Planting a cold frame correctly: professional tips on cultivation, model and vegetables

Planting a cold frame correctly: JUWEL professional tips on cultivation, model and vegetable selection

Be the first to welcome spring to your garden: If you're already raving about your own fresh vegetables, crisp salads, or healthy spinach in winter, a cold frame is the perfect way to kick-start the gardening season. But growing in a cold frame is equally about the heart and mind. You bring the passion, we bring the knowledge: With our best professional tips on growing, model, and vegetable selection, growing your favorite varieties will be child's play.

Contents:

Function and advantages of a cold frame
Mini cold frame, growing box or as a raised bed combination
- Which cold frame model should I choose?

Important questions about planting in advance
Mini cold frame or growing box?
Cold frame-raised bed combinations

The right location for a cold frame
The optimal soil for a cold frame
Creating a cold frame: What you should consider
Properly care for, water and ventilate your cold frame
Which vegetable should you plant first? Your personal sowing and harvest calendar

The most important things about planting a cold frame correctly in brief

A cold frame gives you a head start on the gardening season by protecting your plants from the cold and creating ideal growing conditions. Choose a model that fits your space—whether it's a mini cold frame, a propagator, or a combination of a cold frame and a raised bed, such as the Timber Raised Bed 2-in-1 Propagation Kit or the Timber Raised Bed Combo Kit .
Provide a sunny, sheltered location and nutrient-rich, loose soil that retains heat well. Regular watering, aeration, and crop rotation will ensure your cold frame produces abundant yields throughout the year.
Start early with hardy crops like spinach, radishes, or lamb's lettuce, and use a sowing calendar to optimally plan your harvest.

Function and advantages of a cold frame

A cold frame is a covered growing area that offers an easy way to start growing vegetables and lettuce even in low temperatures and to enjoy the harvest in spring.

Gardening in a cold frame works like a mini-greenhouse. It creates an ideal microclimate for your plants because the protected bed absorbs the sun's warmth. The soil and air warm up, and the released heat can't escape as quickly. Therefore, it's always warmer in a cold frame than outside. Tender seedlings thrive under the protective cover of a cold frame while winter chills still reign outside.

A cold frame can be used almost 365 days a year. In spring, it's ideal for pre-cultivating vegetables like spinach, radishes, and lettuce. It's also ideal for growing fruits and vegetables continuously, as it protects the plants from extreme weather conditions. In winter, you can even grow and harvest winter lettuce and other cold-resistant plants.

In short, cold frames are

Designed for optimal conditions: With a cold frame, you can outsmart nature's natural rhythms and get started weeks before the usual gardening season. You can start growing vegetables and herbs as early as February or March.
Made for plants with patience: Vegetables with a long growing period, such as leeks and celery, benefit enormously. They germinate in a protected environment, are carefully pricked out, and later transplanted outdoors – hardened and perfectly prepared for everyday gardening.
Designed to be flexible and space-saving: Whether in a spacious garden or a small space, as an indoor propagator or a classic outdoor growing area, the cold frame is versatile. Cold frames are available in all sizes and for all outdoor spaces. They offer beginners and professionals alike the opportunity to allow plants to thrive in a protected environment.
Designed for higher yields: The extended growing season allows plants to benefit from optimal conditions. In the thermally insulated environment, your young plants defy wind and weather and can devote themselves entirely to their growth.

Mini cold frame, growing box or raised bed combination - which cold frame model should I choose?

Choosing the right cold frame model depends on your intended use and the available space in your garden. A homemade wooden frame, for example, has the advantage of being easy to dismantle after the growing season and store in a dry shed. While solid cold frames are significantly more durable, their location should be carefully considered. High-quality cold frames have the advantage of being equipped with integrated ventilation systems that are optimal for young plants, such as continuously opening windows or automatic window mechanisms.

Depending on your space and needs, you should consider some options and examine the different models.

Important questions about planting in advance:

How big should your cold frame be? Depending on the size of your garden and the amount of space you have available, the space for a cold frame is also limited. Most cold frames are about 1 to 1.5 meters wide. Some of our JUWEL models offer space for your young plants over a length of 2 meters.
What material do you want to invest in? Since the cold frame will be used primarily during the cold season, it should be able to withstand all weather conditions. After all, your plants depend on stability. A weatherproof and rust-proof metal frame is therefore essential. You have several options for the walls: from durable glass and acrylic glass to self-attached film and high-quality polycarbonate hollow-wall panels. It's important that the material is transparent and UV-permeable, has sufficient wall thickness for heat regulation, and has integrated ventilation openings for temperature and humidity control.
What vegetables do you want to plant? Do you want to plant only frost-sensitive vegetables in the cold frame in the spring, or continue using the cold frame when your vegetables move to the raised bed or garden in the summer? Perhaps you also want to give your winter vegetables a home during the cold season? Depending on your plans, you may only need a mini cold frame, a propagator or seed trays, or a combination of a cold frame and raised bed for larger gardening projects.

JUWEL Tip: Cold frames are also perfect as homes for turtles . This way, the animals are protected from birds and have a beautiful home in the spring to gently awaken from hibernation.

Once you've carefully considered your priorities for a cold frame, you can decide on a model. An overview of the most common models will help you choose.

Mini cold frame or growing box?

A small mini cold frame or a propagator is designed for small gardens, balconies, or even windowsills. These compact tools are easy to use, especially for beginners, and ideal for herbs or lettuces. You can either find them in the garden department of your hardware store as propagator trays, or if you're handy, you can simply build a propagator yourself. If you're not quite as skilled as you might be, you can find good instructions online here.

Advantages:

Designed for small space requirements.
Made for beginners and apartments without a garden.

Disadvantages:

Not all models are designed to be environmentally friendly.
DIY solution is intended for gardeners with manual skills.

JUWEL tip:
Designed for early birds in the garden: With the Timber raised bed cultivation set 2 in 1 Take advantage of the benefits of a sturdy propagation box while enjoying the consistent, ideal conditions of a JUWEL raised bed. The Timber raised bed combo set is also the perfect choice for your journey from sowing to harvest: It combines a heat-insulating Timber raised bed with the weather- and frost-resistant 130/60 thermal cold frame .
Both combinations not only offer you a space-saving solution, but also the opportunity to expand your kitchen garden with additional JUWEL raised bed elements as desired, thus maximizing yields all year round.

The JUWEL Premium Cold Frame Biostar Protect 1000 , with its one-meter width, is ideal as a space-saving solution for small gardens. The Easy Fix 100/60 and Easy-Fix 120/100 cold frames are also suitable. give you high yields in a small space. You can even retrofit a window-mounted automatic system that automatically regulates the heat.

Cold frame-raised bed combinations

Otherwise, we'd say: Nothing whole is nothing good. In this case, the exception proves the rule: For holistic year-round vegetable and plant cultivation, there's nothing more practical than a combination of a cold frame and a raised bed. This provides the young plants with stable protection from cold and wind. At the same time, the raised bed provides the young plants with even more warmth, as the soil in the raised bed warms up faster than the ground. Once your vegetables have moved into the raised bed, you can use the cold frame attachment to grow winter vegetables.

Advantages:

Made for seedlings and young plants.
Intended for year-round projects.

Disadvantages:

Higher costs may apply as it is intended for larger purchases.
Not made for indoor use.

JUWEL Tip: Our Thermo Cold Frame 200 is designed for all raised beds measuring 200x100 cm – regardless of whether they are made of wood, metal, plastic, or WPC. This way, your young vegetables in the Thermo Cold Frame have the perfect place to sprout with the first rays of sunshine and an optimal habitat once the greenery is strong enough and the weather is more stable.

The Timber raised bed for patios or balconies is designed for gardeners without a garden and can also easily be installed in other open spaces. Upgraded with the 130/60 thermal cold frame , you're optimally positioned for all seasons and can harvest year-round.

The right location for a cold frame

The location of your cold frame is crucial for your yield. Here are some things you should pay particular attention to when setting up your cold frame:

Sunny location: Place the cold frame in a spot that receives at least six hours of sunlight. The south-facing side of your garden or balcony is ideal. Make sure hedges or neighboring houses don't cast shadows on it.

Wind protection: Place the bed in a sheltered location. A hedge or wall could help. However, as mentioned above, it should not cast a shadow. Alternatively, a cold frame with glass or polycarbonate walls provides optimal wind protection.

Good drainage: Make sure the cold frame isn't located in a depression to avoid waterlogging. A slightly elevated location is optimal.

The optimal soil for a cold frame

The choice of soil significantly influences the growth of your plants:

1. Nutrient-rich soil: Mix garden soil with compost to create an ideal base for growing plants. You can naturally create your own compost in the garden or kitchen , thus comprehensively supporting nature's natural cycle. Alternatively, you can also purchase special potting soil commercially. This is usually looser and contains important nutrients.

Garden and kitchen should be linked to the composter range

2. Loose and permeable: It's important that the soil has a loose structure to ensure good air circulation, so the roots receive enough oxygen and develop optimally. This also prevents waterlogging.

3. Heat storage: As already mentioned in the section on location, a layer of manure or leaves under the soil supports the warm base of the cold frame if you place it directly on the garden soil.

JUWEL additional tip: Renew the top layer of soil under your cold frame after each season to compensate for nutrient losses and keep pests at bay. Crop rotation also plays an important role in achieving high yields—especially in raised beds. Learn in detail how crop rotation and crop rotation work in raised beds in our article XY. (Insert if a suitable article has been written.)

Creating a cold frame: What you should consider

Ready to set up a cold frame and get started? Even gardeners with green fingers need some preparation before construction. The key is humus-rich garden soil that's been carefully weeded and loosened.

Step 1: Prepare the bed

Remove weeds and loosen the soil.
The warmer the soil temperature, the more stable the seedlings will thrive. Apply organic matter such as manure or leaves and cover them with soil. This layer creates natural soil heating. A two- to three-centimeter-thick layer of stinging nettle and comfrey mulch or a permeable fleece is good for suppressing weeds.
Pro tip: A 30-centimeter layer of horse manure and another 20-centimeter layer of soil enriched with other organic materials such as potting soil and compost acts like a natural heater. It increases soil temperature and promotes plant growth.

JUWEL Tip: The JUWEL Easy-Fix 120/80 cold frame is designed for pallet collars and is ideal if you want to build your very own, cost-effective raised bed/cold frame combination. If you don't have enough manual skills, the Thermo-Cold Frame 130/60 is also available. the right home for your young plants. You can place this on JUWEL Timber raised beds.

Step 2: Frame and cover

Set up the cold frame and attach the cover. Good models include solid galvanized steel ground anchors. Ensure a good seal against the ground to minimize heat loss. Hinged models make handling easier.

Step 3: Planting plants

Plant hardy crops like spinach, lamb's lettuce, or radishes first. Keep enough space between them to allow the plants to grow well. More on which vegetables belong in the cold frame and, especially, when—more on that later.

Properly care for, water and ventilate your cold frame

Once the first shoots show their bright green, almost nothing can go wrong. However, there are a few things you should keep in mind along the way and to ensure your continued health.

Lots of attention and water at the right time

Care for your cold frame with love and attention. Water in the morning rather than the evening. Plants dry out better during the day. This prevents waterlogging. Watering in the evening also encourages snails to move in. The water shouldn't be too cold to avoid growth shock on warm days. Water from a watering can or water barrel is ideal. Try to water the soil between the plants whenever possible. Leaf fungi like powdery mildew spread more quickly on damp leaves.

Regular ventilation

Keep the temperature at a comfortable 22 to 25°C (72 to 77°F) – this will ensure your seedlings thrive. Regular ventilation is essential, however, to prevent mold. Even a wooden board as a spacer protects against heat on warm days; for a more professional solution, use special ventilation levers or sliding windows. If you're looking for a little more luxury, let an automatic window mechanism do the work – it knows when your plants need air.

Pay attention to the outside temperature

Protect your bed from sudden cold snaps with an additional cover such as horticultural fleece. Quality cold frames have thick, hollow-core panels to keep out wind and cold.

Which vegetable should you plant first? Your personal sowing and harvest calendar

While a cold frame allows you to advance the gardening season by several weeks, the ideal time to start still depends on the climate:

Mild climate: The first crops such as radishes or spinach can be sown as early as February.
Colder climates: It is better to wait until March or to protect your cold frame with fleece on very cold days and in frosty weather.
The soil temperature at the start of sowing should be at least 14°C.

JUWEL additional tip: When the days are still short, the JUWEL LED light is perfect for an extra burst of light. Solar-powered and environmentally friendly, it blends seamlessly into your cold or raised bed, promoting growth and ensuring even germination.

Cold frames are designed for fast-growing crops. These vegetables are ideal:

Radishes are ready for harvest after just 4 weeks.
Lamb's lettuce tolerates low temperatures and germinates quickly.
Spinach is also ideal for the start of spring.
Early varieties such as lettuce grow quickly and tolerate cooler temperatures.

Once these crops have been harvested, you can use the cold frame for summer vegetables.

This is how the cold frame joy continues throughout the gardening year:

Tomatoes, peppers, zucchini, cucumbers and melons are frost-sensitive vegetables that prefer late spring.
Cucumber and melon season is from May to August. Transplanting is laborious, but there's room in the cold frame for a new row. Kohlrabi, radishes, and lettuce are pricked out when they're large enough to handle.
Winter vegetables such as kale and leeks can be planted until September and even harvested during the winter in the snow.
You can sow robust cabbage varieties again in the cold frame starting in autumn, as the falling temperatures make it attractive to use for various vegetables again.

Note the sowing and harvest dates to improve your planning for the entire gardening year. Your personal JUWEL Sowing and Harvest Planner for the kitchen garden will inspire you all year long: