Polytunnel plans – a longer growing season


It’s become abundantly clear that I am in desperate need of maximum growing space, in particular a polytunnel, if I am to realise all my growing goals for 2019. This year, I’ve managed to achieve more than I’ve done collectively in about five years, with preparing new plots, clearing, sowing, planting and restricting. Of course, it’s all great work and I love being proactive yada yada yada… but I fear I’ve outdone myself already. I’m really stuck for growing space.

About three weeks ago I sat one evening, pen in hand, and scribbled out some rough drawings of my veg patches, filling in the rectangular plots with all the fruit, vegetables and herbs I plan to grow this year. I’d already bought and sown umpteen packets of seeds, and I was keen to figure out what was going where, so I had my crop rotation, companion plants and It soon became apparent that the seedlings currently occupying every corner of my greenhouse, conservatory and windowsills – safe undercover as we wait out the risk of a few last frosts in the coming month – don’t all have a home to go to as yet.

I’ve already grown more than I have space for, even with my brand new no-dig bed. The only solution is that I’m going to have to pull my finger out and get a polytunnel up before early summer.

Polytunnels and Peppers

I have an allocated space for the polytunnel; it’s an overgrown patch that needs levelling before I can put something in situ, just enough to take a tunnel about 10×8. That’s enough space to grow some tender, heat and humidity-loving plants like tomatoes, basil, cucumbers and salad leaves. But crucially, it may also give me a shot at growing and harvesting the romano peppers that are currently germinating in the warmth of my conservatory.


This will be my 12th season of growing my own fruit and vegetables, and in those dozen years, I could count on one hand the number of peppers and chillies (capsicums) I’ve managed to harvest. Peppers are notoriously slow germinators, and need sustained warmth and a long growing season to thrive and fruit. I’ve read that they need anywhere between 21-29˚C at a constant.

So my lack of success with peppers is likely down to conditions – capsicums need a long growing season and our climate here in the UK doesn’t offer the longevity. It then goes that the only real solution is to start by sowing as early as possible under protection, to prolong the growing season as much as possible, and then only “planting out” – effectively by “planting under” the protection of a glass/greenhouse or polytunnel.

Cayenne Peppers

Growing Sweet Potatoes in a Polytunnel

I’ve also always fancied growing sweet potatoes. They’re pretty much a mainstay in vegan cooking, full of fibre and nutrients, and also delicious. Which is the main point, really. Sweet potato slips are readily available to buy in the UK, but conversely, the UK climate is not exactly what we would term “optimum growing conditions” for this heat and humidity-loving plant. They need near enough constant temperatures between 21-26˚C to thrive, so are best suited to growing in a polytunnel, training the sprawling stems upwards to save on space. 

sweet potato vines

You can also cover the soil in permeable black liner or weed suppressant matting to help warm the soil even quicker, and retain moisture levels. Sweet potatoes pretty much grow and harvest like a good old ‘spud’ potato, needing lots of fertile, well-draining soil to thrive underground, where the tubers swell and multiply. It’s only the potato vines that need extra space, and training them in a circular fashion or up a trellis helps to minimise their growing space, especially in a polytunnel. 

But before I even think about getting carried away and ordering more slips, seeds or plants, I’ve got a huge polytunnel patch to prepare. I’m planning a ‘polytunnel prep party’, where I basically invite people round to help me clear, level and prep the site in exchange for food, drink and good company. Even with help, I think that’s enough to keep me more than busy this month!

This post was written in collaboration with Premier Polytunnels.