What to plant in June

Premier team

Your polytunnel sowing and growing guide for the start of summer

June can be the hottest, sunniest and often driest month of the year. Things can get very hot in your polytunnel due to the long daylight hours, so the best times of day to work are often the mornings and evenings. However, with UK weather being what it is, you also have the benefit of being able to work inside on wet days – and trust us when we say there's nothing more tranquil than listening to the summer rain clatter down on your polytunnel while you relax and tend your plants inside.

The first month of summer is a great time for sowing seeds and planting young plants. High air and soil temperatures can help get your new projects off to a great start, but you also need to be wary of dry conditions inhibiting growth. That means staying on top of a busier watering schedule.

All in all, June is a month packed full of opportunity for varied, colourful and tasty growing. Here's a quick guide to some of those opportunities.

Seeds to sow in June

If you've been growing in your polytunnel all year, there's a good chance you won't have much space to sow new crops directly. Instead, you can look to grow new seedlings in module trays, and there are several vegetables to plant in June that will provide quick results.

Pak choi

If you're looking for a fast-moving and delicious addition to your polytunnel this June, pak choi is an easy-to-grow oriental brassica that makes a great addition to salads, stir-fries and plenty more thanks to its succulent crispiness. You'll be able to grow salad leaves in the space of five weeks while growing it to semi-mature or full-sized heads will take eight to ten weeks. If you're doing the latter, bear in mind that pak choi plants tend to flower during the summer.

Pak choi is best grown in consecutive small batches so you can benefit from regular harvests. Find out exactly how to grow pak choi from seed with our guide.

Spring onions

Spring onions are a wonderfully versatile vegetable that play a key role in many a favourite recipe. Part of the allium family which includes garlic, leeks and chives, spring onions are a good seed to plant in June because you can typically harvest them in just eight weeks.


If you do have space to sow seeds directly in your tunnel, fennel is a plant used to enhance the flavours of many dishes – particularly fish ones. Fennel needs to be kept warm in the initial phases – around 15-20°C – until germinated. You can expect to harvest by September if you start growing in summer, making it another quick mover for your summer polytunnel growing.

Flowers to plant in June

While it's potentially a touch early, you can start thinking about next year's spring flowers this summer. There are also several classic year-round flowers you can plant in June, as well as spring-to-summer bridge options that will colour next year.

Some of the best flower seeds to sow in June are:

·       Canterbury bells

·       Delphiniums

·       Forget-me-nots

·       Foxgloves

·       Marigolds

·       Sunflowers

·       Calendula

How to maintain your polytunnel garden in June

Up your watering schedule

June represents the official start of summer – and when conditions reach their hottest, sunniest and driest. You may need to increase your watering efforts to stop dry conditions from becoming the scourge of your crops, and also regularly check the soil to ensure you've got a good level of moisture. You can also use mulch (hay and grass cuttings, for example) to help keep your soil moist.

Don't be overzealous with your watering, though. One thing to be very careful of in the hotter months is overwatering and waterlogging your soil, which can be just as damaging to your crops as drought.

Ventilate to keep things cool

It can get very hot in a polytunnel in the peak sunshine months, which is why we recommend working in yours at the bookends of the day to avoid some uncomfortable conditions under the polythene cover. Keep yourself and your crops happy by ventilating the space as best you can, opening the doors and side vents of the tunnel to provide vital air circulation.

Introduce some shade

In further efforts to keep temperatures down as sunlight exposure increases, you'll want to give your crops some shade where possible. Our net polytunnel cover provides 47% shade from the midday sun whether you've got a polythene cover in place or not.

Polytunnel Growing Guide for JuneUsed on its own, a net cover provides shade, full ventilation, a significant reduction in wind speeds, and still allows rainwater to filter through to the plants. Placed over a polytunnel with a polythene cover in place, the net provides shade and significantly reduces the temperature inside.

Alternatively, you can add some shade and reduce temperatures by tying shade net above head height on the inside of the polytunnel. Use cable ties to secure the net to the polytunnel hoops, ridge bars, or crop bars. 

Keep things in check while you're on holiday

If you're off on your summer holiday in June, there's no need to worry about bothering your friend, neighbour or family member to water the plants that you've carefully tended and nurtured.

Our Premier Irrigation Kits (available for all sizes of polytunnels) include a top-of-the-range Galcon battery-operated tap timer, doing away with the need for someone to do the watering. That means that you can go on holiday safe in the knowledge that your crops will still regularly get the water they need.

Look after yourself!

While it's crucial to look after your polytunnel garden at this rather warm time of year, don't forget about yourself! You can still get a suntan (or worse!) while working inside a polytunnel that's covered with a standard or Thermal Anti Drip polythene cover, so don’t forget the sun cream!

Let us help you grow in your polytunnel all year

With over 35 years' experience in the industry, helping everyone from green beginners to seasoned professionals make the most of their gardens, you can trust us to help you maximise your harvest every single season.

Our top-quality polytunnels provide a healthy environment for growth throughout the year, and we know exactly what it takes to help all our customers realise their growing ambitions.

Have a question? We'd be happy to help. Give us a call or send us an email today and one of our dedicated team will get back to you with everything you need.