Gilnahirk Horticultural and Civic Society
Join. Learn. Enjoy.

Jobs to do this month
Flowers
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Pick off any developing seedheads on daffodils and other spring bulbs, but leave the foliage to die back naturally
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Finish pruning roses early in the month
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Cut dogwoods, willows, cotinus and paulownia right down to the base to promote vigorous new growth
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Start sowing hardy annuals outdoors, including California poppies, nasturtiums and opium poppies
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Tidy up alpines as they start to flower, removing dead foliage, then mulch with grit to keep the foliage off damp soil
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Plant faded forced bulbs out in the garden for blooms next year
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Plant lilies and other summer-flowering bulbs in pots and borders
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Feed ericaceous shrubs, such as rhododendrons, azaleas, camellias and pieris, with an ericaceous fertiliser
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Tidy up borders, removing established and newly-germinating weeds, then mulch generously with garden compost
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Plant new roses and other shrubs and climbers
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Sow native wildflower seeds in trays or modules, to produce plants for your own mini-meadow
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Check tender new shoots for aphids, and remove before infestations get out of hand
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Continue deadheading spring flowers and any remaining winter bedding so they don't set seed
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Scatter general-purpose fertiliser over flowerbeds and around roses, shrubs and hedges
Fruit and veg
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Avoid carrot root fly by sowing an early crop of carrots under cloches or fleece
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Sow tomatoes, chillies, sweet peppers and aubergines in pots indoors
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Plant Jerusalem artichoke tubers, at a depth of 10-15cm, spaced about 30cm apart
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Buy young herbs to plant in containers near your back door, for handy pickings
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Plant onion and shallot sets, spacing them 10-15cm apart, and keep the bed free of weeds
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Make the first outdoor sowings of hardy veg, such as spinach, covering with cloches or fleece
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Plant early potatoes in trenches on the veg plot, or in large tubs if space is limited
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Sow parsnips as soon as the soil starts to warm up, as they're slow to germinate and need a long growing season
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Plant a fig tree in a large container to restrict its roots, which encourages fruiting and limits its overall size
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Feed cabbages and other brassicas with nitrogen-rich fertiliser, such as pelleted chicken manure
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Plant bare-root asparagus crowns in well-drained soil or raised beds, in an open, sunny spot
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Start hoeing veg beds as soon as the weather starts to warm up, as weeds will germinate quickly
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Plant strawberries in a hanging basket to keep the fruits away from slugs
Greenhouse
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Get crops off to a good start indoors to transplant into the garden later, such as celeriac, celery, lettuces and parsley
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Take down bubble insulation in the greenhouse once temperatures start to rise, to let in more light
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Sow a selection of vibrant annual climbers, such as Spanish flag (Ipomoea lobata) and black-eyed Susan (Thunbergia alata)
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Buy good value young bedding plants for growing on to a larger size under glass, or sow your own in a heated propagator
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Sow dwarf French beans in a large pot for an early indoor crop in June
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Plant prepared freesia bulbs in pots of rich, loam-based compost, for fragrant flowers indoors this summer
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Pot up overwintering cannas into fresh compost, water in, then place in a warm spot to spur them into growth
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Sow sweet peas in deep pots and keep them frost-free in a greenhouse or on a sunny windowsill
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Take cuttings from dahlia tubers planted last month to raise new plants
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Protect greenhouse sowings of beans, peas, mangetouts and sweet peas from hungry mice
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Be vigilant for greenhouse and houseplant pests, such as mealy bugs, and treat straight away
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Open greenhouse vents on sunny days to prevent humidity building up
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Sow coleus on a warm windowsill to enjoy their vibrant foliage indoors or in tropical-style displays outside
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Take basal cuttings from perennials, such as delphiniums and lupins, to root in a pot indoors