Essential tasks for June
Keep your garden looking its best with our guide to essential tasks that need doing in June.
In the Flower garden
Lilies: Potted lilies will be growing quickly now and as their flowers start developing they will need some support. Push several canes into the compost around the edge of the pot, linking them up with string to provide stability. If border lilies are not supported by neighbouring plants, use stakes around these too.
Roses: Sprinkle rose fertiliser around roots to encourage strong growth and a good flower display. Water in if rain does not fall within a couple of weeks or hoe into the soil, taking care not to harm the roots.
Bearded iris: Once irises have finished flowering in June, congested clumps can be lifted, divided and replanted. Reduce the leaf area by half and replant so that the rhizomes rest at the soil surface.
Primulas: Dig up large clumps now and divide into individual plants, each with leaves and roots. Replant into newly prepared soil.
Summer bedding plants: Plant out tender bedding plants once all danger of frost has passed. If they have been grown in the greenhouse, harden off in a cold frame for a few days before planting out. Pots and trays of bedding plants can be placed on the patio during the day, but moved back under cover at night. Give them a boost by watering them in with liquid fertiliser.
Lupins and early perennials: Remember to cut off the old flower stems before they start to set seed. This will tidy the appearance of the plant but as an added bonus may even encourage a second flush of flowers. Also keep a watchful eye out for lupin aphids which should be controlled with an insecticide if necessary.
In the Glasshouse
Cuttings: As soon as cuttings taken earlier in the season have produced a good root system, or plants have outgrown their pots, pot them into a slightly larger pot. Try and use the same compost as they were potted in before. Don't overfill with compost, but leave a gap at the top of the pot that can be watered into. Take cuttings of geraniums, fuchsias, coleus and other houseplants now.
Fuchsias: Many young plants, including fuchsias, benefit from having their shoot tips pinched out to encourage branching. If left, shoots can grow very long and lanky, while pinching out creates bushier plants with more stems that ultimately carry more blooms.
Hippeastrum: Pick off dead flowers and seed-heads, unless you are aiming to save seed for new plants. Let the stem die down naturally, then cut it away neatly at its base.
Feed containerised plants: Most composts only contain sufficient nutrients to feed plants for about four to six weeks after potting up. Potted plants will then benefit from a weekly liquid feed to promote strong growth and generous flowering and fruiting.
Greenhouse shading: Paint greenhouses with a shading paint or put roller blinds or shade netting in place for hot days.
Tomatoes: Tap the blooms on greenhouse tomatoes to improve pollination. There are more tips for growing tomatoes in our guide.
In the Kitchen Garden
Vegetable seedlings: Thin out rows of vegetable seedlings growing from earlier sowings, such as beetroot, lettuce and radish. Final spacings are usually indicated on seed packets. Congested seedlings never reach their full potential, as they distort one another as they grow, resulting in a much smaller crop. Carefully pull out unwanted seedlings, leaving the rest at the desired spacing, then water the row to settle the soil back around the roots of the remaining ones. Crops to sow outside in early June include runner beans, dwarf French beans, kohl rabi, carrots, marrows, cauliflowers, peas, ridge cucumbers, sweet corn, swede, lettuce, endive, squashes and spinach.
Look out for pests: As the weather warms up, and spring moves into summer, the garden becomes a real battleground, with pests attacking flowers, fruits and vegetables as soon as your back is turned. Be on the lookout for the first signs of attack, picking off any pests found. Weigh up the pros and cons of leaving plants to look after themselves and putting up with some damage, or applying regular preventive sprays to stop pests taking hold. For instance, gooseberries are almost always attacked by sawfly caterpillars and a preventive spray will stop leaves being eaten away to their skeletons.
Leeks: A good crop of slightly smaller leeks can be grown by multi-seeding them into modules of compost. Sown in February or March, modules can be planted out in May or June, leaving the leeks to grow in clumps. Space the modules 15cm to 20cm (6in to 8in) in rows 30cm (12in) apart.
Cane fruits: Tie new canes of raspberries and blackberries on to support wires as they grow. Keep them separate from last year's shoots which will flower and fruit this summer.
Bird control: Spread nets over soft fruit bushes, such as currants, and over strawberries growing in rows or in containers. Once blackbirds and other birds find fruits to their taste they will return again and again and will quickly strip plants of unprotected fruit.
Pruning shrubs: Many spring-flowering shrubs can be pruned as soon as their flowers have started to fade. Any shoots that have carried flowers can be cut back, shortening them to shape the shrub and control its size and vigour. Forsythia can grow large and ungainly if left to its own devices, so prune to give the shrub a definite shape and form. This and other shrubs, such as Berberis darwinnii, are sometimes grown as hedges, so can be pruned to give a more formal structure. All the flowering stems of Prunus triloba can be pruned to their woody base, while selective pruning on philadelphus and weigela stops them getting large and woody.
Encouraging buds: Sometimes buds on the stems of apple and pear trees remain dormant and don't develop. This isn't a problem unless you are trying to train the tree into a formal shape and need a shoot to grow from the exact position of the dormant bud. Notching is a technique you can use to try and force it into growth. Use a sharp knife to cut out a small piece of bark just above the bud. Do this during the growing season and the sap flowing along the stem will be directed towards the bud instead of by-passing it, and should encourage the bud to develop into a shoot.