Sowing vegetables and flowers - when, where and how to care for them

10 tips for sowing seeds and growing plants on your windowsill. From March you can start growing your first flowers and plants indoors. These tips will help you grow them successfully.

Every spring there is a wide range of young plants available to buy. However, amateur gardeners who want to grow certain varieties in their garden often cannot find them in the shops and prefer to grow their own young plants. It is also much cheaper to grow your own seedlings on your windowsill or in a greenhouse. Another advantage of starting seedlings is that it makes the gardening season more enjoyable.

If you want to start your plants indoors, here are the answers to the 10 most important questions about starting seedlings indoors.

1. Which plants are suitable for windowsill starting?

Our growing season is too short for many warmth-seeking vegetables to be ready for harvest by autumn. However, the flowering period of many flowers can be extended by starting them indoors.

Examples of plants that are suitable for pre-cultivation include:

• Vegetables: tomatoes, aubergines, cucumbers, broccoli, celery, iceberg lettuce, pumpkins, courgettes, cucumbers, peppers, chillies.
• Flowers: sweet pea, morning glory, bell vine, love-in-a-mist, stock, snapdragon, gypsophila, petunia, black-eyed susan, zinnia.

2. When to start sowing?

Don’t start sowing on the windowsill before March is an accepted rule of thumb. This is because the sun will not be able to give the plants enough light before then, causing them to ‘go to seed’. This means that they will grow into thin, weak plants with long stems. You can start sowing earlier under the light of a plant lamp.

3. What type of soil should I use for pre-growing?

Seed soil is the best choice for pre-grown plants. It contains few nutrients so that the young plants develop strong roots. Seed soil is also sterilised, so there are no pathogens or fungal spores in it.

Tip: Use regular potting soil for the bottom half of the planter and seed-starting soil for the top half.

4. What kind of planter should I use for windowsill sowing?

There are different types of planters that are suitable for sowing seeds. It is important to fill the pot with soil only about an inch below the rim. This leaves enough space and air to cover the pots with glass or plastic.

• Seed trays: Trays are ideal for sowing fine seeds. You can select the strongest seedlings and transplant them into pots.
• Multi-pot or quick pot trays: A good idea for hobby gardeners with plenty of space and a desire to grow lots of plants. Quick pot trays, which are also used in professional horticulture, are made up of many small pots that form a tray. You can sow seeds in the pots and repot the seedlings with their small root balls.
• Egg boxes: A cheap and small version of multi-pot trays. Fill the recesses with soil and place one or two seeds in each compartment. Egg cartons are best for coarse seeds. You can plant the seedlings in the soil with the egg carton as it will rot away.
• Small flower pots: Good for relatively coarse seeds that will germinate reliably. Advantage: You can fit a pot in even the narrowest windowsill. Put only three seeds in a pot. The seedlings can then be transplanted to larger pots without pricking.
• Toilet paper rolls: Fill toilet paper rolls with soil and germinate just a few seeds. Then plant the seedlings in the roll directly in the bed. This method is particularly suitable for plants that develop deep tap roots, such as peas or sugar snap peas.
• Peat pots: The most convenient way to start plants. Simply sow up to three seeds on the substrate and then transplant the seedlings into larger pots or directly into the ground. Use only peat-free coconut fibre pots.

Tip: Very fine seeds can be difficult to spread evenly. Mix them with fine quartz sand or spread them over the seed tray using a slightly coarser sieve or salt shaker.

5. Sowing depth: how deep should I sow?

The rule of thumb is to plant seeds as deep as they are large. However, it is better to know whether the seeds are light or dark germinating.

Light-germinating seeds, such as dill, celery and snapdragon, should be covered with little or no soil. Dark germinating seeds such as pumpkins, sweet corn, lupins and hollyhocks need to be at least one centimetre deep in the soil.

Always press the soil around the seeds firmly so that the seeds are in good contact with the soil.

Tip: Cover light sowing trays with damp newspaper. This will prevent the seeds from drying out and being washed away when you water them.

6. How much watering?

The soil should always be moist, but not wet. It is best to water the seeds and seedlings with a spray bottle.

7. Where should the seed trays and seedlings be placed?

The seed trays should be placed on a windowsill where they get as much light as possible.

8. Do I need to cover the seeds and seedlings?

Covering is definitely recommended as the plants need a fairly high level of humidity.
The easiest way is to sow the seeds in a **greenhouse** with a suitable cover. You can also cover the seeds with foil, plastic bags, glass jars or halved PET bottles. You will need to air the area once a day to prevent mould. As the plants get bigger, cover the pots for only a few hours.

9. When do I need to pinch out the seeds?

Usually the small plants are too close together. Therefore the seedlings need to be pricked out, i.e. they need to be planted further apart. The right time to do this is when the young plants have developed at least two sets of leaves.

10. When is the right time to repot?

Young plants in pots should not be repotted until they are strong enough. This is usually when they have reached a height of 10 to 15 cm.