One of the delights of greenhouse gardening, is that as well as beautiful flowers and bountiful food crops, we can experiment with growing more unusual plants, flowers and crops.
With controlled temperatures and moisture levels, we can branch out from our standard salads, veggies and heat loving flowers, to sow crops that might more traditionally be found in more tropical climates.
Here are some ideas and tips for some exciting things to grow in your greenhouse:
1. Vanilla
Vanilla is a climbing orchid that thrives in tropical conditions. So if you keep your greenhouse moist and warm, you can enjoy the challenge of growing vanilla. You’ll need to have some patience, because vanilla plants can take a few years to be productive, but once they’re established, you’ll be able to delight in home-grown vanilla pods to use in your cooking.
Creating a tropical environment means monitoring humidity and temperature, aiming for 18-29 C temperature range and 85% humidity for your vanilla plants.
Vanilla orchids are grown best from cuttings, which can be ordered online if you can’t find a local shop to supply them. The leaves will point towards the bottom of the cutting, place the end in small pot of orchid potting soil, or soil with a fir bark mix, up to the first two leaves. Your vanilla needs a neutral pH, so test your soil before planting. Your vanilla plant will need six hours of daylight per day to thrive. Water using distilled water, and aim for moist but not wet soil. Your watering routine can either involve daily misting, or watering once the top two or three inches of the pot have dried out. While vanilla loves moist environments, it does not thrive in soggy soil. You’ll need to add diluted fertiliser once a week.
Support your vanilla plant so that it can climb, and be ready for two years or more to pass before the plant will grow big enough to produce blooms. When it does, you’ll need to be ready to catch the very short flowering window to hand-pollinate the flowers. Do some research about pollinating vanilla flowers, because it is a delicate process.
Within two months of pollination, your vanilla pods will appear. They take six to nine months to mature, during which time you can continue to care for plant. And, finally, when the pods start to turn yellow at the base, they are ready to harvest.
2. Ginger
Another tropical plant that will add a zing to your cooking, is ginger. But unlike vanilla, ginger is relatively easy to grow in your greenhouse. You can start with a root (technically a rhizome) straight from the supermarket, having chosen one with multiple “eyes” that can turn into shoots. You can soak the root for a couple of hours to remove any chemicals added in the supermarket to prevent growth. You can the cut the root into sections, each with eyes, and let the cuts dry for a couple of days before planting.
To plant the root, place with the eyes facing upwards on a shallow bed of compost, and then cover with 1-2cm of compost, leaving the eyes exposed. Keep well-watered, in a warm shot with partial shade. When shoots have developed, you can repot to a larger container, placing the root a bit deeper but ensuring the shoots are exposed. Keep watering regularly, and make sure temperatures stay warm.
Harvest your ginger roots once the plant stops producing leaves, usually in the late summer. You can also keep some roots in the soil for next year’s crop, and over-winter them indoors.
3. Tomatillos
Tomatillos are a delicious savoury fruit related to the tomato, and native to Mexico. They make delicious sauces and salsas.
To grow them in the UK, plant them in your greenhouse in the late spring and keep in a sunny spot. Tomatillos don’t need to be staked, but do need space to sprawl a little. Plant seeds in spring and when potting on, plant seedlings deeply, so that the buried stem can produce roots.
Tomatillo flowers are bright yellow, and will pollinate from a nearby pair. If kept in a greenhouse all summer, you may need to support pollination by hand. Little green hoods will appear, within which, the green fruit will start to grow. Harvest when the fruit is a bright green and firm, and about the size of a marble.
4. Passionflower
Originating in the tropical rainforests of South America, passionflower are glorious climbers with stunning flowers.
Some varieties will grow outside in the UK, in warm and sheltered spots, but the most beautiful tropical varieties need a greenhouse to flourish.
Make sure you have adequate support for your passionflower to climb, as some varieties can reach up to 5m in length. Plant in sandy, well-drained soil that is alkaline, in small pots. Water carefully, to avoid root rot.
When your passionflower plant starts climbing, train it little and often on your chosen trellis or support. Once it has reached the height you’re aiming for, you can remove shoot tips, to encourage side shoots and bountiful flowers.
Keep an eye out for pests such as aphids an spider mites that could harm your passionflowers as they grow.
5. Wasabi
This delicious root, sometimes known as Japanese horseradish, gives a delightful flavour-kick to your cooking. It will grow well in temperatures of 8-20 C, in cool but humid environments and out of direct sunlight. This means wasabi is a great candidate for the cooler and shadier spots in your patio greenhouse.
Grow wasabi from a propagated root (rhizome) in soil that contains organic matter, is well-drained and kept moist. It is relatively hardy and fast growing, producing flowers in March and April and ready to harvest from April to October. Overwinter inside, or wrap in fleece if left in your greenhouse.
6. Carnivorous plants
If these spicy and tropical options don’t tickle your fancy, maybe you should consider growing carnivorous plants in your greenhouse. These can be visually stunning and of never-ending interest to young people, so can be a great way to engage kids in gardening.
Varieties of carnivorous plants include the famous Venus fly trap, Cobra lily and sun pitcher. Each type will have its own specific needs, but in general, they will thrive in sunny spots in your greenhouse and need moist soil and humid environments.
One of the challenges of planting unusual crops and flowers in your greenhouse will be keeping the environment stable and right for all of them. For example, vanilla orchids need higher temperatures than ginger and wasabi, so may not pair well together. Your best bet may be to decide on the type of climate you intent to create and maintain, and then choose plants to suit it.
Whatever choice you make, there is a huge amount of joy to be had from trying new and unusual plants in your greenhouse. We hope you have found some inspiration and ideas for your next horticultural adventure here!