transplanting

Direct Sowing Versus Transplanting

The beginning of spring is the start of what can become a frantic seed sowing season. Most of us will have lots of successes and failures but hopefully the failures will reduce as we learn from experience. Each of us will develop a system that works for us. The following is what we have found works for us.

For several reasons, we prefer to grow our seeds under cover rather than setting them to take their chance in the open ground.

One reason is that seeds can be sown even when the outdoor weather conditions are not really favourable. For instance when the weather is very wet and cold, the soil conditions just would not suit the seeds. Watering is also more easily controlled.

The soil on our allotment is heavy clay which is not the best medium in which to start off seeds.

During times of little rainfall you can ensure that pot and tray sown seeds have adequate water. During times of excessive rainfall ground sown seeds can be washed away.

There are of course some pitfalls that have to be avoided when starting seeds off indoors. On warm sunny days (yes we do get them!) trays and pots can dry out really quickly. On such days you need to ensure that the greenhouse is well-ventilated. Where weather conditions change during the course of the day this can be difficult so it may be wise to installed automatic opening devices to vents and/or louvres.

If your greenhouse is unheated it may also be necessary to provide some overnight protection to tender plants and seedlings. This could be a covering of fleece just draped over the trays or pots.

Plants sown indoors are given a good start as the seedlings, not only are grown in more favourable conditions but they don’t have competition from weeds. When plants are transplanted into the ground they are strong and healthy and are less likely to be devastated by pests and disease. Slugs often enthusiastically mow off whole rows of young seedlings. Bean and pea seeds sown directly in the ground are often foraged by mice. However, seeds sown inside can also fall foul to the same pests as outside so some check needs to be kept on slugs and mouse activity and necessary steps taken to protect seedlings and seeds.

We sow most of our seeds in pots, cells or seed trays in the greenhouse. Quarter and half size seed trays are useful as they take up a relatively small space especially if using a propagator but they generally have plenty of space for the amount of seeds needed for any given variety or type of plant.

Sowing seed into trays and pots also makes better use of the seed as germination seems more successful and so less seed is wasted. This can be an important factor as many packets of hybrid seeds contain very few expensive seeds. Cost cannot really be the driving force as the saving on seed is offset by the need to buy compost etc. If there is only a sprinkling of seed in a packet it is important however, to have as high a percentage successful germination as possible.

When sowing into pots or trays rather than into open ground it is easier to control the number of seeds sown. Sowing directly into the soil often results in seed germinating in clumps and gaps being left in the row.

Cells are useful for seedlings that do not respond well to being pricked out such as beetroot, swede and turnip. The larger cell trays also take up far less room than the equivalent number and size of plant pots and are easier to carry and transport. Alternatively you can buy trays of plant pots. These consist of a tray which plant pots slot in to. Some trays are designed to be used in conjunction with capillary matting. Nurseries often use polystyrene trays into which plant pots are slotted – we have acquired some of these when buying plants over the years and they are also useful for keeping plants pots together.

After sowing seed we usually apply a covering of vermiculite or perlite to the surface of the compost. This tends to cut down on the algal growth that can sometimes occur and inhibit germination, especially if seeds take a long time to germinate. If the seed is very small or if it needs light in order to germinate then the seeds are covered with a layer of vermiculite rather than leaving them totally exposed. This allows light through to the seed.

Seed sown in trays need to be pricked out when they are large enough to handle, usually when the first pair of true leaves have grown. When doing this, so as not to damage the root, gently tease the seedling from the soil using a pencil or similar object. Handle the seed by its seed leaf and not a true leaf or stem as this can damage the seedling and leave it prone to disease. Seed leaves are the first leaves that grow after germination and are often a different shape from the plant’s true leaf. For more details about pricking out click here.

Growing seedlings need plenty of light or they become drawn and leggy, so after germination they need to be transferred to a position that is as well lit as soon as possible.

Plants grown in a greenhouse require hardening off before being transplanted outdoors. Young plants can be hardened off by placing them in a cold frame or sheltered outdoor position for a few days. Hardening off alleviates some of the shock to the plant of being moved from a cosy position into exposed open ground.

The following table shows how we think that you will get best value from expensive seeds. Most seed will last more than one year. Parsnip seed is exception and we use fresh seed each year.

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