What to plant in June (and other garden tasks for the month)

Eva Nemeth

June is a good month for British gardens. The garden erupts into a glorious fanfare of colour this month. Herbaceous perennials take centre stage and, from the humble geranium to the showy lupin, the cottage garden plant comes into its own. Some need more cosseting than others, so here is a handful of useful low-maintenance plants that thrive in full sun and will be drought tolerant once established.

June gardens retain the fresh green of spring, yet the best of the herbaceous plants are starting to flower, so the colour levels are at their zenith. Poppies are bursting, roses blooming and the first sweet peas appearing. June is all about keeping up with the accelerating growth, putting in plant supports – and the all-important weeding. It is also traditionally the month for clipping topiary, but if it is too hot or too wet, it is better to delay doing it. This is particularly true of box plants, as trimming them in adverse conditions may make them susceptible to blight. If the conditions are right, it is a job I love doing, using hand shears and clearing up as I go. Other tasks this month include sowing biennials like sweet rocket, honesty, wallflowers and foxgloves. Biennials produce foliage one year and flowers the next so, if you sow them now, they should bloom next spring. Sow them in seed trays or modules and put them in a cold frame or cool, sheltered spot until they have germinated. Leave them outside to grow on, then plant them out in autumn. You can also pot some on and leave them until spring to plant out. It is worth making a note in your diary to sow biennials, as there is so much else going on at this time of year. Gardening is all about planning and looking ahead.

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In June, I’m able to pick flowers continually from the borders to make arrangements for the house, and deadheading blooms that have gone over so that the plants keep flowering. In the vegetable garden, I’m harvesting the first salad leaves, broad beans and strawberries, and there is a beautiful crop of white currants, which I use to make delicious jelly. The fruits are high in pectin so – unlike my famously runny strawberry jam – the jelly sets like a dream. I plant out any remaining courgettes or squash plants this month, and keep on top of my tomatoes in the green-house, pinching out side shoots and tying in the main stems. Occasionally, I will force myself to sit down.

This month's garden tasks

• Hoe borders regularly to keep weeds down
• Prune spring-flowering shrubs
• Plant out half-hardy annuals and summer bedding plants
• Stake tall or floppy plants
• Clip topiary plants
• Deadhead blooms to encourage repeat flowering
• Sow biennials
• Pinch out and tie in tomatoes
• Keep sowing salad leaves and radishes

Read More

A detailed guide to growing sweet peas

Plus some more tips

• The growth of many herbaceous perennials and climbers is vigorous at the moment. They often need a helping hand to prevent them flopping onto neighbouring plants or over the edges of lawns and paths. Putting plant supports in place early means that even the most obvious ones can be hidden by the foliage in just a few weeks. Hollyhocks, delphiniums and dahlias will all benefit from staking to keep them looking their best.
• Many house plants will benefit from being outside during the summer months. Increased light levels will enable them to put on more growth, and summer showers and watering will give the leaves a good clean to remove any household dust. Tender tropical plants will be best kept indoors, and orchids should be kept in shadier parts of the garden. Slowly acclimatise them to outdoor temperatures by bringing them in at night.
• For an early show of colour next spring sow biennials now, including foxgloves, honesty, wallflowers and sweet rocket in seed trays. Once the seedlings are big enough, transfer them to individual pots - allowing them to grow on for planting in autumn.
• As soon as your sweet peas start to flower, keep picking them to encourage more blooms. Keep plants well-watered during hot spells and feed with liquid seaweed every couple of weeks to encourage more growth.
• Deadhead repeat-flowering roses, unless you want decorative hips later. Keep an eye out for black spot and burn - if it is present on your prized roses, prune out infected foliage and disinfect cutting tools afterwards.

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• Prune back buxus (box) topiary. Make sure that you use clean sharp clippers to achieve a neat finish.
• Sow french beans, peas, beetroot, carrots, kohlrabi, endive, lettuce, radishes, runner beans, swedes, turnips and courgettes in batches.
• Some apples may have the "June drop" where the tree drops excess fruit. After this it is worth thinning the tree out if the branches are still overcrowded. Protect soft fruit plants with netting if they are getting a lot of attention from birds.
• Keep pinching off the side shoots of your tomatoes, and keep an eye out for pests such as aphids, whitefly and red spider mite, if you are raising them in the greenhouse. Should you discover an infestation, it is worth checking out biological controls. These are perfectly safe to use and if used correctly they are more effective than traditional chemical controls.
• The cut flower garden is full of colour at this time of year, with so many different flowers to choose from. Fill large vases with foxgloves and peonies to create impactful displays for hallways and console tables. Small vases of sweet peas and scented roses are a must at the bedside.

What to plant for June