If the weather has been mild, tender plants in containers are probably in a cold frame but they should definitely be taken under greenhouse cover sometime during the next few weeks.
Hardy annuals, bedding plants and half-hardy annuals will have come to the end of their flowering and should be cleared off and put on the compost heap, leaving the ground ready for digging in late autumn. The aquatic plants will be dying back fast and their remains should be cleared out of the pool, together with leaves as they fall.
Herbaceous perennials and rock plants can be cleaned up by cutting off the flowering stems and leaves to crown level but it may be more sensible to leave them. Although it makes beds and borders look gaunt and untidy, the dead growth does provide protection from cold; this protection can just make the difference between life and death for some plants in a bad winter.
Dahlias can be left until the first frost, in mid or late autumn but once their leaves and stems are black, the remain: should be cut off, the tubers dug up and the soil shaken off Tubers which are firm and uninjured can be stored in a frost-proof place through the winter; they should be put into 7.5cm (3in) deep boxes, in the bottom of which is a layer of peat, dry leaves or straw. Peat or soil is then worked in between the plants after they are placed in the box, to cover the tubers. Dusting them with sulphur beforehand will prevent the spread of storage rots.
Keeping the storage material slightly moist prevents the tubers from wrinkling and if placed under the staging and kept at about 7° C (45° F), they will tick over until spring. In its native habitat, the dahlia is a perennial and sometimes, in temperate climates, tubers left in the ground all winter survive and flower the following season, though not as well as new plants grown from cuttings.
Pelargoniums which have been planted outdoors all summer should be cut down to leave about 10cm (4in) of the main stem, dug up and put into pots or boxes containing compost; it will do no harm if they are slightly cramped for root-room. The containers are then transferred to the greenhouse staging.
Early-flowering chrysanthemums, the last flowers of which should have been cut by the end of mid-autumn, an another plant to move into shelter. Cut the top growth down to leave about 10cm (4in) of stem and put the crowns packed closely, into boxes of compost or fine loam. Then put the containers into a cold frame for the winter, closing it when frost is forecast.
Large-flowered begonia tubers should be dug up and boxed, in peat, to go under the staging. Gladioli will have to be taken up, cleaned of any top growth and any small cormlets which have formed round the base, and put in single layers in seed trays in a dark frost-proof place.
Sweetpeas sown in early autumn will need stopping: break off the tip of the main shoot just above the third pair of leaves. If this leading tip is allowed to grow, the resultant plant will be poor, if it ever reaches any length; its removal encourages two side-shoots to appear just below and these should be kept and used for training. They will need temporary support through the winter and any other side-shoots should be removed as soon as seen.
Towards the end of mid-autumn one of the biggest autumn clearing-up jobs will start, that of sweeping up and removing leaves. In some years the autumn gales will largely do the job for you but leaf removal from lawns is important because leaf cover, if left to lie, discolours the grass and weakens it.
Leaves stacked separately from the general compost heap, with a wire-netting surround, rot down into good organic matter within a year; sieved leafmould used to be an ingredient of potting composts, before peat became so easily available. Leathery leaves, such as those of evergreens, which are shed at times, take so long to decay they are not worth including; oak and chestnut make excellent leafmould.
Summer-flowering tubers and corms in the greenhouse will be finishing their displays and as they do so, the dead and dying growth should be cut off and the containers put on their sides under the staging. There is no need to remove the tubers and corms from the compost; they can remain in it through the winter. Nerine sarniensis is the exception, as its leaves last through the winter; it should be watered occasionally, given a light place, kept free from frost and reasonably warm if possible. In spring it dies down and then rests through the summer.
Established herbaceous borders can be supplied with bone-meal now to good effect, also permanent plantings of spring-flowering bulbs; apply 120g per sq m (4oz per sq yd), preferably when rain is due. There is no need to continue feeding late-flowering chrysanthemums; in fact, it can damage them if continued later than mid-autumn.
This is a good time of the year to dig up herbaceous perennials and divide them. This job needs to be done about every four years, otherwise the plants flower less and less well. They should be taken up with as much root as possible intact; cut back very long ones to the main body of the root-ball. The plants are then divided, either by gently pulling them apart, by using a knife for solid crowns, or by using two forks, back to back. Replant the outside pieces and put the central parts on the compost heap or destroy.
Damping down should cease, feeding will not be necessary any longer and watering can be considerably decreased. Ventilators will need to be closed very much more at night if the temperature drops and for the daytime they will need regulating from day to day, as the weather will be changeable. Gentle artificial heat will be needed some nights and towards the end of mid-autumn is a good time to line the inside of the greenhouse glazing with clear plastic sheet to retain warmth. It is now possible to obtain sheet on which moisture does not condense. Grey mould (botrytis) tends to spread rapidly in autumn, so be careful to remove fallen leaves and stems. Watch for the disease on the plants; flowers can be infected just as much as leaves can.
Mowing will almost be unnecessary by the end of mid-autumn. The compost heap will be finished and can have a roof put above it to keep the worst of the winter wet off, weeding will be more or less at an end and pest and disease treatment will no longer be required, except for leather-jackets on lawns.
These grey-brown caterpillars are the larvae of the cranefly (daddy-long-legs); they hatch from eggs laid earlier in autumn in the soil and then feed on the roots of grass and also small plants. When adult they are about 2.5cm (1in) but the small caterpillars can do a lot of damage, feeding in groups in autumn and through the winter in mild weather; infested grass turns pale brown and dies, in roundish patches. Starlings digging into the turf are often a sign of their presence; watering it heavily, then covering overnight, brings some of them to the surface, where they can be collected and destroyed the following day.
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