Sowing seeds on open ground

Sowing seeds in open ground
Image: shutterstock

Sowing seeds directly into the ground where they are to grow is a quick and easy way to raise plants, flowers and vegetables. With no potting on, hardening off or root disturbance, some plants actually prefer this hassle-free method. Here, Richard Bird discusses the pros and cons of direct sowing seeds in open ground rather than using seed trays and pots.

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The benefits of direct sowing

When authors refer to growing from seed, it's usually assumed that the seed will be sown in pans, pots or trays. There are obviously many advantages to this. In particular one has much greater control over the growing medium with regard to its composition, water retentiveness and the amount of heat, water, fertiliser and light that it receives.

Growing seed outside in the open ground is more hazardous as it's not so easy to control these factors. Yet gardeners, and more obviously farmers, have for generations used this method. It seems safe to assume that this would have been the earliest method of sowing seed.

There are many plants that produce seed that germinates very readily and does not need the cossetted conditions of the pan. This saves a lot of time and energy as well as releasing hard-pressed space in propagators and frames. Admittedly an eye must be kept on the weather conditions and water must be provided if necessary, but the vast volume of soil does not dry out as readily as a pot, and generally the seed can be left to germinate without any attention at all. Many plants are sown in situ so that there is no pricking out or potting on to do, which always causes a check in the plant's growth. Another advantage is that there's no hardening off (a very necessary process that I hate) to bother with, which again can cause a check.

Direct sowing vegetable seeds

Direct sow beetroot seeds for quick and easy crops
Image: Beetroot 'Chioggia' (Globe) seeds from T&M

The most obvious choice of candidates for this kind of sowing is, of course, vegetables. Most of these will germinate happily outside in the open soil. The only time it's worth sowing them in pots is early in the year so that the growing plants can be planted outside immediately after the last frosts (or earlier if they are kept under cloches). This will inevitably lead to an earlier cropping.

Another reason for growing in pots may be to produce mature plants that can be used immediately as replacement crops when a piece of ground is cleared of one that is finished. These reasons aside, the majority of vegetables are sown direct.

Direct sowing flower seeds, plants and shrubs

Direct sow swathes of cornflower seeds for maximum impact
Image: Cornflower 'Jubilee Gem' seeds from T&M

In the flower garden a lot of annuals can be sown direct in the soil, particularly the hardy annuals some of which, like cornflowers, can be sown in the autumn. This has the advantage that the resulting plants flower much earlier in the year, giving them potentially a longer flowering season.

The tender annuals must, of course, be sown in late spring so that they don't appear before the frosts have passed. Here it can be advantageous to sow in pots, as mature plants can be produced ready for planting out by about the same time as one would sow outside.

As well as annuals, a lot of perennials (particularly the larger stronger growing ones) can be grown outside including herbaceous plants like delphiniums, lupins, hollyhocks and so on. These would be sown in a reserve bed or vegetable garden, and grown there until they were big enough to transplant into their permanent positions. The main advantage of this is that a lot of plants can be grown with the minimum of trouble. To prick out and pot on, say, a couple of hundred of a single species just to find out if there are any good coloured forms that are worth growing on takes a lot of effort, not to mention space and compost, and can be more easily achieved in the open ground.

Trees and shrubs which are needed in quantity, particularly for hedging, can be sown outside, which has the advantage of allowing them a natural stratification as they're open to the elements.

How to prepare the soil for direct sowing

One of the first requirements for sowing outside is a good seed bed. This can be a separate nursery bed or any part of the garden where you want to sow the seed in situ. The ground should be well prepared, with all weeds removed. Organic material should be incorporated into the soil as it is dug. The prime consideration is a fine tilth, something that gardeners have sweated over for generations. A fine tilth means that the dug soil must be broken down into fine particles, not quite as fine as dust, but as near as can be achieved with a rake.

If the ground is dry, the plot should be well watered several hours before sowing takes place to allow the soil to take up moisture.

How to broadcast-sow seeds

Essentially there are two ways of sowing outside: by broadcasting or in drills. The former method was adopted by farmers before the advent of mechanised seed drills. It simply involves scattering seed over the prepared soil and lightly raking it in, and is most commonly used for sowing grass seed. It's also used for sowing annuals over a particular area in a border. The difficulty with this method is in producing an even spread of seed. Unfortunately most of us use this method so seldom that we do not acquire skill in its execution. One way to help is to lay out a grid on the soil before applying a prescribed amount of seed to each square (a handful, for example, or a more precisely measured amount if necessary). Some seed (such as grass seed) can be easily seen when it is cast, whereas others benefit by being mixed with a light or dark sand which will give an indication of the evenness of the spread when both are scattered together.

The best way to use seed drills

Parsnips can be station sown in seed drills
Image: Parsnip 'Warrior' F1 Hybrid seeds from T&M

The other method, most widely adopted by gardeners, is to sow in drills or rows. Here it's a question of marking out a row with a piece of string and then inscribing a shallow drill with the corner of a hoe or a sharp stick. The seed is sown thinly in this drill and then a thin layer of soil is drawn back over the row. It's essential to label the row, partly to help with weeding, and partly so that you know what the row contains.

Some seed, like parsnips which will be thinned out to a reasonable distance apart, say 9in (23cm), can be station sown. This entails sowing three seeds every nine inches leaving a gap between each group. When the seed germinates, two are removed to leave the strongest. With varieties that are slow to grow, again like parsnips, it's possible to grow a faster germinating plant like radishes in the gaps between the groups. This not only allows the gardener to get the maximum from his space, but also gives a good indication of where the rows lie, making it easier to hoe between them without accidentally disturbing the slower seed.

If, as is often the case, the soil is heavy and very difficult to break down, it's possible to draw out a deeper row and fill it with a layer of compost, either from the compost heap or potting compost. The seeds can be sown on this and then lightly covered with a further layer. This technique can also be applied in areas that are dry, as this compost will more readily hold moisture and help the seed germinate.

How to care for direct sown seeds

One of the main problems in the open is keeping household pets and birds from rolling in the fine soil. Disturbance of this kind can be avoided by covering the seed bed with netting, or by temporarily laying down a number of pea sticks on their side over the drills.

The other problem is moisture. Since the seed is lying just beneath the surface it's in an area that dries out very quickly. Keep an eye on it, and water with a fine rose watering-can if it becomes parched.

Earlier crops can be achieved by covering a seed row with a glass or polythene cloche. It also enables more tender plants to be sown before the risk of frost has completely passed. There are, however, many flowering plants, both annual and perennial, and vegetables that can be sown in the autumn and which will happily overwinter in the open.

Looking for more information and advice? Read our horticultural team's tips on how to sow seeds successfully and find out what to sow and grow each month in our helpful guides.

About the author:

Richard Bird is an author of a number of books covering different aspects of gardening.

Source of article
Growing From Seed - Autumn 1990 Vol. 4 Number 4
© The Seed Raising Journal from Thompson & Morgan