Saving & Sowing Tomato Seeds
Many people choose to grow tomatoes from small plants purchased inexpensively at the local garden center. There’s absolutely nothing wrong with doing so and it makes growing tomatoes all the more easier for the home producer. However, if you choose to go this route you’ll likely be limited to growing just a few of the most popular commercial strains instead of being able to choose from the hundreds (maybe thousands) of varieties available.
Growing tomatoes from seed isn’t difficult but you do need to start them early, especially if you live in cool-to-temperate regions. On the Isle of Man it’s practically impossible to grow them outdoors but nurturing them in greenhouses, polytunnels, and warm windows is both popular and worthwhile. Nothing beats the taste of a sweet and juicy home-grown tomato! Also, growing ‘from scratch’ is a lovely way to see the whole process of seed transforming into plant and then flowers developing into fruit.
For me, growing tomatoes begins in late January to February when I sow the seeds for my conservatory-grown plants. If you sow the same time as I do you be picking your first crop weeks before anyone else and will also get a bit of a gardening fix before the real season of sowing begins. If you’re in the same climate as I am but will be planting into unheated greenhouses, wait just a month or two later though. If you rush things along then by the time the plants are mature, it might still be too cold for you to plant them out.
To start your seeds this early you’ll need to do it in a warm place with plenty of light. Bottom heat is preferable and if you don’t have a propagator then setting the tray of seeds near a radiator works well too – just make sure it isn’t too hot and that the compost stays moist. Popping the tray into a clear plastic bag also helps in both retaining heat and moisture. Use multipurpose or seed-starting compost and the rule of thumb in sowing is to cover the seeds with soil twice the depth of the seed itself. So if the seed is 3mm in length (the size of a tomato seed) then cover it with 6mm of soil. Tomato seeds germinate best at around 70-80°F and in this temperature you can expect to see green shoots within 6-8 days.
The seeds you start with can come from a packet but it’s always fun to save a few from the last year and grow them on again. If you grow more than one variety in the same area the seeds might not grow true to their original (due to cross pollination) but who knows, you could end up with a fantastic new variety.
When the time comes to start your seeds off use a pair of scissors and cut a square off your paper towel. This way you can save some of the seeds for another time, which is a good idea in case you have a real winner of a variety and want to grow it again. It’s amazing to think that when stored at room temperature, tomato seeds can still be highly viable even after ten to fifteen years.
Spreading your seeds out when you dry them helps in the growing stage since it staggers the space between seedlings. But if they grow in thickly, don’t worry, they can be thinned out without too much fuss – see my post on how to do it at this link. You’ll want to transplant your seedlings into individual modules when two true leaves have appeared.
If you’d like further information on how to grow your tomatoes from this stage on, I’d recommend that you have a look at the RHS website for further instruction. You’ll need to consider varying factors depending on your situation, climate, soil, and variety, and there’s plenty of information to be had at this link including a short video.