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Cold frame in the garden: How to use it optimally
Cold frame in the garden: How to use it optimally
Video: Cold frame in the garden: How to use it optimally
Video: Gardening expert Mark Cullen gives tips on using cold frames 2023, February
Anonim

While winter is on its last legs, the first plants and vegetables begin to grow in the cold frame. At least four weeks before the garden really starts, you can sow lettuce, spinach, radishes and kohlrabi in the mini greenhouse. Here we tell you what you should pay attention to, what grows when and how you build a cold frame.

Table of contents Table of contents cold frame in the garden: How to use it optimally

  • benefits
  • disadvantage
  • Planting calendar
  • Prefer young plants
  • Cultivation method with natural heating
  • Build a cold frame: how it works
  • Location and ventilation
  • Tip: convert raised bed into cold frame

Table of contents Table of contents cold frame in the garden: How to use it optimally

  • benefits
  • disadvantage
  • Planting calendar
  • Prefer young plants
  • Cultivation method with natural heating
  • Build a cold frame: how it works
  • Location and ventilation
  • Tip: convert raised bed into cold frame

Beat frost and weather by delaying the growing season of vegetables and plants with a cold frame for many weeks and extending them until the beginning of winter. The first early vegetables are already growing in this mini greenhouse, while frost, snow or storms still prevent sprouting in the garden. Such a small-scale greenhouse has always been part of the permanent inventory of many kitchen gardens. It costs relatively little and, depending on the model, fits on the smallest usable area. Regardless of whether you choose a kit from a hardware store, a self-made cold frame made of wood or a solid model made of masonry: what is important is the orientation to the sun, sufficient warmth in the floor and good ventilation on warm days. Once the cold frame has been built, it can be used 365 days a year.

Advantages of a cold frame at a glance

  • Makes an early start to the season possible in the garden.
  • Costs less than a greenhouse.
  • Also fits on small usable areas.
  • Saves space on the windowsill, where otherwise vegetables, salads, herbs or flowers are preferred.
  • Plants become more robust under glass and are better prepared for outdoor conditions.
  • Wooden or plastic models can be easily dismantled after cultivation and stored in the garden house or shed.
  • Solid cold frames with brick wall, clinker wall or concrete wall store the heat during the day and gradually release it to the plants at night.

Disadvantages of the cold frame at a glance

  • It heats up very quickly on sunny days - seedlings and young plants can dry up or burn.
  • Must be watered and aerated regularly.
  • Condensation or dirt on the panes may prevent sufficient light from entering.
  • If the roof pitch is not sufficient, the rainwater cannot run off and collects on the wooden frame.
  • Without adequate wood protection, the cold frame is quickly damaged by weather conditions and direct contact with the earth.

Plant calendar: what grows when in the cold frame?

A cold frame is suitable for the pre-cultivation of vegetables and young plants in spring as well as a summer vegetable garden in small format. Even in the cold season, winter salads such as endive and lamb's lettuce thrive in it. In December and January it offers a protected place for storing root vegetables or overwintering potted herbs.

month

Cultivation

Direct sowing

plants

February

Broad bean, chilli, Paprika, salad, savoy cabbage

Garden cress, radishes, Radish, spinach, stem sauce

Picking and cutting salad

March

Sweet peas, peppers, Salad, summer flowers, tomatoes

Early carrots, kohlrabi, chard, Radish, radish, arugula, Salad, spinach, pea

Salad, onions

April

Eggplant, cucumber, Summer flowers, Summer salad varieties, zucchini

Basil, dill, cress, Radishes, arugula, lettuce, chives

Celery, tomato

May

French bean, leek, Melon, celery

salad

Eggplant, cucumber, bell pepper

June

Kale, lettuce, Winter hedge bulb

Garden cress, radishes, Radish, spinach, stem sauce

Picking and cutting salad

July

Sweet peas, peppers, Salad, summer flowers, tomatoes

Early carrot, kohlrabi, chard, Radish, radish, arugula, Salad, spinach, pea

Salad, onions

August

Eggplant, cucumber, Summer flowers, Summer salad varieties, zucchini

Basil, dill, cress, Radishes, arugula, lettuce, chives

Celery, tomato

September

Corn salad, radishes, spinach, Winter purslane

Picking and cutting salad

October

Corn salad, carrots, Winter purslane, radishes

Winter salad varieties

Prefer young plants in the cold frame

In addition to sowing vegetables and herbs, the cold frame also makes it possible to grow frost-sensitive young plants or summer flowers, which later migrate into the vegetable or flower bed. Even early seedlings of kohlrabi and salads, which can be bought early in nurseries, come under the hood and deliver the first harvest results after just a few weeks. If the cold frame is free again after pricking off the young plants, sowing starts again.

Tip: If you plant your seeds or seedlings in multi-pot plates made of wood or coconut fiber and sink them a little into the ground, the growing soil is heated up by the rotting process in the subsoil.

Jungpflanzen im Frühbeet
Jungpflanzen im Frühbeet

Young plants can quickly burn or dry up in the cold frame on sunny days. Make sure that you ventilate regularly.

Photo: Friedrich Strauss / NouN

Cultivation method with natural heating

A cold frame is basically a small greenhouse with biological underfloor heating: installed under the garden soil, a layer of manure from horses or cows provides warmth in the plant bed. If it is pure animal manure, you should first mix it with straw or leaves in a ratio of 1: 1. Carbon dioxide and heat develop during the decomposition of the nitrogen-rich horse manure. Both migrate upwards into the substrate and provide the seedlings with optimal conditions for germination and growth.

Tip: After filling in the horse manure, wait around a week before you start sowing. This allows the floor in the cold frame to warm up well.

If you don't have manure available, you don't have to do without a protective cold frame for your plants. Also in February, sowing is possible in a so-called cold box. This is only filled with seed soil and protects the seeds like a small greenhouse. Coarse compost or shredded kitchen waste such as apple and potato peels, which are distributed generously, lures useful soil creatures out of hibernation. So that the soil warms up well, you should close the glass cover with this variant two weeks before sowing for the first time. As soon as the days get longer and the soil in the cold frame has warmed to at least 7 to 10 degrees Celsius, you can sow the first crops such as cress, radishes and spinach as well as local herbs, such as chives or pimpinelle.

Tip: In very cold winters, it is advisable to insulate the side walls of the cold frame from the outside with heaped leaves or straw in heavy frost. You can also sink the walls of the cold frame in the root area a few centimeters deep for insulation.

Build a cold frame: how it works

If you do not want to use a commercially available kit for a cold frame, but want to build an individual mini greenhouse, you can choose the dimensions depending on your own space. Our tips: The height of the wooden frame should be at least 32 centimeters at the front and 50 centimeters at the back - if young plants are also cultivated, preferably a little higher on both sides. The maximum depth is one meter, since you still want to get to the rear plants from the front. A roof pitch of 5 to 15 percent has proven itself.

You need this for a cold frame made of wood

  • 20 millimeter thick larch, oak or Douglas fir wood, spruce can also be used if necessary
  • plant-compatible wood preservative
  • old window sashes (if available and tight) or
  • Polycarbonate multi-wall sheets (more robust, better insulated against cold) or
  • Greenhouse film (inexpensive alternative)
  • 4 squares
  • 1 wooden strip in the selected width
  • 1 wooden strip as opener or
  • 2 chains to open the lid
  • automatic, currentless ventilation opener
  • Hinges
  • Screws
  • Compost and plant soil

Build a cold frame yourself

  1. Treat the wood with an ecological wood preservative.
  2. Use the squared timber to make a rectangular wooden box that is deeper in the front than in the back (32 centimeters in front, 50 centimeters in the back). With the lower long side, the cold frame faces south.
  3. If you have chosen multi-wall sheets or greenhouse sheeting as a cover: To stabilize it, attach a narrow wooden strip in the middle of the cover so that it connects the two longitudinal walls.
  4. Now fix the cover with hinges on the back, so that the lid can be easily opened to the rear.
  5. On the inside on the narrow sides, set the screws for the two chains so that the cover is slightly tilted backwards when open.
  6. To keep the lid open in warm weather, a short bar is attached from the inside to the front. Only screw it on one side so that it can be turned up.
  7. Alternatively, install the ventilation opener.
  8. Dig a hollow at the planned location according to the dimensions of your cold frame, one spade depth is sufficient. Spread about 15 centimeters of horse manure or semi-mature compost in it, followed by about 20 centimeters of plant soil. Make sure that the edges of the box are properly closed.
Belüftung Frühbeet
Belüftung Frühbeet

When building the cold frame, make sure that the ventilation is stable.

Photo: MSG / Christian Lang

Location and ventilation of the cold frame

Be sure to place the cold frame in a sunny spot in the garden. The lower long side should face south so that the bed can optimally capture and store the weak spring light.

But be careful: on sunny days, the cold frame gets hot quite quickly due to the limited space and good insulation. The temperature should not exceed 22 to 25 degrees Celsius - regular ventilation in mild weather is therefore a must. If it is too difficult for you to open the lid constantly and close it again after a few hours, we recommend installing an automatic window lifter, as is also used in greenhouses. It has a pressure cylinder in which liquid expands at higher temperatures and opens the cover. This allows fresh air to flow in as needed and to balance the climate inside the cold frame.

Tip: convert raised bed into cold frame

Happy who already owns a raised bed! Because this can be turned into a cold frame in no time at all. You only need a cover - the best thing is to remove it, so that the raised bed will be available as a normal vegetable bed again after spring.

  1. Saw two wedges with an incline between 5 and 15 percent along the length of the short sides.
  2. Mount this stacking frame firmly on the raised bed using wooden strips and screws. Align the lower side to the south.
  3. As a cover, fix old windows or multi-wall sheets or framed twin-wall sheets with hinges on the back of the top frame so that the lid can be opened easily.
  4. If you want to remove the cover later, you should convert the hinges so that you can remove the locking pin. Then the frame can stay on the raised bed all year round, but the cover must be removed in summer.
  5. Follow steps 5, 6 and 7 from the instructions above.
  6. To fill the raised bed, apply a layer of coarse material, such as branches and clippings, followed by finer green material, such as chopped material. This is followed by compost or horse manure on which you spread the plant soil.

Eva Bolta Redaktion Haus.de

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