May's Top Tips

Premier team

A polytunnel comes into its own in May, with young plants jostling for attention and space. This makes it a busy time for the polytunnel gardener. To help you know what to plant or sow in May and to make the most of your polytunnel, have a read of our hints and tips for the month.

May's Top Tips for Sowing and Growing in a PolytunnelWATER, WATER, WATER. Check pots and growing bags daily, even if you have an automatic irrigation system. Most plants do best if the compost is kept moist at all times.

VENTILATE the polytunnel and DAMP everything down on hot days to maintain the best conditions.

INSTALL supports in the polytunnel for plants such as tomatoes, melons, and cucumbers.

SUPPORT tomatoes with strings or canes, and PINCH OUT sideshoots.

THIN OUT and TIE IN vines so that they don’t touch the polytunnel cover.

PATROL the polytunnel daily, looking out for pests, especially red spider mite.

EAT ripe strawberries!

What seeds to sow in a polytunnel in May

Summer is on the way, but as always, there's no way to guarantee optimal temperatures for your seeds in British climes. So, it's always wise to keep your flowers, vegetables, herbs, or fruits protected by a polytunnel or a small garden cloche.

After your garden equipment is set up, it's time to plant your seeds! For the best results, it'll help to know what type of seeds are ideal to sow in May.

French beans

French beans are easy to grow and make a healthy addition to any dish, when harvested. They're an ideal vegetable to plant or sow in May, as the conditions are favourable at this time of year – and should result in a harvest after just 8 weeks. Sow one bean into a small pot with 5cm deep soil and place it in a sunny spot. Make sure you provide them with regular watering during this germination stage.

Maincrop carrots

Maincrop carrots (the larger, crunchier type of carrot that takes longer to grow than early carrots) are a great vegetable to sow in May. Just as with other root vegetables, it's important to space them apart to give them room to grow. Leave around 5-8cm between each seed if you want larger carrots at harvest time! Typically, your first harvest will be ready about 12-16 weeks after being sowed. The earlier you harvest them, the softer they will be. If you prefer them crunchy, leave them until later in the season to harvest.


Cucumbers are known for their cooling effect in salads, sauces, and even drinks. When you're growing them, however, they require a lot of heat, which is why polytunnels are ideal! The cucumber is a tropical plant, so you'll need to alter the conditions accordingly. Keep the flooring of your polytunnel's pathway wet to increase the humidity. May is the ideal planting month for them because the soil is warmer and cold nights aren't likely.

Flowers to plant in May

Polytunnels aren't just for herbs and vegetables. If you want to have picture-perfect florals to put on display, try planting them in your polytunnel. Once your plants have grown and become hardier, you could then move them outside to adorn your garden.

Some ideal flower bulbs and seeds to plant in May include:

  1. Delphiniums
  2. Cornflowers
  3. Sunflowers

How to maintain your polytunnel garden in May

1. Keep your polytunnel ventilated
Keeping plants warm is one of the main attractions of a polytunnel, but there is a limit to how hot your plants should be! If you've got quite a large polytunnel, you could be at risk of developing hot spots in the centre, unless you ventilate the structure properly.

Stagnant air increases the disease risk for crops and plants. You can prevent this by opening side vents, roof vents, and doors on warm summer days.

2. Ensure you have anchored it correctly
With the UK climate there's always potential for summer storms, so May is the ideal time to double-check that the anchoring on your polytunnel is securely in place.

Our anchor plates clamp the foundation tube of each hoop in a 16-inch hole, which has earth compacted on top. Anchoring is essential to prevent your polytunnel from either lifting in high winds or sinking in torrential rain.

3. Increase your watering frequency
As the warmer weather kicks into gear for summer, one of our top May gardening tips is to start giving your polytunnel plants more water. They go through more water when temperatures are warm and need replenishing more often as a result.

You might want to give special attention to plants with larger leaves, as these are likely to lose more water and require more nutrients to thrive.

Pot-bound plants also tend to dry out quicker than those growing freely. This is because the roots are restricted as to where they can grow. Bear this in mind when you are watering your plants. Of course, a more efficient solution might be a polytunnel irrigation system, which can even be connected to a tap timer.

4. Protect your crops with netting
As we get closer to summer, garden bugs are starting to come out in full force. Many birds are also on the hunt for nutrients, so be on your guard to make sure that your plants don't become nature's next snack! Protect any crops you plant this May with polytunnel netting, and double-check that the plants you buy for your polytunnel are bug-free and disease-free before you place them.

We can help with polytunnel gardening all year-round

Here at Premier Polytunnels, we have been helping gardeners of all experience levels grow thriving, healthy gardens for over 35 years. So, if you need help guaranteeing that you get the best crops at harvest time, just let us know!

If you would like to ensure your plants and crops have better growing conditions this year, just browse our high-quality polytunnels online. We know that figuring out what equipment you need isn't always straightforward, so feel free to give us a call on 01282 811250 or drop us an email. You can even request a call back at a time that suits you. One of our friendly team will be happy to help!