Growing flower seedlings in a greenhouse is a real art of balance. Although it provides ideal conditions, if attention is not paid to the details, these advantages can become detrimental to the plants.

Here are the key things you need to pay attention to so that your seedlings are healthy, strong and ready for transplanting:

1. Temperature is the heart of the greenhouse

Flower seedlings are particularly sensitive to temperature fluctuations.

Optimal range: Most flowers like daytime temperatures between 18 and 22 °C, while night temperatures should not fall below 12-15 °C.

Overheating: The sun can raise the temperature in the greenhouse above 30°C in a very short time, which can seriously damage young plants. Be sure to use a thermometer, preferably one that records the minimum and maximum temperature.

2. Ventilating the greenhouse

Moisture without airflow is a recipe for disaster.

Air exchange: As soon as the temperature exceeds 20 °C, open the door or side vents. Fresh air brings CO2 needed for photosynthesis.

Disease prevention: Good ventilation dries out excess moisture on the leaves, which is essential to prevent “seedling blight” (a fungal disease that can destroy all seedlings in one night).

3. Light so that the seedlings do not “elongate”

One of the biggest problems is the lack of light, which makes the plants thin, pale and tall.

Cleanliness of foil or glass: Dust and dirt on the greenhouse can reduce light penetration by up to 30%. That is why it is important to wash the film regularly.

Spacing: As the plants grow, space the containers. If the leaves are touching, the plant will struggle for light and will start to grow taller instead of wider.

4. Watering and humidity of the substrate

Golden rule: Better a little less than too much.

Time: Water only in the morning. Plants should enter the night with dry leaves.

Water temperature: Never use ice water directly from a well or water supply. Allow the water in the greenhouse to reach room temperature so as not to shock the roots.

Drainage: Make sure pots or containers have good openings to drain excess water.

5. Nutrition

Seedlings grow in a small volume of soil and use up nutrients quickly.

First feeding: Usually begins when the plant develops its first pair of “true” leaves, not cotyledons.

Balance: In the beginning, use water-soluble fertilizers with an emphasis on phosphorus (P) for root development, and later balanced NPK fertilizers, writes Agroklub.

6. Tempering or preparation for the outside world

Plants that grew in the “luxury” of a greenhouse will experience a shock if you immediately take them outside.

Gradual adaptation: Ten days before selling or planting, increase aeration during the night and gradually reduce watering. It “steels” the tissue of the plant.