7 Tips on How to Grow Strong & Healthy Seedlings

7 Tips on How to Grow Strong & Healthy Seedlings
7 Tips on How to Grow Strong & Healthy Seedlings

Successful cultivation of healthy seedlings requires correct agricultural techniques. If the work is carried out qualitatively and meets the requirements of sowing technology and care, then seedling raising is not a difficult process, and the planting material is planted in an absolutely healthy and permanent place. However, there are cases when healthy, friendly seedlings begin to wilt, and after 1-3 days, the seedlings die completely.

The cause may be non-infectious plant damage related to violation of agronomic requirements of cultivation conditions (insufficient light, low temperature, high humidity, over-fertilization, etc.), so that weak seedlings affected by soil infection in the form of fungal and bacterial diseases blackleg, rot and other forms. This article is devoted to how to avoid seedling diseases caused by cultivation errors and how to overcome blackleg and other infections.


Most of the agrotechnical measures are preventive, but if these simple measures are not followed, it won’t be easy to raise healthy seedlings.

Sterilize seedling soil mixtures

Disinfection of soil and soil mixture should be carried out as a mandatory agronomic measure when raising seedlings in containers, pots, boxes, and other vessels.

If you do not have time to sterilize the soil mixture in advance, you can do so before planting using one of the recommended methods or your own original method.

Pour the prepared soil into boiling water and dissolve manganese (1-2% solution) in the water. Stir and dry the spilled soil for 2-3 days. Repeat the procedure after 3 days with a solution of soda water.
Dissolve 100 g of baking soda per 2.5 Gal (10 liters) of water. At each reception, the soil is dried and agitated.
2 weeks before sowing, treat the soil mixture with a biological agent according to the recommendations: Universal Organic Biofungicide.
The soil can be treated with a Bordeaux mixture (1% solution) or copper sulfate (0.5% solution) before sowing. The concentration of the solution should be low so as not to burn the young roots during germination.
After all disinfection procedures, dry the soil mixture, fill the container with warm water heated to 75°F (24°C), and sow the seeds in moist soil.

Be found. Seedlings grown in peat pots and plastic boxes were virtually free of blackleg disease.

Maintaining a neutral soil environment

Acidic soil conditions are favorable for the development of soil fungal infections. Therefore, it is necessary to test the acidity of the soil (with litmus paper) before sowing. The best is considered to be pH = 6.0-6.5. Lime, dolomite powder, and wood ash are used to neutralize the soil.

A neutral environment is very important for seedlings. As soil acidity increases, some nutrients become unavailable to the plants. Some gardeners treat the soil under seedlings with dry ash and add sand to maintain a neutral response of the soil while drying it out with excess moisture.

Maintaining the density of seedlings and sprouts

In large greenhouses, it is necessary to sow seeds at the recommended rate and not to overestimate the density of plants. Seedlings that are too dense can be broken up by pulling out weaker plants: do not pull out, but pull out weaker shoots at the soil level.

Thickened seedlings create their own moist microclimate and provoke the growth of disease-causing fungi. When cutting seedlings, leave a distance of 0.6-0.8inch (1.5-2 cm) between seedlings, which will ensure good ventilation and sufficient light for each seedling. When sowing seedlings into individual containers, it is best to sow 2 seeds per plant, and after germination, pull out the weak plants (you can also pull them up).

Observe the air and soil temperature regime

As a rule, crops grown through seedlings are heat-loving. Therefore, the necessary levels of air and soil temperatures need to be strictly maintained. Seed germination begins with air temperatures within 60-64°F (16-18°C), but the most aggressive sprouts emerge when air temperatures rise to 77-86°F (25-30°C), depending on the culture.

Immediately after mass germination, the air temperature must drop to 60-64°F (16-18°C) so that seedlings do not elongate. In this mode, seedlings rapidly form root systems. Therefore, the optimum regime for seedlings of most vegetable crops is 68-77°F (20-25°C) during the day and 60-64°F (16-18°C) at night.

Soil temperature is no less important for seedlings. Too much cold, as well as too much heat, can lead to the suppression of seedlings. The optimum condition is 64-71°F (18-22°C). It is especially important to maintain this soil temperature regime during the harvesting process. A drop in temperature below 60 °F (16 °C) will result in deterioration of nutrient and water reception by the plant and reduced energy for seedling roots.

Irrigation regime and air humidity observations

The soil under the seedlings should be kept moderately moist. Sprouts should be watered in the morning with water heated to 68°F (20°C) no more than 1-2 times per week, but better after the soil surface has dried. Water the seedlings along the edges of the container when growing at home or along the furrow in the greenhouse.

Water the seedlings during the first 6-10 days so that the water does not get on the plants. Frequent and heavy watering can deteriorate the air regime of the soil and the activity of the root system. In addition, high humidity of soil and air promotes the rapid development of fungal diseases, and seedlings may die. Therefore, after watering, strongly moistened soil should be dried with dry sand (which is better) or watered through trays instead.

You can use finely ground topsoil peat or dry humus to cover the watered soil. The optimum humidity level in the room should be kept at 70-75%. Ventilate the room to reduce humidity, but do not air it out.

Without extra light, you cannot get quality seedlings

If the conditions at home allow it and you do not need many seedlings, then place the container on a windowsill where the daylight shines. Sometimes, however, additional lighting is needed regardless of the number of seedlings planted, especially when sowing seeds in January-February.

For seedlings, a minimum of 12-14 hours of light per day is recommended, but in early spring and winter, plants receive up to 50% of the required light. At low light intensities, plants will shrivel, elongate and bend toward the light source. Therefore, lights are installed in family rooms and greenhouses to provide seedlings with the necessary level and intensity of light, but not with hot lights, but special – cold light.

Usually, the heavy light nursery is carried out from 7 a.m. to 8 p.m. Many gardeners use daylight from plant lights or fluorescent lamps. Now, most greenhouse gardeners are switching to LED lights. They emit a red and blue spectrum that improves seedling development, give off little heat, and are very energy efficient.

Don’t over-fertilize seedlings

Buy ready-made soil mixes for home seedlings that do not require additional fertilizers, especially nitrogen. If the soil mixture is self-cooking, the plants will have to be fertilized. Although with a properly prepared soil mixture, you can do without fertilizer, especially since crops, seedlings have a very short germination period (27-35 days).

Normally growing plants have green leaves and strong stems that do not need nutrients. Excessive nitrogen nutrition is very painful for young seedlings. It causes the elongation of plants and their accommodation. Stems become thin and light, internodes elongate, and leaves – a painful dark green shade. The general weakening of the plants helps to accelerate the infection of the crop. To avoid over-fertilization, it is not necessary to fertilize seedlings before harvesting.

Within 7-15 days after picking, foliar application of “nitro phosphate and potassium-based high-efficiency complex fertilizer,” ash infusion, and the addition of growth promoters and others. If the nitrogen content of seedlings is too high, you can spend a lot of water and immediately drain the trays of water and cover the soil with dry sand in layers not exceeding 0.8inch (2 cm). Small sawdust or grain bran, or finely chopped straw can be placed on the soil surface. Soil microorganisms will begin to break down the fiber and use the excess nitrogen in the soil for this purpose.

To improve the nutrient balance during this period, you can spray the plants with Solgar (Chelated Iron).

Successful cultivation of healthy seedlings requires correct agricultural techniques
Successful cultivation of healthy seedlings requires correct agricultural techniques


Agrochemical measures are the quickest and most reliable way to protect seedlings from diseases. Among these diseases, fungal and bacterial infections are the most pernicious ones. Particularly dangerous for young seedlings is blackleg.

The degree of damage from this disease is very high – up to epizootic. Within 2-3 days, the plant roots are affected by the growing fungus, and the seedlings die. That is why it is so important to observe all agrotechnical requirements of seedlings.

What contributes to the development of black legs on seedlings?

Despite all preparations for planting seedlings, some typical soil fungal spores, called sclerotia, remain alive and dormant. They accumulate on soil, plant residues, seeds, and wooden greenhouse props. The accumulated infection, under the right conditions, begins to multiply vigorously. The fungus proliferates in the soil.

Plants are infected at the roots, and the infection manifests itself as wilting and lodging of seedlings. The spots of individual diseased plants merge into one continuous field within a short period of time. If seedlings are not treated immediately, they will die completely. In order to protect the plants adequately, agricultural techniques and agrochemical works should be carried out simultaneously.

Distinctive features of blackleg disease

If all agrotechnical requirements are complied with, but seedlings are lodged in separate, rapidly increasing centers, this means that the seedlings or already young ones are already sick. In the case of black stem disease, the stem turns black at the roots, and a black cross can be clearly seen. The disease is caused by several types of soil fungi: some fungi affect the seedlings during the first days of their development.

Diseased seedlings during this period turn black, harden, and rot in the areas where the fungus sprouts inside the plant (roots, root neck, lower part of the seedling).

Other categories of fungi affect mature seedlings ready for planting. It manifests itself as thinning and darkening (to black) of the root neck and drying of the lesioned part. The plants do not die, but planted in the ground for a long time, they become sick and formless healthy products (especially crops with affected cabbage heads).

What should I do if my seedlings get the blackleg disease?

The first days of germination are usually not watered to avoid provoking lodging. If the development of the disease cannot be prevented, the diseased plant should be removed and burned. The part of the soil where the diseased plant is located should also be removed, and the area should be treated with an ash soak.

Usually, such a solution is prepared in advance so that no valuable time is lost. Dissolve 2 cups of wood ash in 0.25-0.5 Gal (1-2 liters) of boiling water. Influence for 6-7 hours. Filter and dilute in 2.3-2.5 Gal (9-10 liters) of warm water. Spray plants and soil with this solution, approximately 0.25 Gal/11 sq. ft. At home, you will need to arrange the tray with the seedlings in one place before spraying.

After 5-7 days after 100% germination, treat with a fine dispersion spray with a solution of humic acid, which can significantly improve the plant’s immunity while having a negative effect on pests. The solution is prepared at the rate of 1 capful per 2.5 Gal (10 l) of warm water. Other immune preparations can also be used.

Today, experts offer a huge list of chemical and biochemical agents that help protect seedlings from various diseases, including blackleg disease. With independently cultured seedlings, the use of biological agents is much safer for the family’s health. They effectively kill soil fungi and fungal diseases on plants and are absolutely harmless to humans and pets.

Biological fungicides prepared according to the instructions can be systematically sprayed on plants and soil during the entire period of seedling cultivation, which will fully protect them not only from blackleg but also from rots, powdery mildew, phylloxera, pearl fungus, and other diseases. According to the recommendations for spraying and application to the soil – Trichodermin, etc.

An effective way to combat blackleg is loosening and starting the soil. Loosening of the crust will increase the access of oxygen to the roots and eliminate the process of decay. Within 2-3 days of mass germination, gently soak and water the sprouts using troughs and trenches. Seedlings should be kept dry during this period.

Before picking the plants, as a precaution, treat the soil mixture with colloidal sulfur at a rate of 5 grams per 11 square feet. Kemira fertilizer can be added to the soil mixture in very small doses and mixed thoroughly. The available form and availability of micronutrients in the fertilizer will help the plants adapt to their new environment more quickly after harvesting.

Some gardeners add preparations of “fungal biological preparations for the prevention and treatment of plants” to the soil mixture and mix it well before picking the seedlings to prevent blackleg disease. Plants treated with this soil treatment do not actually get the blackleg disease.

Copper-containing preparations inhibit not only fungal but also viral infections. Therefore, it is recommended to apply them to protect mature seedlings from blackleg disease before planting in permanent locations. Before planting, the above-mentioned preparations are introduced into the well as a solution of phytosporin, Trichodermin. If not prepared, then each hole was watered with a 1% solution of manganese the day before transplanting, before planting the seedlings.

Thus, observing all the requirements of agricultural engineering for seedling cultivation, it is possible to obtain healthy planting material.

Would you please share tips and proven methods for healthy seedlings in the comments of this article?

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