11 Apr 2008 - 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.

 

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

 

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 more easily controlled.

 

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 are likely to 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. Click here to view 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 due to being 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 seedling. Bean and pea seeds sown directly in the ground are often foraged by mice.  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 seed in pots, cells or seed trays in the greenhouse. Quarter size seed trays are useful as they take up a relatively small space in the greenhouse or propagator and also 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 though as the saving on seed is offset by the need to buy compost etc. It is important however, to have as high a percentage successful germination as possible if there is only a sprinkling of seed in a packet.  When sowing into pots or trays rather than into open ground it is easier to control the number of seed 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 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. 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.

 

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 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.

 

Type of Seed	Preferred Method of Raising Plants
Aubergine	Seed tray then into pots
Broad Bean	Sown 2 seed to a pot
French Bean	Sown 2 seed to a pot
Runner Bean	Sown 2 seed to a pot
Beetroot	Sow 2 seeds into multi-cells
Broccoli	Seed tray then into pots
Brussels Sprout	Seed tray then into pots
Cabbage	Seed tray then into pots
Carrot	Sown directly into ground into a drill of compost
Cauliflower	Seed tray then into pots
Celery	Seeds tray then into multi-cell system
Courgette	Seed tray then into pots
Cucumber	Seed tray then into pots
Kale	Seed tray then into pots
Lettuce & Salad Leaves	Seeds tray then into multi-cell system
Leeks	Seeds tray then into multi-cell system
Marrow	Sown 2 seed to a pot
Melon	Sown 2 seed to a pot
Spring Onion	Early crop in multi-cell system to maturity. Rest sown directly into ground
Parsnip	Sown directly into ground
Peas	Sown 3 seed to a pot
Potato	Chitted and planted directly into ground
Pumpkin	Sown 2 seed to a pot
Radish	Early crop in multi-cell system to maturity. Rest sown directly into ground
Spinach	Seed tray then into pots
Squash	Sown 2 seed to a pot
Swede	Sow 2 seeds into multi-cells
Sweet Corn	Seed tray then into pots
Tomato	Seed tray then into pots

 

 

Click here for some products that we regularly use.