Greetings crop pickers, here's the run down of the current top 12 polytunnel crops. Each of our 'Top of the Crops' have detailed growing guides, working with author and long-time polytunnel gardener, Andy McKee, we have produced a series of guides complete with all the do's and don'ts of growing the most popular crops. Whether you are looking to try growing something new, or just want to improve your existing crops these guides will make sure your polytunnel gardening is a big hit with all the family...


Growing Cucumber

Although there are varieties that can be grown outside in Britain, cucumbers do much better if grown under cover. Your polytunnel will allow you to grow the sprawling plants vertically up a cane or string, and you’ll be surprised at just how many you will get – and for how long. For my own family of four, two plants gives us enough at the beginning and end of the season, and way too many in the middle. Recipe book on standby!

Varieties: ‘Cumlaude’ (F1), ‘Burpless Tasty Green’ (F1), ‘Tamra’. There’s a terrific choice though – in future years you might like to try pickling varieties like Crystal Lemon too.

Sowing: Prepare the soil by forking in a generous amount of manure or fresh compost in early spring. Remember these are going to be tall plants, so think about the shade they will cast. Cucumber seeds are expensive and don’t germinate well without heat, so sow them singly 1cm deep into biodegradable pots of seed compost a couple of weeks before the last frost date for your area; you can look this up online. Water the compost well, then cover the pots with cling film and put them on a warm windowsill during the day, and move it to the airing cupboard at night. A heated propagator is better if you have one, as it keeps conditions ideal without the fuss of moving the pots about.

Once the seeds are up put them in a light, warm place but do not allow the pots to dry out. As soon as daytime temperatures in the tunnel reach 21°C move the seedlings out to a bright area of the polytunnel staging for a few days, covering with garden fleece at night,
to harden off.


Cucumbers are very susceptible to cold damage, so don’t plant them out until the weather has warmed up. When planting the seedlings, mound the soil up by 3-5cm and then gently plant a seedling into the mound, biodegradable pot and all. Mounding the soil up like this helps prevent moulds and mildew attacking the base of the stem. Water around the plants to settle the soil, and protect them with a copper ring for a few weeks if slugs are a problem. Have some horticultural fleece ready to protect the plants if the temperature drops below 10°C; if they are damaged by an unexpected frost it is usually better to start again, as frost-stunted plants never fruit well.

As the plants grow give them an organic liquid feed once a week (or every other watering if you have badly drained soil) until they reach a height of roughly 30cm, and twice a week thereafter. Cucumbers are thirsty plants, so will always need a little extra when you water.

Cucumbers are traditionally grown up a trellis with side-shoots tied out horizontally to let them get as much air and light as possible, but you don’t need to go to so much trouble to get good results. You can grow them perfectly well up a length of strong twine tied to a crop bar or clamp: wrap the stem around it as it grows, tying it on with loose loops of twine at intervals.

As the plants grow they will produce fruiting side-shoots, which can be thinned out as much as you need to to prevent the growth getting too crowded; nip out the growing tips of any shoots
you want to restrict, just after the fifth leaf. When
the plant reaches the top of its support, nip out the
growing tip.

Harvest Check out our Growing Guide

Diseases and pests: Keep an eye out for aphids and spray them off as soon as you see them. Although they are seldom a problem on cucumbers they can introduce cucumber mosaic virus, which will stunt or even kill the plant. Cucumbers can also be affected by mildew, verticillium wilt and red mites.

Harvest: Leaving cucumbers on the vine for too long reduces the total yield, so once fruiting starts have a good look through the foliage every few days to make sure you don’t miss any. When fruiting peaks (in August) you’ll need a strategy for dealing with the glut. Cook with them, pickle them, give them away...or cut them young to avoid drowning in the things!

Recipe: Cucumbers are a huge part of many salad and soup recipes. But are probably pickled, pureed and preserved more than any other vegetable. Plus a slice or two of fresh cucumber in Pimms is the perfect summer drink!

© Andy McKee 2011

Download the First Tunnels Top Of The Crops Guide (PDF 739KB)


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