The lawn at this time of the year always looks rather sorry for itself, thin, limp and messy with leaves and twigs. As the temperature rises and the grass starts to grow, you can help to revive it more quickly and strongly by raking, brushing, topping and spiking, in that order. This work results in aerating the soil and the turf and removing possible pests.
Use a springbok rake, rake first in one direction and then at right angles across this; next brush, using a stiff brush to bring the grass upright and then cut the grass. Set the mower blades high, so that the grass is left about 2.5cm (1in) long; a harder cut can be given at the next mowing. After cutting, with the collecting box on, spike the lawn -you can use an ordinary garden fork for this. To do any real good, the tines should penetrate 10cm (4in) deep, but 7.5cm (3in) is better than nothing. Do this all over the lawn, about 12 or 15cm (5 or 6in) apart.
Rolling a lawn, to keep it level, used to be considered essential but nowadays it is thought to do more harm than good, by compacting the soil, especially since modern mowers have a roller fitted automatically. If there is moss on the lawn, raking should not be done until the moss has been treated, since raking only serves to spread it.
Moss thrives in damp conditions; it will spread rapidly in wet weather, but it will also appear where the soil is extremely acid, where it is compacted and lacking in air and where it is lacking plant food. In all these conditions, the lawn grasses become weak and cannot compete with -invaders. Moss can be burnt out with lawnsand bought ready-mixed, or made up at home of 3 parts sulphate of ammonia, 1 part calcined (burnt) ferrous sulphate and 20 parts sand. This mixture is applied dry at 120g per sq m (4oz per sq yd); it must be put on evenly, otherwise the grass may be permanently damaged, and watered in if there is no rain after 48 hours. The grass is likely to be discoloured, brown or blackish, but this is temporary. When the moss is black and dead, then it can be raked away.
Proprietary moss killers containing mercury can also be used and there are one or two mercurize4 lawnsands available; the mercury will kill the moss spores as well as the vegetative growth.
However, for the permanent eradication of the moss, conditions for the growth of the grass must be put right and this means that you must ensure good soil aeration, an adequate food supply, frequent cutting to avoid the shock given by occasional very hard cutting, and a sufficient water supply in hot and/or dry weather. It is mostly summer droughts and watering long after it was first necessary that result in the invasion of the turf by coarse, and weed grasses, weeds, moss and disease.
You can put achimenes, large-flowered begonias and gloxinias (sinningias) to sprout in moist peat if this was not done last month, but not in the propagator; the greenhouse will be sufficiently warm, if you are maintaining the minimum temperature. It is quite likely that some of them have already started to produce new shoots. Dahlias can be started as well, to provide shoots for cuttings. Take off any rotting tubers and put the healthy crowns in 15cm (6in) deep boxes, covering the tubers with moist peat or soil.
By now, the seeds sown last month in the propagator will be seedlings that need pricking out; they will include half-hardy annuals, and such slightly tender bedding and greenhouse plants as begonias (fibrous-rooted and large-flowered), dahlia, gloxinia (sinningia) and streptocarpus. In general, seedlings should be moved when they have two seed leaves and the first true leaf just appearing, in other words when they are large enough to handle. Lever them out, breaking the roots as little as possible, and drop each seedling into a hole in the compost which is large enough to prevent the roots being cramped, and deep enough to ensure that most of the stem is buried; the leaves should be just above the compost surface. Space them 5cm (2in) apart each way.
Quite often each seedling has a long main root or tap root; if you look closely at the tip of this, you will see that it finishes in a kind of rounded point, and it is there that the seedling takes in most of the food it needs. If that gets broken off, it will have to rely on the much less strong side roots to absorb food and may even have to grow a new root. While this is happening, it cannot absorb sufficient water, and this is why so many pricked out seedlings wilt as soon as they are moved. Clumsy lifting can damage a seedling so that the mature plant is never strong. Another important point in pricking out is to do it as soon as the seedling can be handled. The shock of moving is much greater when they are larger and there will be much more root to handle (and to damage); they may even have run short of food.
Once firmed into the compost, the seedlings should be gently watered with a rosed watering can and put in a shady place; a polythene tent over them will keep the atmosphere moist and help to stop any tendency to flag.
Plants which are grown permanently in the greenhouse will need new compost every one or two years; if they are not particularly strong or fast growers, they can simply be topdresscd, instead of completely repotted. Cuttings which were put to root last month may need potting into individual pots by now.
Plants to repot could include all foliage plants, such as tradescantia, zebrina, chlorophytum, asparagus and ferns, summer-flowering plants such as pelargoniums (geraniums), the Italian bellflower (Campanula isophylla), jasmine, fuchsia, hoya, cacti and other succulents, cobaea (cup-and-saucer plant) and passion flower (Passiflora caerulea).
In general, use a pot one size larger than the one the plant is in, and do not disturb the root-ball unless the roots have become very long, when they can be cut back to the root-ball, and the ball loosened a little. If the maximum size of the plant has been reached, use a pot the same size, but remove all the compost carefully from the roots, put a little new compost in the pot, and centre the plant on this, so that compost can be crumbled in evenly all round the roots.
When you repot, have the new compost ready in the greenhouse so that it is at the same temperature as that in which the plants are growing and use completely clean pots, plastic or clay. If new, clay pots should be put to soak in water for about twenty-four hours, otherwise they will absorb all the water you give to the compost which is intended for the plant and you will constantly be watering but getting poor plant growth. Put drainage material, such as pieces of broken clay pot, in the base of the clay pots, and then repot the plant.
Cacti can be difficult to handle because of their prickles; gloves will help and tongs are even better, the kind that form two halves of a ring, as they do least damage to the spines.
Pelargoniums which have been overwintered in the greenhouse can now be transferred to individual pots about 15 or 17.5cm (6 or 7in) in diameter, whatever size will take the roots without cramping them too much. Use the J. Innes potting compost No. 2 with one part extra of coarse sand added, as pelargoniums like well-drained soils.
Topdressing consists simply of removing the top 2.5cm (1in) or so of compost and replacing it with fresh. Plants treated like this will need to have liquid feeding started much earlier than repotted plants. Hippeastrums can be started now if this has not already been done.
Cuttings, such as early- and late-flowering chrysanthemums, which rooted last month, may also need potting now into their own pots. Pelargonium cuttings which were rooted last autumn can now also be transferred to larger pots.
At some time during early spring, if not before, late-flowering chrysanthemums will have grown to about 15cm (6in) in height and should be stopped, to induce them to produce sideshoots and more flowers in due course. Stopping is a way of halting the upward growth of the main stem completely, and diverting the plant’s energy into the production of side growths from the axil of the leaves. Most chrysanthemum cultivars tend to produce these growths in embryo, but they do not develop, unless the plant is stopped. To stop the plant, the growing tip and first pair of leaves are pinched off between finger and thumb.
Since the outside temperature is rising and plants are beginning to grow, you can dispense with artificial heat on sunny days, though it will still be necessary at night. Ventilation can be increased during the day and condensation should cease to be a problem. Pricked-out seedlings and potted cuttings will need spacing out as they grow, to avoid their becoming drawn; the need for water will steadily increase and germinating seeds must have an eye kept on them constantly, to avoid sunburn, drought and overcrowding because the pricking out has not been done quickly enough.
In early spring, most weeding will be a matter of clearing off any weeds that have managed to survive the winter after a late germination last autumn; however, lawn weeds are best left until late in mid-spring. Where seeds are sown outdoors, weed seedlings should be dealt with as soon as they become obvious.
Beds and borders will need tidying to remove leaves, twigs and other debris. Rock gardens especially can be very messy after the winter: some plants need cutting back to remove dead growth, the soil needs forking lightly with a hand fork, and grit or gravel replaced where rain has washed it away. If conditions are dry enough, you can burn off the dead leaves and stems of pampas grass, otherwise cut them off and rake out debris from round the plants.
Last year’s compost heap can be used as a mulch for permanent plantings, if a mulch was not given in the autumn, otherwise it can be kept for later use. A new heap can be started with this year’s weeds and grass cuttings.
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