June - What To Sow, Grow & Do In The Greenhouse & Yard

The summer is here, and June can be a delightful time in your yard. The flowers and crops you have been tending since early spring are coming into their own, and your yard is heading towards abundance.

By now, you've probably hardened off and planted out much of what filled your greenhouse over the past few months – but that doesn't mean your greenhouse shelves need to stand empty. June is a great season for sowing and transplanting heat-loving crops, getting late-sown salads in the soil and starting your autumn and winter vegetables.

Our friends and experts Ellen Mary, Gill Meller and Jeska Hearne have provided us with lots of tips and tricks for June, which we've compiled into this guide.

What to Grow in June: At a Glance

Use this table as a quick reference for what to sow and plant in June. Each crop is covered in more detail in the sections below.

Heat-Loving Crops to Sow in Your Greenhouse in June

Tomatoes

It's not too late to sow tomatoes in your greenhouse. You may well have already tended your seedlings, hardened them off and planted them out – but getting another round of seeds in the soil now will extend the succulent tomato season and fill your plates into the autumn.

Remember that you're planting in warmer conditions, so your watering schedule needs to be regular, and you'll need to prevent overheating and scorching through careful use of ventilation and shade. Some gardeners keep tomatoes in greenhouses all summer rather than planting out, in which case, think about your support structures for the vines as they get larger.

You'll also need to be more actively involved in pollination when your tomato plants bloom, because insects won't always find their way inside. Gently shake the plants when they're flowering to move pollen around, or use a soft brush to transfer pollen between flowers.

Gardening expert Ellen Mary demonstrates this in the video below. She asks, do you tickle your tomatoes?!

Chef and food writer Gill Meller describes the pleasure of the tomato season in his Devon (UK) yard. "It's the only real time I eat tomatoes over the year, so I like to make the most of them when I can," he says. He treats them simply with good olive oil and flaky salt, served with warm crusty bread, basil and burrata. When the really ripe ones pile up, he roasts them with garlic, thyme and olive oil, then passes the blistered fruit through a sieve for a passata that doubles as the base for a roast tomato soup.

Gill has also learned the hard way about blight.

His approach is ruthless vigilance: secateurs drawn at the slightest blemish, anything discolored cut away immediately. "This rather ruthless approach has paid off," he writes, "and despite the damp weather and below average temperatures, I think we're going to get this crop over the finish line."

Peppers and Chilis

Another heat-loving crop to plant in your greenhouse in June is peppers – both sweet and spicy varieties. Seeds planted now will be ready to harvest in autumn. In the heat of a summer greenhouse, certain varieties will thrive, so make sure you choose pepper and chili seeds that really love the warmth. Keep seedlings well-watered and watch out for pests as you tend them through the peak of summer.

Cucumbers

Cucumbers will be plentiful throughout the summer if you sow them in your greenhouse in June. Seeds tend to germinate in 5–10 days, and the seedlings will thrive in a propagator or under cover to retain moisture. As they mature, transplant them into pots in your greenhouse or outside in the veg patch.

Gill Meller discovered the value of training cucumbers vertically, running strings up the sides and across the roof of his greenhouse rather than letting the vines creep along the floor. The result: straighter fruit, better airflow and a crop so prolific he had to give much of it away. He pickles them with cider vinegar and cilantro seed, fries them with garlic and black pepper, and grates them into cool minty raitas. "These cucumbers are completely different to shop-bought," he says. "In fact, they taste like melon."

Herbs

June is a great time to sow basil, cilantro, parsley and other tender herbs, adding wonderful flavors to your summer cooking. Some herbs offer benefits beyond taste: basil makes a great companion crop for tomatoes because it discourages aphids. Your herbs will love the warm, stable conditions of your greenhouse, but they'll rapidly let you know if they're not getting enough water.

Melons

If you're looking for something sweeter, June is a fine time to try growing melons. Cantaloupe and honeydew varieties will thrive in the summer heat and humidity of your greenhouse, doing well in a container or grow bag. With the right care, each plant can produce up to six delicious fruit.

Microgreens

Gardener and author Ellen Mary uses her greenhouse for growing microgreens year-round, and summer is no exception. She sows densely into trays of compost – everything from basil to fenugreek, radish to spinach. Harvested when they're no bigger than 10cm, they're packed with nutrition and add vibrant flavor to summer dishes. "The scent when opening the greenhouse door is delightful," she says.

Autumn and Winter Vegetables to Sow in June

As well as your late-sown summer crops, June is a good time to think ahead to how you want to fill your plate towards the end of the year. Starting these crops now in the greenhouse gives them a head start before the weather turns. For a full list of what to sow in every season, our monthly seed sowing guide covers the year at a glance.

• Leeks: Sow late-cropping varieties now to harvest in winter and early spring. Leeks can be harvested at any size and, as long as they don't bolt, can be left in the ground during cold months – ideal for winter stews and soups.

• Brussels sprouts: It might feel too early to think about Christmas dinner, but June is the ideal time to get Brussels sprout seeds in. They need a long growing season, so starting now means they'll be ready when you need them.

• Kale: Generally a cool-season crop, kale can be sown in June with the right care. Keep it shaded and well-ventilated to prevent bolting during the summer heat, and you'll be harvesting through winter. For more on this powerhouse vegetable, see our piece on kale for Christmas.

• Winter cabbage: June is the perfect time to sow. Pick a late-sowing variety when you choose your seeds.

• Broccoli: Sow seeds this month for a harvest at the end of the year. Keep seedlings well-watered and pest-free.

• Fava beans: Gill Meller has found that sowing fava beans in late autumn for an early start the following year produces far stronger plants than spring sowing. But if you missed that window, our guide to overwintering fava beans is worth bookmarking for later in the year.

June Jobs in the Yard

Planting Out

Risks of frost should now be long behind us, so it's time to plant out annual summer bedding in borders, pots and containers. If you've been growing them in the greenhouse, make sure they're hardened off properly before going into their final positions. Tender vegetables like zucchini, sweetcorn and outdoor tomatoes can go out now too – individual cloches or a layer of row cover fabric can help them adjust.

When planting out brassicas, Ellen Mary recommends using cabbage collars around the base of each stem to prevent cabbage root fly. They also help deter slugs and snails on young plants.

Cut Flowers

Ellen describes her cutting yard coming alive in June. Spring bulbs have faded, making room for towering Allium christophii and Allium siculum that have the bees dizzy. Annuals sown earlier in the season are hardened off and planted out, while sweet peas and directly sown nigella, ammi visnaga and godetia are already growing happily outside.

Her favorite annuals include French marigolds (easy from seed and perfect as companion plants), cosmos for their feathery foliage and colorful blooms, zinnias, sunflowers, cerinthe major, cornflowers and calendula. All are excellent for cutting and easy to collect seed from for the following year.

Pest Watch Outdoors

Keep an eye out for woolly aphid on apple trees, cotoneaster and pyracantha. You'll notice bumpy swellings on bark and aphids covered in white fluff. A spray of soapy water usually does the trick, or brush them off with a stiff brush. Left untreated, the damage can lead to canker. For carrot fly, a barrier of row cover fabric around your carrot patch at 60cm to 1m high will keep them out – they can't fly higher than that, so there's no need to cover the top.

Supporting Wildlife

As the weather warms up, keep bird baths topped up with fresh water daily and continue providing supplementary food. To prevent the spread of disease, clean feeders and baths thoroughly each week. Our guide to bringing wildlife into your yard has more ideas for supporting the creatures that share your plot.

Tips for June Greenhouse Care

We spend so much of the year keeping our greenhouses warm and holding onto precious heat, but now the season of managing high temperatures is upon us. Ellen Mary puts it simply: if ever there was a time to get airflow through your greenhouse, now is it.

Ventilation

As the days get hotter, make sure the airflow to your greenhouse is adequate. On warm days, open your vents and doors to keep air circulating and stop temperatures climbing too high. An automatic louvre system will open and close in line with the weather, keeping ventilation consistent even when you're not around; the Rhino Premium and Ultimate ranges incude auto louvres as standard. For more detail, our guide to keeping your greenhouse cool in summer covers all the options.

Shade

Strategic shade will be important as summer gets into full swing. Take a look at different shading methods, including shading paint, mesh and greenhouse blinds, to help prevent scorching.

Watering

Timing your watering to avoid evaporation is key. Water early in the morning before the heat rises, or in the evening once the sun has passed, so that plants are nourished before moisture evaporates. We recommend considering a irrigation system, which will automatically water your plants for you. Don't overwater, that can cause diseases just as readily as drought.

Tomatoes in particular prefer consistent watering rather than big fluctuations. If you're going on holiday, plan ahead with automatic vents and a connected water butt.

Pest Management

As always, pest management is on the agenda! Summer heat means summer pests, and greenhouses can make all-too-cosy homes for uninvited guests. Keep an eye out for the telltale signs of aphids, whitefly and red spider mite, and act quickly with organic pest control as soon as you notice them settling in. Sticky yellow sheets catch whitefly effectively, and removing any dead or diseased foliage straight away reduces the risk of problems spreading. Our guide to keeping your greenhouse pest-free goes into more detail.

Ellen Mary also recommends watering down the greenhouse floor in the mornings. It raises humidity slightly, which helps with red spider mite, and keeps the environment healthier overall.

Keeping Your Greenhouse in Shape

Summer is a good time to give your greenhouse a clean. Gill Meller describes his approach: a soft-bristled scrub brush with a few drops of dish soap, the hose and a bit of elbow grease. "It usually scrubs up real nice," he says, "as long as there haven't been too many pigeons roosting in the ash trees above."

For a more thorough clean, our guide to cleaning your greenhouse glass covers everything from frame to pane. And don't forget to look after your tools while you're at it.

Enjoying the Summer Yard

June is one of those months where the hard work of earlier in the year really starts to pay off.

Gill Meller captures the feeling well: "Harvesting ingredients you've grown yourself is an incredibly holistic experience and everything always tastes so much better than anything you could buy. Spending an hour or so in the yard helps me slow down and reconnect with nature."

Jeska Hearne, looking back on her first summer of greenhouse growing, sees it as a learning curve she wouldn't trade. "We now know where best to grow taller things, to give our beetroots plenty of room, and to leave the greenhouse open in the daytime for fresh air," she writes. Her advice for fellow beginners: start gently, learn from what goes wrong, and don't be afraid to try again next year.

Ellen Mary puts it simply: "Fill your yard with flowers because they really do make you happy, and when you can take some for an indoor vase, you'll smile every time you pass them by."