Planting in greenhouses: best plants to grow - Plantura (2024)

When it comes to greenhouse gardening, a variety of questions may arise when starting out, and that is especially true for beginners. In this article, you will learn how to use a greenhouse efficiently and plant in it all year round.

When planting in a greenhouse, questions regarding ideal planting times and which plants grow well together can quickly come about. Below we will answer all these exciting questions on when, how and with which plants you can design the inside of your greenhouse for optimal growth.

When can you start planting in greenhouses?

Generally, planting in a greenhouse can be done all year round. In contrast to commercial vegetable growers, glasshouses in the garden do not tend to be heated – they are so-called cold frame greenhouses. Planting in the greenhouse should therefore always be adapted to the respective season and temperature. Nevertheless, even in winter, plants are far better protected from the weather and frost than in the open air. At the same time, glasshouses heat up more quickly when the sun is shining and maintain higher temperatures a few hours longer into the night.

If you want to plant in a plastic greenhouse, bear in mind that plastic provides much less insulation and does not retain heat for as long when exposed to sunlight.

In spring, the first spring crops can be planted from February onwards. From early to mid-May, the main crops such as tomato(Solanum lycopersicum), cucumber(Cucumis sativus) and pepper (Capsicum annuum) follow. From September to October, succeeding crops with cold-tolerant vegetables are recommended so that you can use the greenhouse effectively.

Greenhouse planting: schedule and plan

Drawing up a planting layout for your greenhouse is a good way of calculating how many plants will actually fit inside with sufficient plant spacing. In addition, you can then use these annual records later to see which species grew in which locations, so that other vegetables can be planted next year.

Growing peppers, cucumbers, tomatoes and aubergines (Solanum melongena), all Solanaceae, in the greenhouse together is a common combination. From the point of view of a balanced mixed culture, however, this pairing is far from optimal: nightshade plants are susceptible to similar diseases. Some pathogens survive in the soil and infect the next plants as well. At the same time, they are all heavy feeders, so they demand large amounts of nutrients and water from the soil.

A pre- or post-cultivation with completely different plant species acts as a soil cure and prevents leaching. In addition, soil-borne pathogens can only accumulate to a limited extent.

Suitable for pre-cultivation from February onwards:

• Endive (Cichorium endivia)
• Lamb’s lettuce(Valerianella locusta)
• Kohlrabi (Brassica oleracea var. gongylodes)
• Cress species
• Broad beans (Vicia faba)
• Radish(Raphanus sativus var. sativus) and black radish (Raphanus sativus var. niger)
• Lettuces such as butterhead lettuce(Lactuca sativa var. capitata) or curled lettuce(Lactuca sativa var. crispa)
• Spinach(Spinacia oleracea)

Tomatoes and cucumbers are also considered poor neighbours because they do not complement each other well in growth and requirements but rather compete. Good companion plants are important for soil health and reduce disease and pest pressure. Ideally, unfavourable neighbours are planted with sufficient spacing and mixed with well-tolerated crops. Some combinations are space-saving and have proven successful when planting in the greenhouse.

Companion planting in a greenhouse: which plants grow well together?

• Tomato, parsley(Petroselinum crispum) and basil(Ocimum basilicum)
• Cucumber, French beans (Phaseolus vulgaris) and dill (Anethum graveolens)
• Aubergine and marigold(Tagetes)
• Peppers and okra(Abelmoschus esculentus)

Tip: always ensure a sufficient supply of nutrients for heavy feeding vegetable plants, as this prevents deficiency symptoms and sickly growth. Because the nutrients in a predominantly organic slow-release fertiliser, such as our Plantura Tomato Food, are released slowly over several weeks, it is only applied twice a season. This ensures that the plants receive gentle and even fertilisation.

Autumn greenhouse planting

Autumn planting in the greenhouse not only rewards you with vitamin-rich food in the cold months but also stimulates soil life, prevents the soil from drying out over the winter, and has an overall beneficial effect on the soil structure and humus content. Autumn planting also counteracts soil fatigue. From September to October, some suitable follow-up crops for the heat-loving main crops (tomatoes, peppers, etc.) are:

• Yellow rocket (Barbarea vulgaris)
• Leaf mustard species such as mizuna (Brassica rapa subsp. nipposinica)
• Lamb’s lettuce
• Autumn and winter radishes
• Autumn turnips (Brassica rapa subsp. rapa subvar. esculenta)
• Tatsoi(Brassica rapa convar. narinosa)
• Winter purslane(Claytonia perfoliata)
• Sugar loaf chicory(Cichorium intybus var. foliosum)
• Green manuringwith mustard(Sinapis), phacelia(Phacelia) etc.

Instructions: planting a greenhouse correctly

As the space is limited in a greenhouse, it is important to make optimal use of the space while also ensuring that all the plants inside are sufficiently spaced apart and no area remains unused. A staggered arrangement has proven successful if there is enough space for a two-row planting. The tall-growing tomatoes and cucumbers are placed against the walls of the greenhouse, while the smaller plants such as bushy peppers, chillies or herbs are planted near the paths. This way, all plants can be easily reached and cared for from the centre. The tall-growing vegetables can also be guided upward and tied to the vertical beams of the greenhouse. Despite the limited space available in the greenhouse, it is important to ensure good air circulation by never planting your crops too densely. Otherwise, high humidity can quickly lead to fungal diseases, which is why it is also important to keep the ventilation windows clear when planting in a greenhouse.

Greenhouses come in a wide variety of designs, but the basic structure usually remains the same.