Raising Plants from Seed

To many gardeners the problem of exactly when to sow seed is a difficult one to solve. Often when the book says sow at a certain date, either soil or weather conditions may be quite unsuitable, and sometimes both are. The fact is that it is more important for the soil to be in the right condition than it is to sow on a particular date.

Sometimes in the past there has been a too-rigid adherence to the belief that unless seed is sown at a specific time the resultant crop, whether flowers or vegetables, will not be satisfactory.

The soil is right for sowing purposes when it can easily be worked with a rake, when it crumbles freely and does not pull up when the rake is moved over the surface. A dry, dusty condition is not required. The three essential needs for free germination and good growth are moisture, warmth and air. Moisture will come from the soil, but if the ground is too wet there will be no room for air.

Raising Plants from Seed

This is, of course, one of the reasons why the seed-bed should be made where there is no possibility of water draining on to, or remaining on, the seed. For warmth we usually rely on the sun, although this is where cloches and other glass structures can be useful, since if placed over the soil a week or two before the seed is sown the soil temperature will be raised considerably. Ideally, the right soil temperature for easy, good germination is at least 50°F. In practice it is very often considerably lower. So long as it is well above freezing point, this does not really matter, for it will only mean that the seeds will be slower in starting into growth. The temperature of the soil is influenced by the amount of moisture it contains, so that a wet or damp soil will not be ready for seed-sowing as early as one which is well drained. Having very carefully prepared the seed-bed, it is merely spoiling the results likely to be obtained if any attempt is made to sow at an unfavourable time.

Outdoor sowing should always be done on a calm day, otherwise the seed will blow about and fall irregularly, or get lost.

When completing the seed-bed preparatory to sowing, an important point is to see that the surface is level, for if there are undulations, even when the rows are made straight, it is certain that the seed will not be evenly covered. This means there is bound to be some irregularity in the time the seed takes to germinate, for the deeper it is buried the longer it will be in breaking through the surface. Worse still, if very minute seed is covered too deeply in proportion to its size it may not germinate at all.

Where hillocks and depressions occur, the latter may become waterlogged in wet weather, whereas when the site is dry and there is drought, the hillocks may become parched and the seed scorched to death.

Soil temperature plays an important part in regard to germination, and this is why it should be kept as even as possible and why both sodden and parched conditions must be avoided. After levelling the surface (and this will also mean the removal of any large stones) it is wise to tread the plot so as to make the bed firm. Keep the feet close together and, in a shuffling manner, tread evenly and regularly all over the bed, preferably in systematic lines. Then lightly rake the surface in such a way that no soil is moved deeply.

This initial good soil preparation will make the subsequent operations much easier. Most seeds are sown in rows, although in the case of hardy annuals more pleasing results are obtained if clumps or groups are planned, for when in bloom a more natural effect is obtained, especially as all the flowers may not be cut but some left to beautify the garden. Although possibly not an ideal method, seed can be broadcast. It is essential that this should be done evenly and thinly, otherwise the result will be both thick patches of plants and bare spaces.

There are various ways of making the rows which should, of course, be straight, since a crooked row looks slovenly. A garden line, stretched where the rows are to be made, will ensure that they are straight and tidy looking. A shallow depression should be made along the side of the line so as to show the ‘trench’ in which the seed is to be dropped. For small seeds, some gardeners simply press a broom handle or rod into the soil. For larger seeds, the back of the rake may be used, with the teeth pointing upwards, or the corner of a draw hoe pulled through the soil along the line will be satisfactory. For even bigger seeds, the rows may be taken out with a hoe or spade.

The space allowed between the rows is largely decided by the type of flower-seed being sown. With hardy annuals which are being grown solely for cutting purposes, much will depend on how tall the plants are likely to grow, and if they are bushy or slender. There must always be room for natural development, to enable the full quantity of flowers to be produced. It is essential to sow evenly, for seed obtained from reputable firms will under ordinary conditions germinate well, and it is both a waste of seeds and a hindrance to their growth to crowd them in narrow drills.

Some thinning out can be done with many, perhaps most, annuals.

Most of us are loth to do this as drastically as we should. Some of the very popular kinds, such as cornflowers, nigellas, larkspur and escholtzia, resent root disturbance and do not transplant satisfactorily, except in very showery weather. If they are left bunched together in rows, however, they will never give good results. If it is found that there are too many seedlings, they should certainly be thinned out early on, for if the seedlings suffer a check through being overcrowded, they often fail to outgrow it.

Having sown thinly and covered the seed according to its size, it then becomes a matter of waiting for growth to be seen. Sometimes the seedlings will be through the soil a week after sowing, but in the majority of cases it will be 12 days or more before anything is seen.

Occasionally some rows or patches in the row will germinate before others, but this is nearly always due to local conditions or variation in soil mixture or aspect.

Although the soil should never be allowed to suffer from drought, and during continued dry weather it may be necessary to apply water to the rows, this should be done only when really necessary. A finerosed can should be used, and it is better to give a few really good soakings than many daily dribblings.

The disadvantage of starting to water seedlings is that it causes the young roots to come to the surface, instead of working their way down into the soil where there is moisture. This in turn means that the roots so near the surface easily suffer during times of drought and the little plants may soon flag and die.

During a prolonged spell of dry, sunny weather, twiggy boughs carefully placed over the seed-bed will prevent the rapid drying out of the soil and provide shade for the delicate seedlings which are just emerging through the soil, and prevent them from being shrivelled up. Young plants are not liable to suffer nearly so much, if at all, if the seed-bed is well enriched with humus-forming material. This is why it is advisable to work in plenty of organic matter when the site is being prepared, for then they do not dry out quickly, and produce really good plants with plenty of roots.

It nearly always happens that following the good preparation of a seed-bed, a crop of weed seedlings appear. This does not of course indicate that your seedsmen has included weed-seeds in the packet. There are weed-seeds in most soils, and when conditions are made favourable they germinate freely, although they may have been dormant for many months, even years.

Apart from the open-ground sowing of some hardy annuals in the autumn, there are many which may be brought through the winter

successfully, with the use of cloches. This will result in plants which flower earlier than the uncovered crops and therefore give a longer season of cutting. Particularly in southern districts, annuals sown under cloches in September will result in the production of tough, hardy plants with a really good rooting system, enabling them to stand the extremes of winter and spring weather. They will bloom as much as 3 or 4 weeks before the spring-sown annuals, and will not suffer from drought, since their roots will be deeper and better able to find moisture in the sub-soil.

Good soil preparation is necessary, but not very rich or highly manured ground, since this would lead to quick, sappy growth and flowers of poorer quality. If before sowing is done, towards the end of September, a thick layer of ‘ripe’ compost is dug into the top 6 or 8 in. of the site, it will be most valuable. An average barrow load of compost will dress about 4 sq. yds.

A fairly light, well-drained soil in a sunny position is desirable. It is essential that the seed-bed should be level, firm and brought down to a fine tilth. For larger seeds, such as larkspur and nigellas, a covering of I in. is sufficient, but for very small seeds, such as clarkia and godetia, only a very light covering is necessary.

Sow thinly and after covering the seed see that the glass ends are fixed to the clothes to exclude draught. Early thinning of the seedlings is necessary, and is best done in two stages, first to 2 in. apart when the seedlings are an inch high, and then about a couple of weeks later make the final thinning to leave the plants gin. Apart. The clothes must be removed before the leaves touch the glass in March or April, although in cold or northern districts the cloches may be raised by using adaptors. After de-cloching, make sure that the soil remains uniformly moist without becoming waterlogged. Should there be severe cold at night soon after the cloches have been removed, they can be replaced temporarily.

Some kind of support will be helpful in preventing the young plants from being flattened by wind and heavy rain. Bushy sticks inserted at intervals, or strands of string run each side of the rows supported by bamboo canes every yard or so, are sufficient. Should the weather become very hot and dry in the spring, a mulching of compost around the plants will keep the roots cool and prevent the soil from drying out.

Apart from the plants mentioned, there are a number of other annuals which will do well when grown under cloches, including those recommended for sowing in the open. Some of the annual chrysanthemums are suitable, and there is usually an increase in the height of the stem, a desirable feature for all cut flowers. The tricolour varieties are not reliable during the winter, and it is wise to keep to the golden yellow, ‘Evening Star’, and the light primrose, ‘Morning Star’, which are both very attractive when cut.

The pink larkspur, ‘Los Angeles’, responds well to cloche conditions, and two rows can be put under the normal cloche width. With some of the other items, such as Nigella, ‘Miss Jekyll’, two rows may be sown or, if preferred, one row down the centre of the cloche and a row of lettuce each side, which will produce usable plants early in the season.

Calendula ‘Radio’ and ‘Orange King’ are dependable. Two rows are sown to a cloche, the plants finally being thinned so that they stand 6 in. apart. The first calendula flowers from the covered bed are usually short-stemmed, but subsequent blooms will give a good length of stem.

The Sweet Pea is an annual which benefits particularly from an autumn sowing under cloches. The sowing is done directly into the flowering position during the very early days of October. On ground brought into good heart by being well prepared and trenched, and well enriched with decayed manure and bone meal, the plants are bound to do well. For general cutting purposes, and where the plants are being grown on the bush system, the seed can be broadcast in flat-bottomed trenches finally thinning the seedlings to 2 in. apart. The cloches are removed at the beginning of April when the plants are sturdy.

Although biennials, Brompton Stocks will benefit by cloche protection, the seed being sown in trays during July. The young plants are put under clothes in September, spacing them 8 or 9 in. apart and making two rows to the standard-size cloche. In the spring the plants may have grown tall, in which case it will be necessary to use elevators for extra height. The white varieties and the early pink, ‘Beauty of Nice’, are particularly useful for indoor decoration.

With clothes the subjects mentioned, together with gypsophila, eschscholtzia, sweet sultan and Saponaria vaccaria, will all produce flowers which will be ready for gathering in May.

The sowing of seeds in the greenhouse has many advantages. As far as plants intended for outdoor culture are concerned, it means that they are ready earlier than from seed sown in the open ground.

Wooden boxes, trays, seed-pans or flower-pots may all be used for sowing purposes. They must be clean and provided with drainage material at the bottom. New receptacles should be soaked for some hours before use. Crocks should be placed curved surface downwards, so that the drainage holes are not blocked by the compost and excessive moisture can drain away. With seed-trays, the gap between the bottom

boards should be covered with crocks, and in all cases a layer of leaf mould placed over the crocks is helpful.

There are a number of good soil mixtures available, the John Innes seed compost being used by many gardeners. Whatever mixture is used should be able to hold moisture, as some seeds should not be watered until they have actually germinated. The compost should be nicely moist, but not wet. Work it down in the corners and along the edges of the boxes, and afterwards level it off and press it down with a wooden block or presser, so that the surface of the soil is I in. from the top.

Sow very thinly. With fine seed such as begonias, calceolarias and gloxinias, it is a good plan to mix the seeds with silver sand, as this helps towards more even distribution. Crowded seedlings are liable to be attacked by ‘damping-off’ _disease. Really good-sized seed can be sown individually, thus reducing the thinning-out requirements. A very light covering of soil is required, depending on the size of the seed. The smallest need only be pressed into the compost.

After sowing, a very light sprinkling should be applied; the later waterings should be done by placing the boxes or pots in shallow water, so that the moisture seeps through the soil.

Apart from moisture, seeds need warmth, and it is wise to place a sheet of glass covered with paper over the receptacles. Remove the paper as soon as growth is seen, but leave the glass for a day or two, turning it occasionally. If the surface soil dries out, a very light syringing of water can be given. Subsequently prick off the seedlings to their boxes or pots, continuing this until they reach their final receptacles. It is wise to keep to small pots in the early stages, otherwise excessive root and leaf-growth is made but few flowers are produced.

For the early January sowings, a temperature of 65–7o0 will enable a start to be made with such plants as amaryllis, freesias, gloxinias, salvias and streptocarpus.

Ferns are raised from spores which can be sown in boxes of fine compost, being merely pressed into the soil and covered with glass and paper until growth is seen. These like rather more moisture than other plants.

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