Many different plants but more are outside than inside and something with watering the floor. That is some of the things Frederik from Udkansk has learned after his first season in the greenhouse. In addition to this he has also learned that there are limits to how many tomato plants a household of two need.

2021 has been our first year with a greenhouse in the garden. And what a joyful experience it has been and we have already learned a lot. We have a bunch of success stories but there are definitely also stuff we want to do differently next year. This is what is great about having gardening as a hobby - that you always bring some knowledge with you from the previous year.

In the beginning the greenhouse was for me a place for cultivation and the joy of plants. I made it clear to Nanna that the greenhouse was primary reserved for plants. I got wiser: The greenhouse offers much more than just a unique place to grow your love for plants. After countless evenings with card games, dinner, wine and social gatherings I have realized that the greenhouse first and foremost should be a living space. One does not exclude the other but since the greenhouse is 13 m² we had to prioritize which resulted in moving some of my many pots. It is important to have room to move around without you literally getting the lushness in your face or that you conveniently cannot sit down at the table. A way to have a spacious and intimate greenhouse is to have plants just outside the greenhouse rather than inside. Large bushes, small trees, climbing plants or tall perennials could be an option. So far we have built some tall plant containers on one side of the greenhouse and planted an evergreen hedge of thuja on the other side to provide shading. By being surrounded by vegetation in the greenhouse you get the same experience of lushness without it taking up space in the actual greenhouse.

Another benefit of choosing bigger plants near the greenhouse is that they can provide shade. It came as a surprise to how important shade is during summer. For small greenhouses like ours it can be extremely hot especially because our greenhouse is facing south, and therefore, the greenhouse plants get sunshine all day long. Even for plants who usually love the sun and warm temperatures it can be too much. Therefore, we have found it necessary to use roller shading blinds throughout the summer. These help protect the plants from the sun’s rays, but it would have looked much more idyllic if the sunlight had shone through a small tree.

When it comes to heat it cannot be emphasised enough that ventilation is truly important. As mentioned before you will be surprised of how hot it gets in a glass house. It is not unusual for the temperature to reach 50 degrees Celsius which of course is not healthy for a plant. The plants will get heat damages, flowers will wither away before you can enjoy them, and the water bill will get out of hand. My advice is: air, air and more air. All greenhouse windows and doors should be wide open 24/7 during the summer months.

Ventilation works best when the wind moves the air. But even though we have lots of wind here in Tversted, in the northern Denmark, we also have summer days with no wind at all… and what do you do then? A wise lady once told me that you can lower the temperature drastically by watering the floor in the greenhouse. It sounds strange, but it certainly works! By pouring cold water on the stone floor the water will then evaporate and lower the temperature. It also protects the plants from the sun’s scorching rays.

Species diversity in the greenhouse

Something that many experiences is pests in the greenhouse. Plants that are stressed out are likely to get pests, which can be extremely annoying and hard to get rid of. We got a lot of lice and larvae. It was only two types of plants that got infested even though we had a great number of these harming creatures.

The trick might be to have a wide range of different plants. That way you confuse the pests and at the same time you create better living conditions for the useful animals.

So what have we learned from 2021? 

- Less is more when it comes to the number of plants inside the greenhouse. By planting bushes and trees next to the greenhouse you get a nice view to some greenery and create a feeling of intimacy. If it must be placed inside, we have found it useful to raise up the plants by having shelves, hanging flowerpots and trellises.

- Have a diverse selection of plants. The more different types of plants, the smaller may the risk be of getting pests.

- We love tomatoes but four large plants are more than enough for two. We cannot keep up anymore with the many tomatoes being ready for harvesting. Although you could preserve them or give them to family and friends. 

- You will need the sun and warm temperatures, but during summer it is important to provide shade and air. We have no large trees in the garden so the roller shading blinds is a ‘must have’ for us.