Is your neighbor always ahead with magnificent plants? Then it's probably because of his cold frame. In this inconspicuous box, the plants thrive from February onwards. This guide explains how to properly set up your own cold frame.
How do I set up a cold frame correctly?
Creating a cold frame correctly means choosing a model that slopes towards the south, maintaining a maximum width of 100 cm and installing natural heating. To do this, dig a 50 cm deep pit, fill in horse manure and garden soil to create ideal growing conditions.
Simple functionality – different model variants
The cold frame works like a mini greenhouse. So that seedlings and plants can thrive here from February/March onwards, the sun's rays and a special filling ensure sufficient heat, which is retained by a movable cover. If you only rely on the sun's rays as a heat source, use side panels and covers made of transparent material, such as double-wall sheets. If you integrate natural heating into the structure, the side panels can be made of wood. The following models are suitable for cold frames:
- Wooden frame with disused windows as a cover
- Frame and cover made of glass or plastic
- Aluminum box with plastic lid
- Cold frame tunnel made of weatherproof, transparent film
If you are designing your box-shaped cold frame correctly, use a model with a slight southward slope. This means your plants can still benefit from the light even when the sun is low. In addition, rain runs off more quickly. For good ventilation, it is important that you can put the lid up. Powerless ventilation openers (€23.00 at Amazon) automatically provide fresh air when a certain temperature level is exceeded.
Flexible dimensions – this is what you should pay attention to when it comes to width
The dimensions of a cold frame are based on the space capacity. The more space is available, the longer the box or polytunnel can be. The width, however, should be limited to a maximum of 100 cm so that you can easily reach all plants from the edge.
Centerpiece under construction – filling as natural heating
A cold frame functions as a cold frame when only the sun acts as a heat source. By integrating a sophisticated filling into the structure as a natural heater, you can optimize your cold frame into a warm frame with an extra long service life of up to 365 days. Before setting up the frame structure in the garden, prepare the site as follows:
- Dig a 50 cm deep pit in a sunny location
- Line the sole with vole wire and a 5-10 cm thick layer of leaves
- Pour a 20 cm thick layer of horse manure
- Place a 20 cm thick layer of garden soil, compost, green waste and horn meal on top
The decomposition process of the filling creates a temperature of 18 to 22 degrees Celsius in the tightly closed cold frame within 8 to 10 days. These are the ideal conditions for sowing and planting while it is still bitterly cold outdoors.
Tip
Upcycling of Euro pallets is very popular in order to conjure up furniture or flower boxes. Resourceful home gardeners can easily build a cold frame themselves from old or new pallets. With a little craftsmanship, the wooden transport supports can be converted and provided with a transparent cover.
