Welcome the First Tunnels Growing Guide. We know how to make great polytunnels, how to construct polytunnels and tailor a polytunnel to an individuals preference but we’re not gardening experts. Thankfully we work with several of the countries leading polytunnel gardeners, people who have been using our polytunnels for years. Each month this year we will produce a growing guide working closely with Mark Gatter, author of 'How to grow food in your polytunnel'. Mark has years of experience and has kindly offered to share some of the hints and tips he’s picked up over the years
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Still winter, isn’t it? But spring is just around the corner, so there’s lots to do in the polytunnel. If you’re planning your first polytunnel this year, a sunny day in February is a great time to put the cover on in time to get early spring plantings up and running far earlier than you could outside.
Plastic is more flexible when warm, but as long as the sun is out – even if it’s a cold day – as soon as you pull the cover up over the hoops you’ll be amazed how quickly it warms up inside. After just a few minutes, the cover will be flexible enough to tighten down, and you won’t need to re-tighten it later in the year.
If you already have a polytunnel, February is a great month to clean up in preparation for the beginning of the growing season – March! There will be spaces here and there from winter harvesting, and you should fork some compost into all these as soon as possible. Staging and tools, as well as all your seedling pots, should get washed with a solution of warm water and a non-toxic biodegradable soap such as Algon. Clean the cover as well, inside and out, so everything can benefit from the increasing day length.
I always start a few seeds in February just to see what I can get away with. A sunny windowsill, a cold frame and some horticultural fleece cloches all help with early crops. If you live in the north, you may want to consider starting a few seeds indoors under lights, not the ‘greenest’ way forward, but a 200-250W fluorescent light – designed for vegetation will allow you to start loads of veggies in a small space indoors without a costly spike in your electricity bill. And you’ll only need to do this until you can start moving things out to the tunnel in March. Remember that sudden cold can be a serious shock to young plants, so put a cold frame or a fleece cloche or mini polytunnel in the tunnel to house them for the first 2-3 weeks. Once April arrives, it’s unlikely that temperatures inside the tunnel will drop far enough to cause problems.
February is a good time to get set up for the warmer weather so you don’t get caught out when it arrives. An automatic watering system is a great time-saver once it’s set up, but its timer is something you should thoroughly test before going on holiday!
Regular ventilation is essential, even during the colder months, as mould will spread quickly. While it’s less likely to cause problems in winter it’s still around, and low growth rates and light levels, together with a cold, damp environment, don’t help. However, don’t ever leave the tunnel open overnight in winter. I open the doors for a few hours in the middle of the day, whenever it’s not too cold outside and especially if it’s sunny, but if it’s overcast and seriously cold I leave them closed. Once the weather warms, try to open the doors as soon as possible in the morning and close them again about half an hour before the sun stops hitting the tunnel. That way you’ll get plenty of air circulation without losing valuable heat.
Get some ‘first early’ seed potatoes and start ‘chitting’ them - set them out in egg boxes near a bright window so they begin to sprout. When the sprouts are about an inch long, plant the spuds in the tunnel. You’ll be rewarded with the earliest of earlies sometime in the second half of April.
As well as continuing to sow broad beans, garlic/ elephant garlic, peas (round-seed varieties) and turnips you can also start sowing aubergines, peppers, strawberries, sweet potato and tomatoes and anything else on the ‘harvesting’ list below. And yes, I know, you’re thinking ‘Aubergines, peppers and tomatoes in February?’ In a regular vegetable garden this would be a complete waste of time. But not in a polytunnel...
Everything on the ‘harvesting’ list.
Beetroot, cabbage, carrots, cauliflower, celeriac, celery, chard, coriander, daikon, kohlrabi, lettuce (and other salad greens), mizuna, pak choi, radish, rocket, spinach, spring onions, turnips.