Late Winter Jobs in the Flower Garden

Jobs to do

Preparing compost for sowing seed under glass

If you have not very much time, you can buy these composts ready made up, but the advantages of making them up yourself are that you do know exactly what ingredients have been used in them, and they cost less. You should never use garden soil for container-grown plants; the alterations in aeration and drainage of the growing medium produced by the physical restrictions of containers result in poor root growth. Composts contain a mixture of ingredients balanced in their proportions and chemical contents so that the plant roots can develop to their maximum.

You will need both seed and potting composts and you can use those that contain soil or the more modern soil-less ones. One of the most commonly used composts is the one called John Innes; this can be bought ready-mixed for use. However, for home mixing you will need the following: 2 parts sterilized loam, 1 part granulated peat and 1 part coarse silver sand (all parts by bulk). To each 36L (1 bushel) of mixture, add 45g (1-1/2oz) superphosphate and 21g (3/4oz) chalk and mix all the ingredients thoroughly together. They should be capable of passing through a 0.6cm (1/4in) sieve. This mixture is the John Innes Seed Compost.

The soil-less seed compost contains sphagnum peat and fine sand, usually in a 75:25 mixture, with lime and fertilizers added. There are many different formulae for these soil-less composts, depending on the plants and their needs and it is probably quicker and more satisfactory to buy them made up rather than make them up oneself and run the risk of damage to plants through wrong or excessive use of the ingredients. It is a matter of personal preference which you use, and you will probably find in time that you get better results with one or the other.

Preparing compost for potting

As with the seed composts, you can make up those needed for potting in advance; give them at least a week to mature before using and leave them in the greenhouse to warm up to the surrounding temperature.

The John Innes potting compost contains the following: 7 parts sterilized loam, 3 parts peat and 2 parts coarse sand (by bulk); to 36L (1 bushel) add 120g (4oz) of fertilizer made up as follows: 2 parts superphosphate, 2 parts hoof and horn meal and 1 part sulphate of potash (parts by weight). The compost should also have 21g (3/4oz) chalk added to every 36L (1 bushel).

This mixture is the J. I. Potting Compost No. 1; there are two more – No. 2 contains 240g (8oz) of fertilizer and 42g (1-1/2oz) chalk per 36L (1 bushel), and No. 3 has 360g (12oz) of fertilizer and (63g (2-1/4oz) of chalk per 36L (1 bushel). Some gardeners occasionally need a No. 4 mix, for certain very vigorous plants.

The No. 1 potting compost is used for small plants growing in pots from 5-10cm (2-4in) in diameter; No. 2 is suitable for those in pots from 12.5-17.5cm (5-7^), and No. 3 for the larger plants, in pots from 20cm (8in) in diameter and larger. However, this is not a rigid rule; fast-growing plants may need the No. 2 in a 10cm (4in) pot and No. 3 in a 17.5cm (7in) pot. Others flower better if slightly starved, so will be all right in No. 1 for longer, and you will be able to vary the composts as you gain experience.

There are soil-less potting composts, too, consisting of a peat and sand mixture, to which fertilizer and lime are added. Such composts for potting are not as useful, as they have much less in the way of food reserves. Because they are light in weight, the large and medium-sized plants are top-heavy and tend to fall over, but for small plants they can be ideal, as they are exceptionally well-aerated and drained; some plants grow better in them than in the John Innes type.

When you become experienced at container cultivation, you can vary the contents according to the plants you are growing, so that the composts are tailored exactly to the plants’ needs. For instance, cacti, not surprisingly, thrive in gritty mixtures, so you can mix an extra part of very coarse sand or grit into the basic potting compost; pelargoniums naturally grow in poor but well-drained soils, so their composts can also be given more drainage material. For cactus seed, the J.I. Seed compost with about 1/4 part sand added to it will be good; they also germinate and grow surprisingly well in a soil-less seed compost – surprisingly, since their native habitat is gritty, to say the least.

Sowing seed in containers

Seed to sow in containers in late winter, during the last week, consists mainly of the half-hardy annuals and bedding plants: those which grow comparatively slowly and which are on the small side. Otherwise, by sowing at this time, you will be faced at the beginning of late spring with plants more than ready to be planted outdoors, when the weather may still be rather chilly, even for hardened-off plants. You can also sow seed of some tuberous plants: large-flowered begonias, dahlia, gloxinia (sinningia) and streptocarpus.

Wooden or plastic seed-trays are probably the most convenient containers to use, divided into sections, but pans are also very handy and, if any seeds are large, individual plastic, clay or peat pots can be used. Peat pots avoid the need for pricking out, as the whole pot can be planted or potted.

Fill the containers, press the compost down with the fingers at the sides and the corners first and then in the centre, and level the surface. Add more compost if necessary so that the final level is about 1cm (1/2in) below the top of the container and firm with a presser. Put partially in a tray of water so that the moisture is gradually drawn up through the compost; when the surface is obviously damp, remove the container and put to drain off the surplus water.

Sprinkle the seed evenly over the surface of the compost; if you sow it in clumps, the seedlings are more likely to be infected with damping-off, a damaging fungus disease. Sterilized loam avoids this, or watering them with a fungicide. Cover the seed with twice its own depth of compost, sieving it through a very fine sieve. If the seeds are minute, as begonia and cactus seeds are, don’t cover them at all, simply press them into the surface. Cover the container with white plastic sheet, or brown paper and a sheet of glass, and put in a temperature of 16-18°C (60-65°F), away from the sun.

You can vary these practices with experience; some seed germinates better in the light than in the dark and others need a higher temperature for germination or germinate more quickly with more warmth.


Plants needing potting now may be schizanthus, rooted chrysanthemum cuttings and root cuttings which have taken. The schizanthus sown in late summer should be put into their final 15cm (6in) size pots, if this has not already been done, potting them firmly and re-staking if necessary. Chrysanthemum cuttings taken in mid-winter will need potting, into 5 or 9cm (2 or 3-1/2in) pots, depending on the root development, and root cuttings taken at the same time will need similarly-sized pots.

hippeastrums, also known as amaryllis, are tender bulbous plants for the greenhouse or home

Hippeastrums can be retrieved from under the staging and started off again sometime during late winter. They quite often start themselves off , like cyclamen, but whatever state they are in, the compost can be watered moderately and the pots put on to the staging and into the propagator, if possible with a temperature of about 16°C (60°F). When the tip is obviously sprouting well, take them out of the propagator; the top 2.5cm (1in) of compost can then be removed and replaced with a topdressing of fresh. This can be done annually for three or four years before there is a need for complete repotting, as hippeastrums grow better if undisturbed. However, they do need regular feeding during the growing seasons when they are not repotted. Give them as much light as possible.

Pruning/cutting back greenhouse plants

Late winter is, in general, the best time to prune ‘undercover’ plants as early spring is when they start to grow again. In the cool greenhouse, the plants that will need pruning are climbers and fuchsias; pelargoniums can also be cut back now if they were not done last autumn.

Fuchsias should be pruned so that last summer’s flowering shoots are cut back to leave one or two pairs of dormant buds, so that there is a kind of stub left. Older plants can have the main stem itself cut back by about half its length, to just above a good strong sideshoot, unless it is being grown as a standard. Short, thin shoots should be cut right off and the remainder thinned if crowded.

Passion flowers can be pruned by removing all the weak shoots completely and cutting the strong shoots down to leave two-thirds of each stem. Hoya needs a little pruning to cut back straggling shoots to shape, and one or two of the oldest stems should be cut back by about a third. Trailing plants like tradescantias will probably need hard cutting as they are often very straggly at the end of the winter, so you can reduce the stems to about 7.5cm (3in) long. Pelargoniums can also be cut down hard, to leave stems about 10 or 12.5cm (4 or 5in) long. Remember that pruning cuts on all plants should always be made cleanly, just above a dormant bud or sideshoot, with no stub left.


You can continue to take cuttings of late-flowering chrysanthemums and, throughout late winter, early-flowering kinds will be producing suitable new growth, especially if the weather is getting markedly warmer.

Starting corms and tubers

Achimenes, large-flowering begonias, gloxinias (sinningias) and streptocarpus can all be encouraged to start growing by putting them into seed boxes containing moist peat. They should have the top of the corm or tuber just above the peat surface, except for the achimenes, which should be slightly below it. Space them out so that they do not touch one another. If you have room to put them in the propagator, they will come on more quickly.

General greenhouse work

Start watering plants which have been dormant; some may have already begun to grow, but only give moderate amounts at first, just enough to moisten the compost right through. Do not saturate it. Give a little more ventilation, especially on sunny days, when you can turn the heat off altogether in the middle of the day provided the temperature outside is above freezing. Tidy out the winter accumulation of debris, fallen or rotting leaves and stems, scrub any green mould off the outside of containers, brush down staging and floors and generally give the greenhouse a mild spring clean.

Outdoor work

If the weather allows, top the lawn, brushing the grass first; also start a new lawn from turf. The tubers of the florists’ anemones (St Brigid and de Caen strains) can be planted outdoors. Medium to light, sandy soil suits them and a sunny or lightly shaded position. Rotted organic matter should have been dug in some months earlier. Put the tubers 6.5-7.5cm (2-1/2 – 3in) deep and about 15cm (6in) apart.

A general clearing up of leaves, twigs and other rubbish now will give you more time in spring; weeding can sometimes be done on fine days. Break the ice on pools if there are any fish in them and remove any leaves burying overwintering annuals.

30. August 2011 by admin
Categories: Flower Garden, Types of Gardens | Tags: , | Comments Off on Late Winter Jobs in the Flower Garden


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