains three essential nutrients in the ratio required for plants: nitrogen, potassium and phosphorus.

It has been observed that after applying nitroammophoska to cucumbers, the number of ovaries and the duration of fruiting increase. There are two methods for feeding cucumbers with nitroammophoska:

• incorporating the chemical into the soil before planting cucumber seedlings;
• watering at the roots until the ovaries appear.

Before planting cucumbers in their permanent location, apply 30 g of nitroammophoska per square meter of plot. To promote abundant fruit set, prepare a working solution consisting of 1 tablespoon of fertilizer and 5 liters of water. The recommended application rate is 500 ml per plant.

Ash top dressing

To perform this feeding, you must first prepare a working solution, as follows:

• place 250 g of ash in a bucket;
• fill it with warm water;
• mix the mixture.

Water the plants with the resulting liquid solution, pouring 1 liter under each bush.

Yeast

The following macro- and microelements have been found in yeast: nitrogen, potassium, phosphorus, iron, manganese, and others. To prepare a working solution, follow these steps:

• take a bucket of water;
• dissolve a packet of yeast in it;
• leave to infuse for 22 hours.

Water the cucumbers with a liquid solution, pouring 1 liter under each root.

Chicken manure

Fresh and rotted bird droppings are used for fertilizing. Dilute rotted droppings with water at a ratio of 1:10 and pour 0.7-0.8 liters of the solution under each plant. To use fresh chicken droppings, dilute them with water at a ratio of 1:20 and water the spaces between the cucumber rows. Remember to thoroughly moisten the beds before fertilizing to avoid burning the roots.

Onion peel

Onion peels are a waste product, but it turns out they can be used as fertilizer for cucumbers. Here's the recipe:

• put 200 g of onion peel into a bucket of water;
• pour water over the husk;
• place the bucket on the gas and heat until boiling;
• let the mixture cool to room temperature.

Water the cucumbers with this solution at the rate of 1 liter per bush.

How to determine by appearance what fertilizers are lacking

Using so-called foliar diagnostics, you can determine which nutrients greenhouse cucumbers are lacking based on the color and shape of the leaves. If the cucumbers appear healthy, there's no need to rush into fertilizing.

But when you notice leaves suddenly changing color or shape, cucumber vines slowing down, or the plant stopping flowering, you need to urgently identify the cause of these undesirable phenomena and promptly apply the necessary fertilizers. Here's how a deficiency of essential nutrients in cucumber plants manifests itself in practice, and what you can do to solve the problem:

1. Nitrogen deficiencyWhen experiencing nitrogen deficiency, plants stop growing young shoots, and the leaves become smaller and paler. Later, the leaf blades turn yellow and dry out. Flowering of cucumber plants becomes sparse, ovaries become fewer, and cucumbers grow poorly. A quick solution to this problem is to apply a root dressing of liquid manure or ammonium nitrate. Apply 1 kg of liquid manure and 30 g of ammonium nitrate per 1 m² of plot area. Foliar feeding with urea is also acceptable, dissolving 30 g of the preparation in 10 liters of water.
2. Phosphorus deficiencyIts symptoms first appear on older leaves, which take on a blue or red tint. Deficiency of this element is most often observed in acidic soils. To correct a phosphorus deficiency, follow these steps:

• take a bucket of water;
• place 50 g of superphosphate there;
• mix thoroughly until the granules are completely dissolved;
• filter the solution.

Spray the cucumber plants with the prepared solution. After 15 days, repeat the feeding with mineral complex fertilizer at a rate of 1 tablespoon per 10 liters of water.

1. Potassium deficiencyWhen cucumbers experience a potassium deficiency, rusty spots appear on their leaves, most often along the edges of the leaf blades. The leaves themselves become corrugated. Cucumber shoots become thin and barely grow. To solve this problem, cucumber plants are fed with ash or a potassium chloride solution.
2. Magnesium deficiencyThis element is essential for chlorophyll molecules, and without it, photosynthesis is impossible. Magnesium deficiency slows the transport of photosynthetic products to various parts of the plant. This slows cucumber growth, roots stop developing, and cannot adequately absorb water and the nutrients dissolved in it. Leaves wrinkle and develop yellow spots. Only the veins remain green. This problem can be solved by applying magnesium sulfate or magnesium nitrate.
3. Sulfur deficiencyIt causes a general slowdown in plant growth. Stems do not thicken and remain thin and brittle. Leaves become whitish, and their veins become pale. If a deficiency of this element is detected, cucumbers should be fed with calcium sulfate or magnesium sulfate.
4. Calcium deficiencyThis causes the leaves to become deformed, curling, and wilting. Plant immunity is weakened, and they can become susceptible to rot. Roots, fruits, and stems rot. A deficiency of this element causes dry, brownish margins to appear on leaf tips. Timely application of calcium nitrate, at the first signs of this problem, resolves this issue.

What microelements does a plant need?

Cucumber nutrition must include a full range of essential macro- and micronutrients. Macronutrients include nitrogen, phosphorus, sulfur, magnesium, calcium, and potassium, so named because they are required by plants in relatively large quantities.

Along with these elements, there are a number of others that are also very important for nutrition but are absorbed by plants in small quantities. These are called micronutrients. Deficient micronutrient levels can be replenished by applying organic and complex fertilizers.

When planning fertilizing, consider the overall condition of the plants. Deficiencies of individual elements can be determined visually by the color of the leaves, the shape of the inflorescences, and the shape of the fruits.

Typically, a deficiency of a particular element becomes apparent through external changes. Knowing these signs can help determine what your cucumber plants are lacking. Signs that indicate a deficiency of a particular micronutrient include:

1. Copper deficiencyFlower petals fall prematurely. Cucumber shoots weaken and wither. Leaves turn pale.
2. Boron deficiencyInflorescence drop. Fruit shape distortion. Yellow streaks appear on leaf blades and fruits.
3. Manganese deficiencyThis element is responsible for chlorophyll production and oxidation processes. Manganese deficiency causes dark green spots to appear on leaves, and the leaf blades themselves lose their original color.
4. Iron deficiencyIn this variant, young leaves lose their ability to photosynthesize. The upper leaves of the plants begin to turn yellow, and the remaining leaf blades lighten in color, starting from the veins.
5. Zinc deficiencyThis causes individual sections of the leaves to die off. Lead-colored or brown spots appear on the leaf blades, the tissue dies, and the veins turn black.

Each vegetable grower must decide for themselves which fertilizing method to use. They can use only mineral fertilizers or opt for organic fertilizers. A combination of both is probably best. The key is to apply fertilizer when needed and never exceed the recommended nutrient solution concentration. If you follow these recommendations, your cucumber plants are sure to reward you with a bountiful harvest of delicious cucumbers.