Most of the time people browse the web in order to find what to grow in a garden, indoors or in a greenhouse. However, whilst everyone advises what grows best in certain conditions, it can be challenging to find what doesn’t do so well, for example, in a greenhouse.
The suggestions on what plants not to grow in a greenhouse are based on a variety of factors. For instance, is a greenhouse space will be enough to grow certain types of plants? Are these types of plants enjoying the environment created in a greenhouse structure? In this post we are going to talk about different plants and why you can’t grow them in a greenhouse.
What can you not grow in a greenhouse?
Hardy Spring Bulbs – Hyacinth, Narcissus (Daffodil), Tulip.
You need to start hardy spring bulbs outdoors and then you can bring them in a greenhouse for display. After planting bulbs need a period of complete darkness and a temperature of around 40°F (4°C). The best way to create these conditions is to move the pot in the garden and cover it with 4 inches of peat.
So, why do these bulbs don’t do well in a greenhouse? Let’s take a Tulip, for example. It needs cool conditions which makes Tulip a perfect flower for a spring garden. However, if you choose the right sorts, you can extend growing season and plant Tulip bulbs in a greenhouse in September-October. That way you can see them flowering in January to April.
Root vegetables – Turnips, Carrot, Beetroot, Onion, Sweet Potato, Ginger, Garlic, Radishes, Fennel, Celeriac, Turmeric, Potatoes, Rutabaga.
It is better to grow root vegetables in the garden because they benefit from the sowing directly in the ground. That way root vegetables will grow strong and the roots are not going to be obstructed. As a general guidance, tender types of vegetables can die outdoors, so you need to sow and harvest them in a greenhouse.
For example, if you sow cucumbers seeds indoors and then transplant seedlings outdoors, it can lead to wilting and dying of cucumber plants. So in this case it is better to directly plant cucumber seeds where you want them to grow.
Other vegetables are half hardy, for example, cauliflower, celery, chard, chicory, Chinese cabbage, endive and lettuce. So if you want to extend growing season for these vegetables, keep them in a greenhouse. The last type of vegetables are hardy vegetables which grow best outdoors.
Hardy vegetables – broccoli, Brussels sprouts, cabbage, collard, kale, kohlrabi, leek, onion and spinach.
Hardy vegetables benefit from the outdoor conditions. Also, watering can be quite tricky in a greenhouse. You can easily forget to do it and plants will begin to wilt. When growing outdoors, plant roots can get nutrients and water from the soil. So, it is easier to grow some vegetables in the garden.
However, some varieties of hardy vegetables can produce early crop when planted in a greenhouse. Keep in mind that you need to select varieties suitable for greenhouse cultivation. Generally, what you can do is to start the seeds in a greenhouse from January or February and plant them out when soil is suitable.
Fruit – citrus trees and kiwi fruit
Lemon and orange trees are best grow outdoors and then moved to greenhouse, conservatory or in your home for display. First, they need humidity of 50% or above. Second, they benefit from plenty of air movement outdoors.
Third, you don’t need to worry much about watering outdoors. When citrus trees lack water, the leaves start to curve under in order to conserve moisture. Next, citrus trees grow well in the ground when they can easily reach nutrients. However, you still need to test the soil and add compost to prevent nutrient deficiencies.
Finally, citrus trees need sunlight to thrive. On average, you need to provide them with a minimum of 8 hours a day of sunlight. Ideally, to bloom and have the strength to produce fruit, orange and lemon trees need up to 12 hours of sunlight a day.
Also, if you want to grow citrus trees from seeds, they will not root until they reach the optimal height. Which is most of the time too large for a hobby greenhouse. However, if you dream to grow fruits in a greenhouse, you can choose a variety for greenhouse growing that is going to bear edible fruits. For example, ‘Satsuma’ oranges or ‘Meyer’ lemons.
Why not to grow kiwi in a greenhouse?
Although it is relatively easy to plant new kiwi trees or shrubs, for a greenhouse growing it is not a really good idea. This plant is a vigorous climber and leaves are very big in size meaning that it can create shade in a greenhouse. That can be challenging to manage when you grow other plants too.
Of course, if you really want to, you can grow the vines in a greenhouse or conservatory, but you need to keep them in check. That includes daily pruning. That is why kiwi is not common in greenhouses and you can use the structure more efficiently. If you want to grow something exotic, why not to give a go to succulents, for example, you can grow cacti in a greenhouse.