3 RHS-Approved Indoor Sowing Tips

The dormant season is in full throw and at this time of year there are often few jobs to do on the vegetable plot. Sowing seed indoors however is a great way to get long season crops, such as chillies and leeks, off to a great start.

1) A heated propagator is an ideal way to start seeds off early, however a clear plastic freezer bag over the top of a pot will achieve the same results, albeit a little slower. Once germinated, seeds can be removed from the propagator and placed on a warm, light windowsill to grow on.

2) Chilli seeds are small and therefore can be sown in trays on the surface of good quality flattened seed compost. Once sown, cover seeds with a dusting of vermiculite or fine compost. Ideal germination temperatures range between 27°C-32°C, however seeds will still germinate well at 21°C. Prick out seedlings when about 2.5cm tall individually into 10cm pots, ensuring you handle the seedlings by the leaves so as to not damage the stems. Make sure the seedlings are planted deep with their leaves just above the surface which will ensure a good root system develops. Grow on seedlings in a warm environment with plenty of light.

3) Leek seeds are larger and therefore need sowing at about 1cm depth. This veg can be left undisturbed in the same pot until time for planting out. Sow eight leek seeds per 10cm pot ensuring pots are kept between 16°C–21°C and moist but not waterlogged. Thin seedlings out to four of the strongest once 3cm tall. Use larger pots if more than four seedlings are required, however ensure that each seedling is thinned to about 2.5cm apart. Once germinated, ensure leeks are placed in a light position with a temperature range preferably between 13°C to 18°C.

This piece was written by RHS horticulturalist Francesco Ponziani who works at Harlow Carr. This piece also featured in the February issue of Grow Your Own magazine.

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