For gardeners keen to get ahead of the season, starting seeds indoors provides a perfect solution to beat the lingering winter cold. According to experts, you don't need a vast amount of space; a simple, dedicated windowsill can be the ideal nursery for your future plants. By cultivating vegetables, herbs, and flowers in late winter and spring, you can ensure they grow into strong, healthy specimens ready for transplanting outdoors when the warmer weather finally arrives.
The Benefits and Basics of Starting from Seed
Huw Richards, a popular YouTuber, best-selling author, and horticulturist, strongly advocates for growing from seed. His new book, How To Grow Food, co-authored with chef Sam Cooper, is set for release on 12 March 2026. Richards explains that sowing your own seeds offers greater variety and transparency compared to buying pre-started plants. "It’s like the difference between fast food and a home-cooked meal," he says. "When you grow from seed, you know exactly what has gone into your plants."
To begin, you will need a few key items: seed trays (with or without individual cells), high-quality peat-free multi-purpose compost, and your chosen seeds. For early sowing, a heated propagator or heat mats are highly recommended to aid germination. Useful extras include trays with ventilated lids, a fine mist sprayer for gentle watering, plant labels, and a waterproof marker.
Mastering the Three Essentials: Water, Heat, and Light
Richards, who is also a Gardena brand ambassador, identifies water, heat, and light as the three critical factors for success. "The most common error is overwatering," he warns. "Too much moisture causes seeds to rot. The compost should be damp, like a wrung-out sponge."
Early-sown edibles like chillies, aubergines, bell peppers, and tomatoes require additional warmth to germinate reliably. While some gardeners place trays in a warm airing cupboard until germination, Richards notes that any ambient warmth helps. He advises moving seedlings to a sunny windowsill at the first sign of sprouting to prevent them from becoming leggy.
For those limited to windowsill space while temperatures are still cool, investing in a heated propagator or roll-up heat mats is a smart move. Richards suggests starting chillies and aubergines in late February, with tomatoes following at the end of February. Starting tomatoes too early can lead to them outgrowing their pots long before they can be moved to a greenhouse or polytunnel in early May.
Flowers and Final Practical Tips
From February onwards, flower seeds such as calendula, cosmos, nigella, larkspur, and ammi majus can be sown. However, these heat-loving varieties also benefit from bottom heat for successful germination. If you prefer not to use heated accessories, it's best to wait until mid-spring when ambient temperatures are higher.
Richards offers several key sowing tips:
- Always use good quality, peat-free compost, ideally endorsed by the RHS or Soil Association.
- Dampen the compost before filling your trays, ensuring it is moist but not waterlogged.
- Follow the instructions on the seed packet for sowing depth and spacing.
- For larger seeds like broad beans, use deeper pots or cells to accommodate root growth.
- Rotate seed trays daily if on a south-facing windowsill to ensure even growth.
- Water seedlings with a fine spray as the compost dries out.
Once seedlings have developed three or four 'true' leaves (the leaves that appear after the initial seed leaves), they can be transplanted into slightly larger pots. When thinning out crowded seedlings, cut the weakest one at the base instead of pulling it, to avoid damaging the roots of its neighbour.
Finally, Richards urges gardeners to be patient. "My biggest sowing month is actually May," he reveals. "Plants catch up. You can still sow tomatoes in early April and get a fantastic crop. There's loads of time."
