Growing in the Greenhouse: How Plants Thrive

Last updated on October 23rd, 2023 at 08:24 pm

Growing in the Greenhouse: How Plants Thrive

At the end of winter it is still uncomfortably cold outside. But even in the unheated greenhouse the temperatures sometimes rise so high that the first radishes and lettuces germinate towards the end of February. This makes growing in the greenhouse a lot of fun.
Growing in the greenhouse: using the right sowing soil

When growing in a greenhouse, you should always use a low-nutrient substrate. In ordinary potting soil, new roots would hardly form, as there are plenty of nutrients available. Only when the young seedlings have to go in search of food will they stretch their fine little roots throughout the entire sowing container and branch out well. Peat-free sowing soil is also available, for example from Floragard.

Spraying instead of watering

Growing in the Greenhouse: How Plants Thrive

Do not water the fine seeds of petunia, basil or busy lily with a watering can and keep them moist. Hand sprayers that produce a fine mist are better. This not only moistens the substrate evenly, but also provides the drought-sensitive seedlings with adequate humidity.
Another plus: seeds or fine seedlings are not washed out of the soil and there is no waterlogging.
Making the most of light

On dull spring days, at least the greenhouse cover must be clear. Only then will a large part of the scarce light reach the sun-hungry seedlings. In addition, the sun heats up the greenhouse much better that way. So get rid of algae, dust and co!
Sowing from February

Early vegetables for the greenhouse, cold frame and open field can be sown as early as February – either at the window or in the greenhouse, where it is much brighter but usually also cooler. Lamb’s lettuce, spinach, broad beans and radishes will not mind much. If, on the other hand, you want to pre-cultivate summer flowers or a fruit vegetable that requires warmth and takes a long time to grow, you can heat the greenhouse with a gas or electric heater. A special paraffin stove is more suitable for smaller houses.

See also  Are There Any Hardy Basil Varieties?

In general, however, the timing of the sowing date should be right. Outdoor cucumbers, for example, should not be planted until after the Ice Saints (mid-May). To prevent the young plants from growing too large, you should wait until mid-April before sowing.

Ensure a good seal

The best heating is of no use if greenhouse walls or door seals do not keep tight. However, many a small leak remains undetected. Here, cold air flows continuously into the greenhouse. A down, held close to the greenhouse shell, detects every crack. It is imperative to seal it before the young plants are planted. Bubble wrap without gaps reduces heat loss through leaks and also increases the insulating effect of the greenhouse cover.

Growing in the greenhouse: germination temperatures, sowing times and germination duration

Andean berry 22-24 °C, Feb./March, 7-14 days

Artichoke 18-25 °C, Feb./March, 15-25 days

Aubergine 22-24 °C, Feb./March, 6-14 days

Cauliflower 15-20 °C, Feb.-May, 5-10 days

Early and forcing kohlrabi 12-20 °C, Feb./March, 5-10 days

Early head cabbage 15-20 °C, Jan-May, 5-10 days

Peppers 22-24 °C, Feb-March, 5-20 days

Radish (direct sowing) 12-20 °C, end of Jan-April, 3-10 days

Lettuce (forcing and early varieties) 8-16 °C, February, 6-12 days

Lettuce (outdoor varieties) 8-16 °C, March-May, 6-12 days
Summer flowers

Fleissige Lieschen 18-23 °C, Feb./March, 15-30 days

Bateleur flower 12-20 °C, Feb.-May, 10-18 days

Liverwort (Ageratum) 22-26 °C, Feb./March, 10-15 days

Snapdragon (Antirrhinum) 16-20 °C, Feb./March, 15-25 days

Elf’s mirror (Nemesia) 18-22 °C, Feb.-June, 10-15 days

Lobelia 18-25 °C, Feb./March, 5-15 days

Petunia 18-23 °C, Feb./March, 10-15 days

See also  How To Harvest Sage Properly

Midday gold (Gazania) 18-23 °C, Feb-Apr, 10-20 days

Spider flower (Cleome) 18-24 °C, Feb./March, 15-25 days

Verbena 18-24 °C, Feb./March, 15-30


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

Leave a Reply

Your email address will not be published. Required fields are marked *