Polytunnels are one of the best ways to boost crop growing on your plot. Whether you are a self sufficient homesteader or simply love growing vegetables, polytunnels can seriously boost your production.
As romantic as the seasons are it takes time for higher levels of the suns UV light to warm up the hemisphere in springtime. Polytunnels provide shelter from frosts and cold winds which can kill off young plants early in the growing season. These undercover growing spaces can also trap the suns heat energy and warm up quickly.
This can inject early life into seedlings and young plants even in the late stages of winter. They enable you get vegetables more robust earlier and permits you to extend your seasonal operations. This is especially useful for crops like squash that need a longer summer season to fruit well.
Polytunnels also give you the advantage of growing more exotic crops during the summer time. This includes tropical crops like peppers, Egg plant and sweet potatoes. Similarly these greenhouses can also provide the perfect conditions to grow cool, climate crops during winter.
This scenario is perfect for boosting winter greens and spring salad leaves. Generally speaking polytunnels have greater volumes of soil than greenhouses which conventionally use more pot grown methods. This enables you to maximise your production and provide a more stable growing atmosphere.
Hence have put together a list of the top 32 crops for polytunnels whether its summer, or winter, below.
Best summer crops for polytunnels
Tomatoes are probably one of the most versatile crops to grow and utilised in all types of culinary pursuits. From salads to chutneys to stews and curries so investing some space for this fruit in your greenhouse is a wise choice. I generally find these are good to intercrop with basil during the summer months. This way you can get two crops in one growing area.
Not everyone loves spicy food but chillies actually have so much more going for them than just extreme heat. I find some of the more mild varieties are excellent for pickling and add some warmth during those long winter days. I find these crops better with some root restriction so if you have a large root run perhaps grow in large, sunken, vessels. Chillies are one of the best crops for polytunnels as they love it warm!
Very much the same plant as chillies but larger and without the heat, peppers are tasty and versatile. I find these quite intensive and need a good amount of sun and rich soil to crop well. I have found they need just that bit of extra heat to do well so defiantly one for a polytunnel or greenhouse.
Cucumbers / Gherkins
These crops are really a tropical fruit and need a greenhouse to thrive but it depends where you live. I have found with a large root run and extensive humidity they just go crazy! If you have a sizable growing space and a long season the cropping can become very overwhelming. Expect to do allot of pickling if you grow many of these.
Aubergine / Eggplant
Another tropical crop perfect for growing under cover is the Aubergine or Eggplant. I have had the best results with these grown over two seasons! Young plants can be overwintered on windowsills for better fruiting in their second season. Warmer climates have better results with these as they need strong sunlight.
These are a real treat and can really be the crown jewels of polytunnel harvests to boast about. I have had mixed results with these and find you need a bit of seasonal luck with the weather. Even in a polytunnel I recommend good light and make sure you get pollinators into the tunnel. Watermelons are even trickier in cooler climates so give them as much love and fuss as possible.
Ginger is another real treat for the senses and can grow really well in a greenhouse or polytunnel. It needs a rich, deep soil and be prepared to start rhizomes off in early spring on a windowsill. Ginger has a bamboo, grass like growing habit but don’t let other crops shade it out too much!
Lemongrass is an absolute staple of Southeast Asian cooking and famous for its role in creating aromatic dishes. This crop is extremely fragrant and surprisingly hardy! I have managed to keep it alive all winter long inside my polytunnel. Consequently during the warm summer months it makes a perfect patio plant.
Although many will say this is a cool weather crop I sow mine in the shady part of my tunnel during the spring. I find it grows much better during this early part of the season and great as a filler crop between larger crops. For a continuous supply you will need to sow in succession.
Basil is often thought of as a Mediterranean herb due to its popularity in Italian cooking. It is however from the tropics and will rarely do well outside so much better in the polytunnel. Very much like coriander Basil is the perfect filler crop and does well with tomatoes. Try more resilient varieties than the typical sweet basil. I prefer ‘British Basil’ which has a darker colour, hardier and smells amazing!
Figs are a real treat and can add that little bit of the Middle East to your garden. Although these are extremely cold hardy they do like warm, sunny conditions to do well. If you are really keen on fruiting these, the polytunnel can provide the perfect conditions. They do need some root restriction to fruit well so I plant them in large pots and move them to a warm wall in summer.
These are much easier to grow in cooler climates than some think and are a very attractive vine. This crop is perfect for the polytunnel and can be given a structure to climb over. Just provide a well worked, deep soil for them to develop large tubers and keep them moist in hot conditions.
Pomegranates are another surprisingly hardy plant but really need heat and sunlight to do well. Very much like figs this can spend most of the year inside the polytunnel in a generous pot. This allows plants to get going in spring, set fruit and then be moved to the patio in midsummer.
Passion fruit is a very beautiful vine with very striking flowers in early summer. Some varieties are actually very hardy and I have seen them fruiting on south facing walls in London. I have also seen them grown and fruited very successfully in cold climates in polytunnels. This is certainly one to try if you like to experiment with exotic varieties.
Runner beans are not always a crop many people associate with polytunnels but can benefit hugely from them. Firstly these do originate from Central America so like it hot so can give you a long season inside a tunnel. They are also perennial in their native range so with some protection can last a few seasons in a warm tunnel. Alternatively you can attempt to do this in large containers and take them in for the winter months.
Lemons and Citrus in general are hardier than many people think! Although these small trees prefer hot, sunny conditions to fruit they are remarkably tolerant in temperate climates. To give you the best chance of fruiting grow them in a sizable pot in a polytunnel. These can come out against a sunny wall during the summer months.
Why not check out my video on how I grow lemons in cooler climates
Grapevines are very cold hardy but in order to fruit well need a long season and lots of sun. A typical problem with these in cooler climates is late frosts or cold, spring winds. These can burn off flowers and young shoots leading to zero fruit. Therefore training a branch of a vine into a greenhouse can ensure a long, undisturbed, growing season. Alternatively you can grow vines in large pots and take them inside the tunnel for the winter.
Winter squashes include squashes like pumpkins, butternut squash and Turks turban. These do most of their growing during a long growing season. They flower and start setting fruit in midsummer with the fruits ripening in autumn. This means they can be stored and eaten throughout the winter months. I find a polytunnel will provide a much longer season for colder climates to make these even more successful.
Summer squashes include courgettes and marrows which are harvested during mid summer. These are prolific producers and in polytunnels can be fruited both earlier and later into the season. I get mine strong in the polytunnel before planting them out in early summer.
Best winter crops for polytunnels
Lettuce is a crop which is actually possible to grow all year round! if you want to do this well however it its best done inside a polytunnel. In the heat of mid summer lettuce can bolt easily whereas on the shortest days of winter lettuce will pretty much be dormant. However if you concentrate on early and later winter you can achieve very impressive and substantial results!
Chard is an extremely hardy vegetable which can produce well in the middle of winter. During this time however it is in more of a dormant state. A sunny polytunnel will get autumn sowings producing well and boost early spring sowings into tasty micro greens.
Wasabi is more famous as an eye watering ingredient added to Japanese cooking. However this is not an accurate assessment of the real plant. Wasabi is a perennial which loves cool humidity, an environment very much like your polytunnel in winter! It needs damp soil to thrive and I harvest the winter stalks and leaves for crunchy salads.
Watercress is actually very closely related to wasabi and thrives in similar conditions. Polytunnels provide these cut and come again crops the perfect growing environment. Simply buy fresh cuttings from the supermarket and root them in a damp part of the winter polytunnel.
Kale is a classic winter green and perfect for planting in summer to ensure a winter crop. However in the polytunnel kale can be sown in autumn and grown into young, bushy plants for the winter. This enables a very early spring crop of leafy greens before much else is growing.
Cabbage is a classic vegetable known and loved across the globe. However this crop is also loved by numerous pests including slugs, snails and the cabbage caterpillar. Growing this crop throughout the winter can mitigate this threat and provide greens in the depths of the dormant season.
Spinach is a leafy green packed with essential nutrients and minerals, it is also very versatile! Young leaves can be used in salads while larger leaves are good in pies and stews. This vegetable loves cool conditions and will grow extremely well in the winter polytunnel.
Spring onions and alliums in general are not commonly associated with greenhouses, quite the opposite actually! However if you are in the business of producing crops in the dead of winter spring onions are a great bet. I generally grow these as bunching perennials and if planted in the polytunnel will feed you even in January.
Rocket is one of my favourite quick salad crops with its peppery taste and quick growing nature. It is this habit which makes it perfect for autumn and late spring sowing in the polytunnel. These can be used to out compete cool weather weeds and create an edible groundcover in winter.
Radish is a true cool weather crop and one which can bring the vegetable patch into life early. This quick cropping root vegetable can be grown undercover during the winter months using successional sowings. They are particularly quick to crop in both early and late winter.
Broad beans are a very effective bean for making the best of cooler weather. I have seen seedlings germinated in November battered by frost and sub-zero temperatures only to bounce back in spring. With some good timing and continuous sowing broad beans can produce a great crop in wintertime. Especially when you acknowledge the young growing tips are great in salads and stir-fry’s! Their nitrogen fixing properties make them a great, edible, green manure, cover crop.
Potatoes do need a good amount of sunlight to store enough energy to make good tubers. This in many ways does disqualify them as a true winter crop. However a sunny polytunnel with a deep soil can push the extremities of seasonal growing and cropping. This is especially so in late summer where you can just eek out enough sun to lift Christmas day spuds. At the other end of the spectrum expect some very early potatoes in spring if you grow undercover.
Parsley is a fantastic herb but I have to say I have always used it more as a salad green. Us Greeks like to cut this up finely and eat it with grilled meats. It is not often talked about as a winter green but I find it my most productive salad crop at this time. If you sow this in late summer and utilise the autumn warmth it will reward you all winter long in a polytunnel.
Thank you for reading my article on the best crops for polytunnels, was it useful? Did I miss anything? Do you have any specific crops you grow which are perfect for growing in polytunnels?
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