Sowing seeds under frames is essential when the cold is still very present or quite simply when spring frosts are to be feared. This technique simply makes it possible to sow in a sufficiently warm environment, which is essential to promote the germination of a large number of seeds. Let’s see what a frame is made of, and at what time of year it is necessary to sow seeds in it.
What is a chassis?
The chassis is a device that allows keep the growing medium warm and in any case protects it from frost but also from pests. This structure is essential for promote seed germination et accelerate plant growth.
We are talking more specifically about cold frame since no heating device is installed there. It consists of a rigid frame (in wood, iron, etc.) and glazing. It fulfills the same role as a tropical greenhouse.
Make a frame with recycled materials
We can easily build a frame makeshift either with bricks, or with wooden planks, cleats or with the help of an old pallet (if possible untreated and unpainted) as well as glass plates such as the panes of old doors stored in the depths of the garage and finally some hinges.
We take care oftilt the glazing on the one hand to facilitate the flow of rainwater outside the structure so as not to drown the seeds. A tilt of the order of 5 centimeters per meter is quite suitable since, on the other hand, the penetration of the light rays being favored by this angle, the seedlings profit from a maximum of luminosity. To create a homemade chassis is really economic and also represents a good solution for recycler what you no longer want to use. So it’s a great way to give a second life to what we had planned to drop off at the local recycling center.
Note that the chassis being made of a durable material, it is more ecological that the plastic tunnel especially as it can quickly tear in the event of strong wind, that it promotes condensation because the ventilation is not sufficient and that its transparency deteriorates over time. Admittedly fragile, glass therefore ages better than plastic. It also has the advantage of creating a beneficial greenhouse effect for seedlings since the heat remains well inside the glass structure.
Nothing prevents you from creating a frame whose walls are also glazed. Under this bell framecrops benefit from maximum light.
What time of year to sow under frame?
When you have to perform early sowingthe chassis is essential, that is to say Starting from February usually. However, at that time, in our latitudes, the soil in the garden was not warm enough to accommodate seeds which could not therefore germinate in such conditions. They can be ornamental plants as well as vegetable plants. The seeds needing heat, they cannot be exposed to harsh winter conditions or even the slightest risk of spring frost.
Sowing under frame can extend well beyond February. In our regions where the winters are particularly harsh and tend to drag on, sowing under frames is unavoidable and even in March or April for all the seedlings which should only be transplanted from May, in soil sufficiently warmed by Sun rays.
Precautions to be taken when sowing under frame
You have to think about open the frame on very sunny days because under the windows, it may be too hot. The seedlings being still very fragile, they would only burn out and all the work would then have to start again. We simply use wooden wedges of different sizes to adjust the degree of opening according to the outside temperature and that the ventilation of the frame is beneficial to the plants. Of course, we don’t forget to close the frame at the end of the afternoon because the temperatures drop very quickly at this time and there is no question that the seedlings will catch a cold snap. The plants remain stunted if they lack heat and this can even be fatal to them.
Another precaution to take so as not to see the young plants wither: take care of watering. Under glass, the growing medium dries much faster than outdoors. It is therefore essential to ensure that there remains moist enough so as not to lose all the seedlings. Ideally, the ground must be moist all the time. Too wet it becomes sticky or even muddy creating asphyxiation of the seeds, and favoring parasitic attacks. If you overwater your growing medium under the frame, you also increase the risk of rotting, and the seeds may even be rotten before they have started to germinate.