When is the best time to sow seeds?

Blog - sowing

One of the things that always gets me through the winter months is seed purchasing; the thrill and anticipation of a new gardening season beginning.

With last year’s mistakes forgotten, this year’s plans and ambitions are made. I trawl through the seed catalogues getting (some may think sadly) very excited at the productive pictures that inspire me to want to grow all sorts of new weird and wonderful plants that I haven’t tried before.


Once the carefully packaged seed packets arrive, I admire them, hold them in my hand, feel the excitement for the plant that this tiny seed is going to become. Then I store them carefully in my seed box in order of sowing month, close the lid and it’s at that moment that the worry and doubts start to creep in.

Blog - seed packs

Make hay while the sun shines

A little scroll on social media shows me picture after picture of other happy horticulturalists with brimming trays of seductive seedlings ready for pricking out. After a long winter of clean fingernails I’m itching to get my hands in the soil. Then of course the gardening programs begin on television, enthusiasm takes over and all of these things combined, lead me to embark on an eager planting frenzy when perhaps the sowing conditions aren’t quite right.

There is also the “Fool’s spring” to consider, those glorious few days of summer sunshine that appear for a few days in March that get us reaching for the sun cream and short sleeved t-shirts. Many a seed is planted a little too early and then the sun goes away and the cold nights return leaving them struggling to germinate.

So, what are the right sowing conditions?

Blog - seedlings

A lot will depend on your set up. Some people choose heat mats, heated propagators or are fortunate enough to have a heated polytunnel or greenhouse. Having this kind of equipment or set up means that you can have seedlings ready early which is useful for growing plants that thrive in the warmth such as tomatoes, chillies and aubergines. Of course once your seedlings are through you will need a warm place to bring them on or keep them until the soil outside has warmed up to 15-20 degrees, such as a warm greenhouse or polytunnel. Plants that like the warm will need warmth to continue to develop once germinated.

If you don’t have the help of artificial heat don’t despair, most veg and flower seeds can be started off on a sunny windowsill in spring close to the time when the ground will be ready for them. Seeds germinate best in warm and damp conditions. With this in mind covering your seeds with a plastic cover (which can be specifically bought) or using something as simple as an old transparent food container or even a piece of clingfilm will help trap warmth and damp, assisting germination. Once your seeds have germinated you need to remove the covers and allow them access to the sun so they can photosynthesize and grow bigger and stronger. 

Sowing directly

Sowing seeds directly into the ground once it is warm enough, around 15-20 degrees (follow individual seed packet instructions), is a simple option. Sowing directly is more efficient way to garden, you sow later but avoid having to prick out seedlings and pot on, saving not only time but also space and resources too. No need for mountains of shop bought or home produced compost and plant pots. However, bear in mind the composition of your soil. If you are looking to get the most from your seeds you could consider topping up your beds with a task-specific topsoil that has been blended to contain the right nutrient levels to achieve successful healthy plants. If you are short of outdoor covered spaces or windowsill space then this is a fantastic time saving option!


Timing also depends on which part of the UK you live in. Those of us in the milder south and east are able to direct sow sooner than those in the north or west of the country where the climate takes slightly longer to warm up. According to the Met office website “places in the east and south of the UK tend to be drier, warmer, sunnier and less windy than those further west and north. Also, these favourable weather conditions usually occur more often in the spring and summer than in autumn and winter.” This means those living in the north and west of the country need to wait longer than people living in the south and east to direct sow their seeds or they may choose to use covered spaces or sunny windowsills to start seed germination ready for when the weather conditions are right for planting out.

"If one way be better than another, that you may be sure is nature's way." Aristotle

Going back to the days when I worked full time as a primary school teacher, I would get to the Easter holidays and only then would my thoughts turn to the garden. I’d generally have one day of the holidays, with the children, in the garden. On that one day, we’d plant all our seeds, regardless of packet recommendations because we didn’t have time to read or we’d missed the time frame for following them. In all honesty everything grew fine, we always had an abundance of courgettes, lettuces, tomatoes and potatoes without a fraction of the worry. 

So I guess the lesson here is sow what you can and when can. The best trick being: follow mother nature, let her warmth guide you.

Guest Author: Nicky Sharp
Nicky is a green-fingered mum of three who until recently was a self-taught gardener. Having left her teaching career to support her young family, she has now been able to pursue her passion for horticulture, recently embarking on an RHS course to enhance her expertise.