Germination
If seeds are to germinate quickly, and seedlings grow vigorously, they must be started in the right conditions.
Temperature—this is the first thing to consider.Details of seed temperature needs can usually be found on the seed packet or in a gardening book. Most seeds germinate better in warmth, but there are some that need cold in order to germinate. Where warmth is needed it is best to aim for a few degrees above the minimum figures given on the packet.
Moisture—seeds need to be moist to germinate and grow. Too much moisture will cool them down, drive out air and encourage fungal diseases. Avoid overwatering pots and trays.
Light—many seeds will germinate in either dark or light conditions. However, some do much better in light, such as Busy Lizzies. Others germinate better in the dark, such as pansies. Once germinated, seedlings do not need high temperatures, but they still need warmth and good light or they will become pale and straggly. Draughts are very dangerous to newly germinated seedlings. Seedlings need protection against frosts if they are to make good growth. When sowing seed outdoors, wait until the outside temperature is at the minimum stated for at least a week.
Time before flowering or cropping.
Many slow maturing crops, such as summer flowering geranium, and tomatoes, can only succeed if started indoors—if you wait until the weather outside is suitable, there is insufficient time for the plants to reach maturity.
Transplanting
The advantages of transplanting are that plants can be started indoors then planted out as strong transplants. It gives them a head start. It also means that other quick growing crops such as radish can be grown temporarily in the space set aside for the seedlings. Some plants are happy to be transplanted. Others such as carrots and parsnips, do not like root disturbance. Grow these in their final position directly from seed . Growing in modules (divided trays) helps avoid root disturbance.
Avoiding pests and diseases
Sowing indoors may give seedlings protection against pests and diseases while they are most vulnerable. Drier conditions reduce the chance of fungal infections.
Growing from seed - outdoors
Good soil preparation is essential when growing from seed. Drainage and fertility need to be right, whatever you are growing. The top inch of soil needs special attention. The ‘tilth’ is the condition of the soil surface when ready for seed sowing. A particularly fine tilth is needed for small seeds such as carrots and onions. To achieve this rake the soil, break up any lumps, then even the soil surface.
Spring sowing—Don’t sow too early as cold, wet soil will rot the seeds. A good time to start sowing is when weeds begin to grow. For earlier sowing cover with clear polythene and grass for a week or two to warm up the soil. Remove when ready to sow.
Summer sowing—If soil temperatures are too high for certain crops, such as lettuce, water the ground well and cover with sacking or other shading material to cool it down before sowing.
Autumn sowing—The soil is still warm so this is a good time to sow hardy annuals to overwinter. Try Californian poppies and nasturiums. This gives them a head start in spring. If sowing in a row, you need to create a drill - a shallow trench. You can also broadcast sow, which means sprinkling the seeds evenly across the plot. If the soil is dry, water the bottom of the drill before sowing. If you water after sowing, a hard crust of soil (a pan) can form. It can stop seeds emerging. Details of spacings and how deep to sow the seeds will be on the seed packets. Do not sow too thickly. This will waste seed and result in overcrowding. Once sown, cover the seeds with fine soil and press it down with the back of the rake. Seed and soil must make good contact.
Growing from seed - indoors
The traditional method of starting off seeds indoors is to sow them in a single pot or in trays.
Once the seedlings have emerged they are pricked out into trays or individual pots. The modern alternative is to sow directly into modules (trays divided into small sections). Thinning the seedlings is unnecessary and seedlings do not suffer from being moved. Seed modules avoid overcrowding, so there is less risk of disease.
Potting Compost—it is preferable to use organic potting compost for sowing, but if this can’t
be found then use a peat-free mix. You can make your own potting compost.
Sowing seeds:
- Fill the pot with potting compost to 2cm below the brim.
- Firm the surface with something flat, like the bottom of another pot, and sow the seeds thinly.
- Cover large seeds with sieved compost to a depth no greater than twice the size of the seed. Very small seeds should be left uncovered.
- Stand the pot in a bowl of water and allow the water to soak up from below. Do not saturate, the compost should be moist. Drain excess water.
- Cover the pot with clingfilm to stop moisture escaping.
- Place the pot in a warm, light place.
- As soon as the seeds germinate take off the cover.
