June

Written by Helier Bowling

June Greenhouse Growing Guide – Helier Bowling

June brings the start of summer in the garden! Having had some lovely warm weather, the garden is full of growth and if you sowed your hardy annual flower seedlings in the autumn, you’ll be starting to harvest some cut flowers too. It’s changeover time in the greenhouse, moving out the lingering spring-sown flower seedlings into their final growing space outside, planting out your vegetables or potting them on if they’re staying in the greenhouse, and starting to think about sowing biennials. Our June Growing Guide brings all these seasonal jobs together to keep your garden thriving.

June Greenhouse Jobs: Annual Flowers, Tomatoes, Cucumbers & Melons

Annual flowers and Dahlias

Prepare to plant out all your remaining flower seedlings, dahlia tubers, however big or successful they are. Greenhouses get hot in summer and it’s time that these were growing outside. Harden everything off outside for a few days and then plant them out. Reserve your smallest flower seedlings for grouping in large pots. And if there are excess still – it’s time to give them away!

Tomatoes, Cucumbers & Melons

Pot these into large containers or a greenhouse bed. In June, warmth and long days fuel fast growth, and bigger root space ensures stronger crops of tomatoes and cucumbers. Stake them with bamboo canes or string. Keep pinching out the shoots that will grow between the main stem and the side shoots, this will focus your plant’s energy on fruit production rather than foliage.

Aubergines, Peppers & Chillies

Pot these up into bigger pots and pinch out the initial growth shoot. In June’s warm conditions, this encourages bushier aubergine, pepper and chilli plants with more branches, which means more flowers and fruit later in summer.

Courgettes/Squash, Beans, & Sweetcorn

It’s time to harden these off and plant them out, fun fact, this trio is known as the “Three Sisters’ as they can all grow together in the same bed harmoniously. In theory you can use the sweet corn to support climbing beans (probably you are best to use separate staking), the beans fix nitrogen into the soil for the courgette/squash, which in turn provides shading of the soil helping to retain moisture and deter pests. It’s a nice idea isn’t it!

Start sowing Biennials

Yes more seed sowing, and the reason to sow biennials is that you get early flowers next year, earlier even than autumn-sown hardy annuals. Biennials are flowers that need to be sown and grown over two years. You sow them now, plant them out over autumn, they overwinter outside and then they flower in May and June.

Here’s some biennials that you can sow now:

Wallflowers, Foxgloves, Hesperis (Sweet Rocket), Aquilegia, Hollyhocks, Sweet William.

If the temperatures get too hot in the greenhouse, place your seed trays/seedlings outside to germinate and grow in a part shady spot.

June Gardening Tasks: Flower cutting, weeding & staking

Cut flowers

If you are growing flowers to cut then plant your flower seedlings in a cutting garden just for your hardy and half-hardy annuals.

Weeding

Make sure you keep your cutting garden weed free. Weeds can grow quickly at this time of year choking your flower seedlings and providing a home for slugs and snails. Once the flowers really get going there will be no room for weeds!

Feeding and watering

Water seedlings deeply rather than sprinkling, so moisture reaches the roots where growth happens. In June’s heat, shallow watering dries quickly. A fortnightly seaweed feed also boosts resilience against summer stress.

Staking

Make sure you have well staked your growing flower seedlings. If you are growing flowers to cut, it’s important to use a staking method like jute netting to give support to the stems in windy wet weather and to keep stems straight.

Cut your flowers

Annual flowers are known as cut and come again flowers. The more you cut, the more they will continue to grow and flower all summer long. Start practising the habit of cutting a few stems everyday for the house. No two bunches/vases will be alike and your house will be full of flowers!

Sweet peas

Keep watering and picking sweet peas in June. Regular cutting stops seed pods forming, which would signal the plant to stop flowering. Frequent harvesting keeps the display going all summer. If you’re going on holiday, cut all the flowers and you’ll return to a flourish of sweet pea flowers!

Direct sowing

You can also sow direct some last-minute seeds, nasturtiums are the perfect seed for this!

Finally

Pots of flowers on all garden tables is a must! Top choices are pelargoniums, erigeron, sempervivums and echeverias.

About the author

Helier Bowling has taught classes with Alitex on how to grow cut flowers as well as teaching and leading a team of volunteers to sow and grow a 5 star gold award cutting garden for Alitex at RHS Hampton Court Garden Festival in 2022. Following on from this success, Helier enrolled with KLC/West Dean and retrained as a Garden Designer. Working with two design colleagues in 2024 their Garden Makers woodland garden was awarded first prize at Royal Windsor Flower Show, then a Silver Gilt Medal at RHS Hampton Court Garden Festival and this year was awarded a Silver Medal at RHS Chelsea Flower Show for a Balcony Garden.

Where to find out more

Instagram @garden_goddess_uk