Jobs to do in the garden this week.

Prune overgrown or newly planted blackcurrants back hard - almost to ground level, this will 'open up' the plant and encourage new shoots, producing fruit the following season. Blackcurrants mainly fruit on last year's growth. Normal pruning is restricted to removing the old fruiting branches, just after fruiting, leaving new shoots to bear fruit next year.
Now's a good time to service your lawn mower. If you've got an electric mower it's just a matter of checking the blades aren't too badly damaged (if they are the plastic type, they are easily replaced) and that the underside of the deck is clear of debris. For petrol mowers it's a bit more complex. Remove the air filter cover and give the filter a good vacuum. Lift the mower onto a bench and examine the underside of the mower deck and the state of the blade (note that most manufacturers suggest not tipping the mower unless it has been drained of oil as well as any petrol), remove the spark plug and check that the spark gap is bright, if not give it a clean with some fine emery paper and reset the spark gap. Old petrol from last year will be 'stale', making it difficult to start your mower. Mix it with some new petrol in your fuel can. For the first start of the mower I find a short spray from a can of Easy Start into the intake will get the mower going pretty quickly.
After a frost try to stay off the grass. Treading on the lawn in frosty conditions can damage the grass.
Pelargonium/geranium cuttings can be taken now. Cut off a 8cm (3in) shoot just below a leaf joint (node), remove all but the top pair of leaves and insert the cuttings 4cm (1.5in) into a small pot of potting compost. Gently water in the cuttings and place in a warm, well-lit place. When they have begun to produce more leaves they can be moved to larger pots, containing general-purpose compost.
Order bare root roses. Bare root roses are cheaper to buy and have posted than container-grown roses. There is also a much broader range of roses available by mail-order than can be purchased in most garden centres.

Ordering early and planting within the first few weeks of October will allow them to start to get established before the hard winter frosts, but planted later in the winter/new year (up until the end of April), they'll still settle in quickly, begin to sprout and flower in the summer. When planting a bare root rose in winter you'll initially need to water it in well, but unless we have a particularly dry spell it shouldn't need additional watering, if planting in early spring, you'll need to keep an eye on the weather and water regularly to stop the roots from drying out.
Put holly branches on the ground to stop mice and squirrels digging up newly planted peas, broad beans and bulbs.
Plant lily and gladioli bulbs in 4in (10cm) deep holes. Cover with soil or compost and gently firm down the soil to ensure that there are no air pockets as this may cause the bulbs to rot.
Cut vigorous climbers such as honeysuckle and ivy back hard.
When you see the new shoots forming on sedum, cut down the old, dead flower heads.
Refirm the roots of any shrubs that may have been lifted by frost.
Tidy up any remaining leaves and general garden rubbish. It's home to slugs, snails, vine weevil and woodlice and can introduce disease and infection into your garden.
April is the peak flowering time for orchids.
April is the best time to plant an evergreen, such as laurel or box.
Keep an eye on the weather forecast. Cover shrubs that are likely to be damaged by frost with garden fleece, sacking or an old light blanket.
Don't be tempted to buy your summer bedding yet, unless you have a greenhouse, conservatory or cold frame that you can store them in. A late April / early May frost is not uncommon in the UK.
Prune lavatera hard, down to healthy young growth.
Now is the best time to plant lavender. Widely grown for its scent and foliage, lavender is ideal for borders or a low hedge. Available in shades of purple, blue, white and pink it is a magnet for bees and butterflies
Postion plant supports where they will be needed in late summer. Doing this now reduces the risk of damaging the roots later in the season.
As summer-flowering herbaceous perennials start to come back to life, lift and divide overgrown plants.
Plant onion sets (bulbs). Run a string line across the bed and plant the bulbs, 5-10cm (2-4in) apart, up to their necks so just the tips are showing. Space the rows 25-30cm (10-15in). Firm the soil around them and water well, cover with a cloche for added protection. Keep an eye on them until they get established as some birds like to pull the sets out.
Begin regular cutting of your lawn. If the grass is long increase the height adjustment of the mower to the highest setting. Once this first cut has been done, lower the blades/deck and go back over the lawn.
Remove algae and moss from patios and paths with a pressure washer or proprietary patio and path cleaner (traditionally a tar oil winter wash could have been used, but these are no longer available, particualrly to the amateur gardener, as they were found to be carcinogenic).
If your lawn is more moss than grass, then treat with a lawn moss killer. Bare in mind that the moss will turn black within a couple of days, so don't be too alarmed. A couple of weeks after application, if you are left with bare patches in your lawn, mix equal quantities of grass seed and seived compost and scatter over the patches, cover areas with fine netting or twigs gently pushed into the soil, to protect from birds and animals. Combination lawn feed and moss killer is available, but feeding your lawn when it's not necessary will encourage it to grow quicker and therefore need to be cut more regularly.
Scatter growmore granules under fruit trees and bushes, especially apple, pear and plum trees. If it doesn't rain for a couple of days, water the granules in with a hose or watering can. Growmore is a slow release, general fertiliser, it includes the three main plant nutrients (nitrogen, phosphates and potassium).
Transplant any self-set aquilegia, lupins and hollyhocks to new locations.
As it's starting to warm up, it's a good time to lay a new lawn, although the best time is in Autumn or late winter, as it's damper and cooler, allowing the turf to bed in without you having to worry too much about regular watering. See here: laying a new lawn for further information.
Remove the dead heads of spring flowering bulbs, such as tulips and daffodils, before they have a chance to produce seed. This will encourage the plant to store energy in the bulb rather than wasting it on seed production.
Your pond may have started to turn green and cloudy. This is due to a rapid increase in algae, which flourish in the warmer spring temperatures. Once the pond plants start to grow again, especially the oxygenating plants, these will use up the nutrients and create shade, reducing the amount of algae. To speed up the clearing of the water, drop a small string bag/pair of old tights stuffed with barley straw, into the pond. Weigh the straw down, so that it floats just below the surface of the water.
As the straw breaks down, it produces hydrogen peroxide, which reduces and inhibits the growth of algae and blanket weed. If the algae is particularly bad, barley straw extract can be bought in liquid form and added to the pond water (follow the instructions on the bottle, but as a guide before purchasing,125ml treats approximately 4,500 litres/1,000 gallons, but multiple, fortnightly treatments through the year may be necessary). If you have a fountain or waterfall, try to position the barley straw underneath this. Remove and replace the barley with new straw after about six months, before it completely rots down, polluting the water.
The small, pre-filled barley straw bags to add to your pond, cost about £2 each, but you can buy a 17 litre pack, which will last a few years for about £10 from your local pet shop or Amazon here: Supreme Petfoods Tiny Friends Farm Russell & Gerty Barley Straw, 17 Litres
Sow vegetable seeds (courgette, marrow, runner and French beans) in the vegetable patch and salad seeds (lettuce, spring onion and radish) little and often to provide a staggered harvest through the summer.
Spread compost from the compost bin over the borders and vegetable patch. This adds valuable nutrients to the soil and acts as a mulch, to retain moisture and reduce weed growth. The ground should be weed free and the soil moist before adding a layer of compost or mulch.
To reduce the chance of introducing infection when pruning or deadheading, wipe the blades of secateurs, loppers and snips with a rag soaked with a garden disinfectant, such as Jeyes fluid, which can also be used to wipe down garden tables and chairs.
Lift, divide and replant chives.

Jobs to do in the garden this week.

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