Gardening Tasks for Late Spring
Dry and sunny days mark an end to really bad weather and plants soon make up for checks caused by a cold start to the year.
On average, late spring has some of the driest spells of the year in Britain, and in the south the second week of late spring is one of the sunniest. However, thunderstorms are often more frequent than earlier in spring, and these may be accompanied by squally winds. In the north of Britain, snow showers still occur, but snow cover rarely persists for long.
Anticyclone conditions may give hot, tranquil weather in late spring, with daytime temperatures occasionally reaching as high as 27°C (80°F) in southern Britain. But clear nights often bring late frosts, especially ifhas been drier than usual. Eastern regions may experience morning fog and low cloud, giving a grey chilly start to the days.
Late spring is often a stabilizing period during which slow-to-start plants respond quickly to milder conditions and soon make up for any lost time caused by previous poor weather.
Continue hoeing between perennials and shrubs to kill weeds while they are still small. Also continue to stake and support tall plants, such as delphiniums, which are liable to be damaged by winds or rain near flowering time. Pinching out To check the growth of perennials that are inclined to grow too tall, and to make the plants branch out, pinch out the tips. Plants which respond well to this treatment are those that form a leafy clump opening into heads of— such as phlox, golden rod (Solidago), helenium, Michaelmas daisies (Aster) and rudbeckias.
When a plant has reached about a quarter of its expected height, and at least a month before flowering time, pinch out the leading shoots. This may reduce the ultimate height by a quarter, but will not reduce the flowering period —although it may retard flowering by a week or two.
However, if plants are more than three years old and are producing a large number of shoots, that tend to bear inferior blooms, or if you are in a cold district where retarded flowering would be undesirable, it is better to thin out some of these shoots. The shoots which are left on the plant will become more vigorous.
Thin out the shoots at the same time as pinching out shoot tips, or preferably a little earlier. Remove the weakest shoots, concentrating on those at the centre of the crown. Where the shoots are dense, take out up to half the total, severing them close to the ground.
Young plants may require watering during dry spells. Where only a few new kinds have been planted among established plants, use the puddling method.
Scrape away 2.5cm (1in) of the dry topsoil to make a low bank all round the plant or group. Fill the trough once with water — or twice if theis very dry. When the water has soaked away, push back the soil with a rake or hoe.
If a whole newly planted bed is too dry, use a sprinkler or a rose on a watering can or hosepipe. Make sure that the water comes out as a fine spray and not in large drops which tend to pan the soil surface. It is the roots of plants that need water, so be prepared to water the ground a second or even third time.
As soon as the surface begins to dry a little, scratch over with a rake to restore the tilth necessary for aeration.
Plant out garden varieties when all danger of frost is past, using pot-grown plants raised from cuttings, or bought in stock. Insert a cane at each planting hole and tie the stem loosely in place; water well.
Bulbs and tubers
Dead-head, tulips, hyacinths and irises as they finish flowering. If it is necessary to make way for summer bedding, lift daffodils and tulips now, but otherwise wait until early summer.
Heel in lifted bulbs in a temporary bed in a spare corner of the garden so that they can die back gradually. First take out a trench about 30cm (1ft) deep. Lay a length of fine wire or plastic netting in the bottom and then lay the bulbs on the netting. Fill the trench with soil so that it covers the lower half of the stems.
By the beginning of mid summer the stems and leaves will have shrivelled and the bulbs can be lifted for storage. Use the netting as a lever — a sharp pull should lift all the bulbs at once.
Plant crinum bulbs 15-20cm (6-8in) deep in a south-facing border. Or plant them in tubs which can be moved under cover during the autumn in cold regions.
Plant out youngplants —either your own rooted cuttings or bought plants — when danger of frost is over. Dormant dahlia tubers should have been planted out in mid spring, but in colder areas plant them in the first week of late spring.
Tall dahlias need staking as their stems are generally too weak to support the heavy flower heads satisfactorily. For each dahlia, drive a stout stake into the ground at the back of the planting hole before inserting the.
As the stems grow, tie them loosely to the stakes with garden string or raffia. Label each plant. If night frost is forecast, protect the young plants with sheets of newspaper, removing these the next morning.
Tie cordon-grown sweet peas to their canes as they grow. Continue to pinch out side-shoots and tendrils as they appear. Pinch out the first few flowers while they are tiny, but leave the little stems, bearing more buds, which will soon appear.
There is still time to make outdoor sowings of hardy and half-hardy annuals, such as alyssum, calendula, candytuft, cosmos, gaillardia, nasturtium, phlox and tagetes. Hardy biennials can also be sown now in nursery beds.
In mild areas, planting out of half-hardy annuals can begin as soon as the risk of frost has passed. Don’t be persuaded into planting earlier than this by the flood of bedding plants appearing in garden centres — they often bring out stock before outdoor planting conditions are really suitable. If in doubt, it is safer to wait until the first week of early summer.
Water borders and beds cleared of spring bedding before setting out half-hardy annuals.
Give the hardened-off plants a good watering. Remove them from their containers with as much root as possible. Most garden centres sell annuals in strips or boxes made from thin plastic or polystyrene, each plug containing a single plantlet. Remove plants from polystyrene strips by pushing up from the base, those from plastic plugs by pulling the plastic down and away from the fragile root ball.
If you have raised your own seedlings, ease the whole soil and root mass out of the seed tray and cut the plants apart with a knife.
After planting each batch, water with a sprinkler or fine-rose watering can, giving them a good soaking — light watering of young annuals merely results in attracting their roots to the surface.
Rock garden plants
Late spring is the peak period for colour in the rock garden, but weeds are also growing strongly. Use an onion hoe to eliminate small annual weeds. Pull up by hand and destroy any larger perennial weeds. Also remove any unwanted self-sown seedlings of aubrieta, mossy saxifrages and other rock garden plants.
After flowering, trim off the stalks and surplus growth from fast-growing species. This will promote new compact growth and may encourage more flowers — especially with aubrieta.
Sprinkle a mixture of fine soil, sand and granular fertilizer among the green rosettes of sedums and saxifrages if they appear ragged. Allow the mixture to trickle on to the plants through your fingers, then work it in below the leaves and stems. Push further material underneath trailing stems.
Alternatively, if the weather is damp, lift the plants, dig and fertilize the soil, and replant them deeper than previously in close-set bunches.
Tending Rock Garden Plants
1. Destroy weed seedlings between rock garden and alpine plants by hoeing carefully during dry weather. An onion hoe is the ideal size and shape for this purpose. Pull up larger perennial weeds by hand.
2. After flowering, trim aubrieta, mossy saxifrages and other vigorous rock plants to encourage fresh, compact growth. This may also promote a second flush of flowers later in the season and will prevent self-seeding.
3. Sedums, saxifrages and other clump-forming or hummocky rock plants benefit from a sprinkling of fine soil mixed with sand and granular fertilizer. Work this in among the rosettes with your fingers, firming it lightly.
Be prepared to spray regularly to combat rose pests. Spray both sides of the leaves and the stems, using a sprayer that delivers a fine mist. Use proprietary rose insecticides and fungicides — or any type which specifies on the label that it is suitable for— following the manufacturer’s instructions.
Aphids (mainly greenfly), caterpillars,and are the major rose pests and diseases to watch out for. Routine protective spraying gives better results than spraying to eradicate an established outbreak.
Shrubs and trees
During showery weather, complete the planting of evergreens. Keep them moist at the roots after planting, and spray the foliage with water in the evenings during dry or windy weather.
With shrubs that have finished flowering — such as, pieris, and spring-blooming spiraeas — dead-head,
shorten long stems, and thin out or completely remove weak shoots. Also dead-head rhododendrons and azaleas by snapping off the stalks with your fingers, taking care that the new growth buds at the base of the old flower cluster are not damaged in the process. Hedges Clip hedges of Lonicera nitida monthly from now until the end of early autumn to keep them neatly shaped and prevent them from breaking open as they grow. Some other hedges, such as common privet, also need regular clipping to look their best.
Clip hedges of forsythia and flowering currant after the flowers have died. Do not clip them again until the following year, otherwise the flower buds will be removed and the spring display lost.
Apply a liquid high-nitrogen lawn feed to green up the grass. This dressing is especially valuable if the spring fertilizer has been given early.
Water the lawn thoroughly in dry weather. Continue regular mowing, but first check the mower blades for sharpness and correct the setting if necessary. Set the height of cut not lower than 12mm (1/2in) and keep edges neatly trimmed.
In good growing weather, continue to deal with weeds regularly and apply fungicides for disease control.