Gardening in June

Roses can produce unsightly ‘suckers’ – vigorous, ugly shoots which rise from the roots. These stand out as they’re often pale-leaved and lighter in colour than the dark, glossy foliage of the rose itself. It’s tempting to grab the secateurs and chop suckers off, but this actually encourages more to grow. Instead, carefully dig down to expose where the sucker is emerging from, then twist and pull it away with a gloved hand.

Throughout June, lilies are growing fast and flower buds are swelling. Keep a lookout for bright red lily beetles which can decimate plants if left unchecked. These pests, which have run riot across the UK since the 1990s, are easy to spot, as adults have bright scarlet shells. There are other tell-tale signs of lily beetle trouble: sausage-shaped eggs on the underside of leaves and red-brown larvae, which are often hidden in sticky black excrement. Adult beetles should be removed and squashed on sight, while larvae can be controlled with a spray of bug killer.

Develop a routine of dead-heading several times a week. Sweet peas run out of steam quickly if spent flowers are left to go to seed, so remove faded blooms promptly – or cut their wonderfully scented flowers for the vase – and more will follow. Roses will thank you for regular dead-heading, too, by repeat flowering into autumn. Remember to dead-head Oriental poppies after flowering, while foliage can be chopped down to ground level; a proven way of encouraging fresh growth of leaves and possibly more flowers.

Nothing beats the taste of home-grown spuds, and first-early potatoes should be ready to lift in June and July (about 10 weeks after planting).

But how do you tell when your crop is ready? Traditionally, gardeners were taught to wait until flowers open or buds drop, but there is a cheat. Carefully draw back soil with your fingers until young spuds are visible. If tubers are the size of a hen’s egg or bigger, they’re ready to harvest. Take the biggest to eat now, and leave the remainder in the ground to carry on growing.

June is a perfect time to sow biennials – plants that develop foliage and roots in their first year and flower in their second year, such as foxgloves and sweet William.

• Prepare a seedbed (a spare bit of veg patch or flower bed will do) by digging the soil and raking it to a fine tilth. 
• Sow biennial flowers thinly in shallow drills and keep the area well-watered. 
• Once seedlings are up, thin them out to prevent overcrowding, and avoid damage by putting down organic slug pellets. 
• In early autumn, plants can be transplanted into their final flowering positions.

Once flowering is over and leaves have died down, it’s time to dig up tulip and hyacinth bulbs. Neither like being left in garden soil over summer, where dormant bulbs are prone to rotting or pest invasion in damp conditions. Instead, store bulbs in shallow trays in a cool, dark garage or shed over summer. Other spring-flowering bulbs, such as daffodils and bluebells, can remain in the ground.

There are tricks that can save you time and money when watering while ensuring that plants benefit most. To avoid water loss due to evaporation, water first thing in the morning or just before dusk, when temperatures are lower. Don’t drench entire flower beds. Instead, direct water at the base of the plant, allowing it to soak into the soil before repeating. Avoid spraying foliage when it’s in direct sunlight, or you risk scorching the leaves. Hanging baskets may need to be watered twice daily during hot spells. Don’t water established lawns though, because parched grass will recover when autumn rain arrives.

Would you like big, juicy fruit in autumn, or a tree laden with tiddlers? For most of us, it’s a no-brainer, and that’s why it pays to remove excess fruit from trees so the remaining crop improves in size and quality. Many trees naturally drop small fruits in early summer (known as June drop), but further thinning may be necessary on apples, pears and plums. Thinning also allows sunlight to reach the fruit, helping it to ripen evenly. Thin dessert apples to one or two fruits every 10-15cm and pears to two fruits every 10-15cm. With plums, leave one fruit every 5-8cm. Keep fruit trees well-watered during dry spells.

Keeping coldwater fish is a fascinating hobby, so stock up your pond now. Sit the bag containing fish at a shady edge of the pond for an hour, so the water in the bag gradually equals the temperature of the pond. Carefully open the bag but don’t pour the fish out; instead, allow them to swim out in their own time. It’s normal for new fish to hide for the first week, so don’t be alarmed if they disappear. If blanket weed is a problem, remove it by dipping a cane into the water and ‘twirling’ the weed around it. Leave the weed by the side of the pond, allowing time for wildlife to crawl back into the water. Top-up ponds if necessary using rainwater from water butts; chlorinated tap water may upset the balance of a pond.

In mid-summer, our gardens produce a lot of waste, much of it comprising grass clippings. You may not think anything of piling the compost bin high with grass, but a bin filled with a good mixture of garden waste will help the contents rot down faster. For best results, mix grass clippings with spent plant stems, shredded paper, vegetable waste from the kitchen and prunings. Don’t allow compost bins to dry out in hot weather – keep the contents moist but not saturated. To speed-up composting, use a garden fork to regularly turn the compost heap. And when adding grass clippings, mix in a spadeful of garden soil, too.

More on how to compost properly >

Lupins are a staple of traditional British flower borders, producing a kaleidoscope of colours that are renowned for their ability to attract bees in their droves – perfect for gardeners who are increasingly seeking out plants that lend a helping hand to struggling pollinators.

The enduring popularity of lupins lies in their ability to add height and drama to the middle and rear of borders. They’ll grow happily in sun or part-shade and won’t complain if the soil is only moderately fertile, although it must be well-drained. Lupins can be grown individually but provide maximum wow factor when planted in large clumps or drifts. However, they’re not recommended for containers, because the plants are best suited to garden soil and will become stronger when allowed to get their roots down into the ground.

To avoid displays fizzling out before the end of June, regular deadheading is a must. Flowers left in situ after they have gone over will quickly bear fat seed pods and that’s game over for this year, but use secateurs to remove spent spikes and the second flush of flowers can follow.

Gardeners must be vigilant for pest attacks. Slugs and snails think that Christmas has come early when tender shoots of lupins emerge, so deploy organic slug pellets at the first sign of trouble, or sink beer traps into the soil close to lupins, to lure molluscs to a drunken end. As plants develop, the biggest threat comes from aphids, which can infest foliage at breakneck speed, weakening plants and causing leaves and stems to collapse. Either chemical or organic bug sprays will quickly control the problem but don’t delay, because a build-up of aphids can rapidly wreck your efforts and spread to neighbouring plants.

Modern varieties of runner beans yield harvests of succulent, stringless pods that are rich in vitamin C, iron, folic acid and fibre, cropping well even in poor summers. Runners are highly ornamental, too, flowering in shades of red or white, making these vigorous climbers a valuable addition to flower borders, whether grown-up bamboo cane wigwams or obelisks – so even gardeners who don’t have a veg patch can enjoy a tasty crop.

Runner bean ‘Firestorm’ is one of the best British-bred newcomers; a red-flowering marvel that’s famed for wonderfully sweet and tender stringless pods that set even in high temperatures or if summer is a washout. Another winner that thrives in poor weather is ‘Moonlight’, a white-flowering type that bears long, stringless pods with excellent flavour. Feeling competitive? ‘Enorma’ produces exhibition-quality beans that combine flavour with pods that are worthy of prizes at horticultural shows. If you only have a balcony or patio, try ‘Hestia’, a novelty dwarf runner bean for pots with red-and-white bicolour flowers followed by long, stringless, flavoursome pods.

To sow directly outdoors:

• Choose a sunny site with deep, moisture-retentive, well-drained, fertile soil. 
• Sow seeds 30cm apart, covering each seed with 5cm of soil, then firm down gently and water. 
• To avoid gluts of beans, sow limited numbers of seeds in succession until the end of June. 
• Plants will need canes for support as they climb, and soil must be kept moist and weed-free.

Watch out for slugs and snails, which are partial to young shoots. Black bean aphids can be a nuisance too: reduce the risk of infestations by removing the growing points of beans when they reach the tops of canes, and spray with an organic insecticide if necessary. Beans are at their most succulent (and stringless) when young, so pick before pods become lumpy with swelling seeds – regular runner bean harvesting will encourage plants to carry on cropping from August into early autumn.

There’s no better way to create a jungle-like chill-out zone in a shady corner of the garden where little else will grow than by introducing an Australian tree fern. Large, arching, divided fronds unfurl from slow-growing trunks, adding an exotic look to any sheltered spot. Tree ferns grow well in containers, too: simply feed with liquid seaweed extract a couple of times during the growing season and protect the crown (centre) with straw in winter.