These days, garden centers offer a good range of young plants in the spring, but many excellent selections never appear on this list. This is why the most curious and demanding gardeners do their own seedlings year after year. When you grow good quantities of these plants, sowing your own seeds also turns out to be more economical, once the equipment costs have been amortized. And then, we always get a lot of pleasure and pride from seeing the young seedlings develop over the days while the cold and snow reign outside!
Preventing shrinkage with good lighting
Not all seeds need light to germinate, but young plants do not. As soon as the germ emerges from the soil, we must provide it with the amount of light it needs if we want to produce robust plants. When the lighting is insufficient, the seedlings grow proudly, stretching towards the light source like a baby bird craning its neck to receive food! This reaction to lack of light is called “etiolation”.
The symptoms of etiolation are:
- internodes of exaggerated length
- thin and brittle stems
- a less intense green
- smaller and fewer leaves
To succeed in their seedlings, a lucky few will only need a very sunny window, but too often, the sunlight that enters through the windows of the house is insufficient. Even when the light is good, as it only comes from one side, the plants lean towards the window. So that they can develop uniformly, we must then turn the pots every day by 90°, always in the same direction. Also, unless you have the good fortune of owning a greenhouse, the installation of a lighting system is almost always necessary. We recommend our blog post by Martin Lejardinier who looks into the question.
The quantity and quality of light are very important factors in the success of seedlings.
In terms of quantity, the seedling trays must receive light over the entire surface. A good method is to bring the light source as close as possible to the young shoots. Depending on the light source, a distance of 5 to 7 centimeters is recommended. To bring light and seedlings closer together, you can opt for a system of removable hanging lamps whose height can be adjusted. With fixed lamps, these are the trays that can be moved up and down as the plant grows.
In terms of quality, a temperature of 6 kelvins, which corresponds to a rather bluish light, is ideal.
From the moment the seeds emerge, the young plants must be lit for 14 to 16 hours. The use of a minuterie avoid forgetting.
Ventilation is good!
Another tip for successful sowing is to expose the young seedlings to a current of air using a small ventilateur set to low speed. This practice has two major advantages:
- it allows good ventilation around the plants, which helps prevent diseases caused by excessive humidity; And
- young seedlings thus exposed to the wind develop a superior cellular structure at the level of the stem and leaves, which greatly facilitates their acclimatization outside, when the heat returns.
Watering rhymes with dosage
Watering may seem trivial, but sometimes water that is too cold gives your young plants unnecessary shock. It is therefore recommended to fill your watering container and let it sit for 24 hours before using it.
Here are some basic instructions:
- water in the morning to give the soil time to dry a little before night;
- moisten the potting soil without soaking it to avoid problems with rot and damping off;
- if the container is in a saucer, it must be emptied immediately after watering, when water accumulates there;
- spray or water in fine rain so as not to make holes in the soil.
A little warmth, please
Also, we too often forget that the interior of our homes in winter is not warm enough to allow optimal germination of several varieties originating from warm regions. This is particularly the case for tomatoes, peppers, eggplants, cucurbits (cucumber, melon, etc.). A good number of them require a soil temperature above 18°C, such as cucumbers and tomatoes, which require a temperature of 26 to 34°C to germinate well. A heating mat provides such temperatures in the substrate and a thermostat which adapts to this mat allows you precise adjustment of the temperature between 20° and 42°C.
Good potting soil and clean pots
Before adding potting soil, make sure your containers are clean to avoid exposing your seedlings to pathogens. You will then fill them with a potting soil ready to use. Seedling mixes are expressly designed to facilitate germination. They have a good balance between moisture retention and drainage to limit the incidence of damping off and crown rot.
These new soils are disease-free; When they are used, recycle them in the compost heap or at the foot of trees and shrubs in the garden. Do not use them a second time for seedlings, as they could be contaminated, not to mention that their initial draining and nutritional qualities are no longer the same.
These potting soils are made from sphagnum peat moss to which manufacturers add various ingredients such as peat humus, coconut fiber, perlite, lime, gypsum, fertilizers and mycorrhizae.
And to obtain even more vigorous plants, why not add a little extra touch to make your soil lively? You will see, it is very simple to do, we explain the reasons to you and we give you Jean-François' recipe in this recent post.
- 22.02.2023: update of the article 'It's sowing time!' published in March 2019. Modification of the title, replacement of words and expressions here and there, modification of the sections on lighting (and deletion of the paragraph on neon lights) and heat.
