In the UK in January, daylight hours are still very short, outside temperatures low and likely to get lower in February. The best advice for seed sowing for the majority of people is to wait until March to sow the seeds of most plants when day light hours will be longer and outdoor weather starting to get warmer.
Benefits of waiting include stronger, healthier plants in the improved conditions, they’re less likely to get etiolated (stretch toward the light) or succumb to damping off (a variety of seedling killing problems), and less time hogging window ledges or greenhouse shelf space.
That said, there are some exceptions and even some plants that will benefit from being sown now. So, if you have itchy sowing fingers, read on my friend…
Seeds you can sow now in January
- Chillis, peppers and aubergines – a bunch of plants that benefit from being sown between January and February because they can be slow to germinate and slow to crop. The earlier you sow, the better. They must be sown inside in the warm, and even those on a bright window ledge will need a bottom heated propagator, in a greenhouse they’ll need this and the greenhouse to be heated to a minimum of 15 – 18C. Indoors on window ledges, they will benefit from a grow lamp for additional light set to summer daylight time of 14 hours.
- Sweetpeas – if you haven’t sown them yet, you can actually wait until spring and they’ll just flower a bit later, which can be no bad thing as they’ll go on to flower longer in summer too. However, I usually sow mine in January to grow strong root systems now. Germinating them inside in a little warmth and then moving outside as soon as they’re shooting above the compost. Depending on where you are in the country, you can either leave outside in a sheltered spot if in a mild area, or place into a cold frame or unheated greenhouse in warmer areas.
- Microgreens and shoots – these can be sown at anytime of year on a windowsill including the depths of winter, though they still need as much sunlight as you can give them. Try things like pea shoots, basil, kale, coriander, amaranthus, cress, mustards and many others.
- Onions – many wait until February – I usually sow mine in early Feb – but can be sown now if you need to. I prefer growing onions from seed over starting them from sets and it’s very easy. Sowing early inside gives them extra time to bulk up and form bulbs. Thankfully, although they need a lot of light, they won’t really get etiolated in the same way as plants with stems, though their leaves will still grow longer to stretch for light initially.
- Ornamental grasses: I find these can really be sown at any time of the year inside. Spring is going to be best but I’ve sown many grasses in December or January and because they don’t have stems, they don’t suffer like stemmed plants from lack of light. Though of course, almost all grasses do need a lot of sunlight – as much as you can give them. Then in spring off they’ll romp.
- Shade loving ornamentals: things like Coleus can be started indoors now, though really, I don’t advise it. One year I sowed loads of coleus seeds in January because I didn’t want to wait, they looked beautiful as they germinated and then all succumbed to damping off and died. In following years I waited until early March and they all grew much faster and more strongly with no problems.
- Hardy seeds that need stratifying – often seed packets will advise to stratify seeds in the fridge but the natural fridge works too: outside, if it’s cold enough. You can sow these types of hardy seeds into pots or direct into the ground now if you like but do mark them as they’ll take a while to germinate as spring’s warm weather is still a way off. Other regular hardy plants that don’t need stratifying, well, you can try sowing them too but personally I’d wait as better they germinate quickly in warm weather than risk rotting or being eaten. They’ll probably be fine but why be impatient for the sake of a month or two.
Greenhouses, conservatories and grow lights
Obviously, all rules can be thrown out the window if you can provide different environmental conditions for plants artificially. If you can keep temperatures consistently high and provide additional light from grow lights, you can basically create spring or summer conditions. In this case, try growing whatever you like now!
A note on tomatoes
Some people recommend sowing and growing tomatoes now in January, but I would hold off unless you are sure you have all of the equipment ready to keep them happy over the next few months.
Tomatoes will happily grow in warm environments but without extra light will become etiolated (leggy) which for tomatoes isn’t a huge problem as you can always pot them up lower in compost, burying them deeper to support the stem. This encourages more roots to grow.
However, I wouldn’t personally bother sowing them until at least late February myself because without a greenhouse to move them into, you’ll just have large plants taking up loads of space for months until you can move them on elsewhere. They can’t go outside until late May to June for most of the country and you probably wouldn’t risk moving them into an unheated greenhouse until that time or close to it.