Seasonal Garden Tips
JULY
• Earth up potatoes, to stop the tubers near the surface becoming green. Where blight is a problem, spray them with Bordeaux mixture.
• Dead-head herbaceous plants such as delphiniums and paeonies to keep them tidy, and those such as petunias and nasturtiums to keep them flowering longer.
• Keep edges well trimmed, and cut back with an edging iron those that have spread.
• Strawberry plants are usually kept for three years, then replaced. Replacements can be started now by pegging down some runners for lining out in September. Set small pots in the soil and peg down into these.
• If the existing plants are in imperfect health, it is better to buy new ones. Continue to plant leeks for successional cropping.
• Stop cucumbers at desired height, and stop fruiting side-growths after the second leaf. Take off male flowers and those on the main stem. Shade in hot weather.
• June-flowering border irises can now be lifted and divided, in about every fourth year. Replant only the fattest rhizomes, at surface level, 9 in. apart.
• Give away or burn the remaining rhizomes, but do not compost them.
• Most hedges can be given a light trim now to keep them looking tidy. Slower growing hedges like box and yew can be left a little longer and given a once-a-year cut.
• Begin shortening side shoots on plums. Pears and apples may be summer-pruned now too, shortening back lateral growth to allow the sun in to the fruit.
• Water courgettes, tomatoes, celery, sweetcorn and cauliflowers.
• Earth up brussels sprouts. Stake outdoor tomatoes and remove side shoots.
• Remember not to stop the tops of bush tomatoes.
• Give liquid feed fortnightly to cucumbers and courgettes.
• Now is the time to plant or divide autumn-flowering bulbs such as nerines, colchicums and sternbergia. Colchicums are easily grown in grass, like daffodils, and increase very readily into large clumps.
• Water lawns as necessary. Lawns sown or turfed this spring will now be strong enough to be treated with selective hormone weed-killers, when not too dry.
• Regal pelargoniums will finish flowering this month, and can be kept fairly dry, and rested for a few weeks.
• Sow spring cabbage and winter spinach in the ground. Line out young plants of winter and savoy cabbages.
• Take cuttings of pinks, to replace plants 3 years old. Shoots 3 in. long root easily in shaded soil or a pot. Pinch out the centre when they begin to grow.
• After flowering, mature Philadelphus and Deutzia bushes should be pruned.
• Take out dead and crossing wood, and remove 50% of the long shoots that flowered this year. This year's new shoots will flower next year.
AUGUST
• Continue to earth up potatoes, celery and leeks, for long stems and white tubers.
• Plant Madonna lilies now, since they will put on leaves in the autumn.
• Plant leucojums too and, in a really sunny corner, the tender Amaryllis belladonna.
• Cut areas of wildflower grass now, when flower seeds have ripened and dropped.
• Rake off all the grass and compost it. Mow again as necessary to keep it tidy. Introduce seed or small plants now, while grass is weakest.
• If necessary Spray against blackspot and remove suckers on grafted roses, where they meet the rootstock.
• For holidays of up to a week, soak houseplants and move to shady north window sills, or ask your neighbour to water your plants.
• Keep hoeing between vegetables to keep weeds to a minimum.
• A sowing of onion seed to provide plants for spring planting should be made now in a sheltered nursery bed.
• At this dry time of year, water established perennials to keep them blooming. Border phlox are extremely thirsty, but will go on from July to September with enough water.
• New lawns can be sown now, on well-prepared soil. If dry, soak periodically, but do not keep the surface permanently wet or you risk disease/damping off.
• Take semi-ripe cuttings of rosemary, lavender, weigela, buddleia, santolina and escallonia, remove lower leaves and dip in rooting hormone. Root in 50% peat/sand. Pot on into small pots when rooted, and overwinter in a frame.
• As the first spring bulbs become available, plant bowls and plunge them outdoors for an early display.
• Liquid feed runner beans and water well, to keep them cropping longer. Pick beans regularly.
• As the taller dahlias begin to get top-heavy with the weight of growth and flowers, be ready to supply extra support, especially in wet weather. Dead-head as necessary. For extra-large flowers, remove side buds from central blooms as they begin to develop.
• To encourage dense, bushy plants, lavender should be clipped over as the flowers fade. Aim to shorten new shoots but not cut into old wood. Try to keep the sides of the plants bushy too.
• Continue to trim hedges of privet, beech and lonicera. Yew and holly may be given their once-only cut at the end of the month or in early September.
• Stop outdoor tomatoes (not bush types) after the fourth truss of flowers.
• Dry off the first onions.
• Michaelmas daisies intended for cutting should be thinned now, to give just a few good stems per plant.
• Plant bulbs of the crown imperial fritillary together with a short marker cane to save them from the hoe in spring.
• Keep dead heading bedding plants to produce more flowers. Summer tip-cuttings should be hardened off if taken under polythene, and potted up individually, as soon as they are rooted. Use only small pots, 2-3 in. across. Continue to trim hedges of privet, beech and lonicera.
SEPTEMBER
• Gather French and runner beans regularly and never leave any pods on the plants to become old and stringy unless they are required for seed purposes.
• Spring bulbs can be planted in the garden now, with the exception of tulips. On average, plant bulbs at twice their own depth.
• Prune out the flowered canes of loganberries and tie up the new ones, evenly spaced out. As the season ends, this again is a good time to move or plant evergreens.
• Soak 24 hours beforehand, and water well after planting. Choose a dull day.
• Water Christmas cacti after their summer rest. Bring in houseplants from the garden before the frosts.
• Begin to lift and store potatoes. Maincrop carrots and beetroot should also be stored, or the roots will become woody and crack.
• If your garden is short of colour, notice how many perennials can be at their best this month, e.g.. Anemone japonica, Sedum 'Autumn Joy' and Rudbeckia 'Goldsturm'.
• Buy and plant new strawberries to replace poor or diseased stock. Keep them well watered. This is the time to relieve any effects of summer wear on the lawn.
• Spike particularly any areas of great compaction, and scarify if necessary.
• Put in plants of spring cabbage, to establish before the winter: also any late winter cabbages, savoys, and kale.
• Cuttings can be taken now, from vigorous shrub and climbing roses, to provide sucker-free plants.
• Hybrid tea roses are less successful. Give plenty of ventilation in the greenhouse during the day and, when possible, at night, to prevent fungal disease.
• Pot narcissi, hyacinths, crocus and snowdrops for spring display, and plunge the pots in a shady cold frame.
• Pick remaining tomatoes and lay them out to ripen in a warm place out of direct sun. Sunshine will simply shrivel the fruit, not ripen it.
• Sow cauliflower for early summer use, and overwinter them in the ground under cloches or in pots in a frame. Watch out for slugs.
• Take cuttings (side shoots) in a cold frame of perennial wallflowers, pansies and penstemons. These can be planted out next spring.
• Watch out for aphids on cuttings. Pick early pears.
• On fan-trained peaches, nectarines and Morello cherries, cut out flowered shoots and tie in replacement shoots to fill the spaces evenly.
• Lawn weeding should be done by hand. Firm the soil again afterwards
• Yew and holly may be given their once-only cut at the end of the month or in early September. Begin to cut out the flowered canes of early ramblers, and tie in the new shoots.