A year-round productive vegetable UK garden from February is possible if you know when to start growing vegetables in a polytunnel. Perhaps the most significant advantage in polytunnel farming is that you can start growing from the beginning of the year until the last month. If you’re using a heated polytunnel, it’s even possible to grow vegetables amidst all seasons.
More than knowing when to start growing vegetables in a polytunnel, you must consider the seasons and classify plants into hardy, cold-season, and warm-season crops. Learning about the planting zones in your county will also work to your advantage because it lets you know what plants will survive. To give you a general idea, those rated zone 1a have extreme annual temperatures of -60 to -55°F, while zone 13b is 65 to 70°F.
How To Know When To Start Growing Vegetables In A Polytunnel
You can start growing vegetables in a polytunnel as early as February in locations like Kent because it is suitable for cool-season and warm-season plants. The range of locations is essential because you will know when to start growing vegetables in your UK area if you know your planting zone and expected conditions. And since you’ll be using a polytunnel, you can adjust the indoor conditions accordingly.
Winter gardening is risky even in a polytunnel, but you can still start hardy, frost-tolerant crops in December or January. Some gardeners in Aberdeenshire also mentioned some vegetables could withstand a heavy frost. Common hardy plants for cold temperatures are beets, spinach, leeks, kale, turnips, carrots, radishes, Brussels sprouts, and Swiss chard.
You can harden frost-tolerant crops by gradually introducing them to outdoor conditions and then begin to transplant in February or March. Bulb onions are even hardy enough for January transplanting. There are also semi-hardy vegetables that are ideal for cool-season planting in the polytunnel.
You can grow broccoli, cauliflower, cabbage, and lettuce at the beginning of March in the polytunnel. Parsley and celery can also withstand light frost. These vegetables are best hardened off and transplanted in April.
Suppose you’re in a temperate region of the UK. In that case, it’s also possible to start a second crop of cool-season vegetables in July and August before transplanting them later in the month and September. The second crop considerations will prepare them for the cooler temperatures in autumn. They will also be ready for harvest at this time through the following early spring.
The warm-season vegetables like tomatoes, squash, eggplant, legumes, peas, cucumbers, peppers, and corn can get busy in the polytunnel in March and April. However, remember that some areas in the UK can experience frost even into spring, so the middle of April or the beginning of May is ideal for these crops. Because warm-season vegetables can’t tolerate cold temperatures, it’s best always to check the polytunnel conditions beforehand.
Know your seasons
Late winter to mid-spring
You can start growing hardy plants in the polytunnel from late winter to early spring. If you have a heated propagator, you can sow some other plants early as well. Additionally, you can sow fast-growing tender vegetables in mid-spring.
Late spring to late-summer
Late spring to early summer is the best time to plant summer vegetables, and then you can harden them after the frost. By mid-summer, you can harvest summer crops and remove spent vegetables like cucumber. You can sow vegetables like lettuce, baby carrots, and salad leaves in the polytunnel for a new harvest by late summer.
By autumn, you can plant some vegetables like parsley and calabrese indoors. Some crops like peas are also best for overwintering. In Stirling, you can plant leafy greens in autumn, and cruciferous vegetables are even suitable for early August planting.
Is Year-Round Polytunnel Planting Possible?
Year-round polytunnel planting is possible because you can control the conditions indoors for your vegetables. In counties like Kent, you can even seed cold-tolerant crops in February without supplemental lighting. Polytunnels also work best to start most plants until you can transplant them outside.
You can then seed warm-season crops and harvest cold-tolerant crops around March or April. May can also be the month of harvest for leafy greens and transplanting the vegetables you started indoors. Still, it’s best to have a cooling system to prevent overheating your warm-season crops from June to July.
August to September is for winter gardening in the UK, while November to January might require supplemental lighting as the day length shortens. Overall, you want your plants to mature by November or December so that you can still harvest slowly through winter. And depending on your UK area, the polytunnel can protect your vegetables against frost in the winter.
The most significant advantage of polytunnel gardening in the UK is that it can be productive year-round. But do you know when to start growing vegetables in a polytunnel? In counties like Kent, it’s possible to sow or plant as early as February.
Upon knowing your planting zone, seasons, and crop classifications, you can plant in the polytunnel regardless of the conditions. You can use the polytunnel to protect against frost or start some vegetables indoors until the outdoor climate is suitable.