Tomatoes are a great greenhouse favourite and a welcome addition to any salad. There’s nothing quite like the taste of ones you’ve grow yourself, but although tomatoes are so popular, they aren’t without their potential pitfalls. So, to help you avoid some of the commonest problems, here are a selection of top tips to ease you on the way to a delicious crop.
Sowing the Seeds
Most problems at this stage occur either because the seeds are sown at the wrong time (too late is as bad as too early) or the growing conditions aren’t right.
- In a heated greenhouse, get an early harvest by sowing tomato seeds around Christmas and then planting them out in February or early March. Your crop should then be ready towards the end of May – but only try this if over-night temperatures never drop below 12 degrees C in your greenhouse.
- If you don’t have a heated greenhouse, you can still steal a march on things by up to a month by sowing in an electric propagator in March. There are plenty of kinds to choose from and different sizes and prices, so there’s something to suit everyone and they’ll be a real help with germinating all kinds of other seeds too, once your tomatoes are safely planted out.
- Early April is the usual time to sow if you’re not using any additional heating, planting them out towards the middle of May.
- Use good quality compost, dampened with tap water – not from the butt – to avoid problems with bacteria.
- Space your seeds out; it’s a fiddle to do, but give each one enough room to develop and then carefully cover the surface with a fine layer of compost..
- Use a cheap unheated propagator or cover the pots with cling film; it keeps the compost moist and helps reduce temperature fluctuation.
If you take a bit of care to produce good, strong plants at this stage, you should avoid a lot of the possible problems later on.
- Prick them out when the seed leaves are fully expanded; planting them deeply, so that much of the young stem is below the new compost level will encourage more root development, which adds stability for later on.
- Be careful when you handle your tomatoes; hold seedlings and larger plants by the leaves – never the stem – and don’t be rough with the roots. If two or more plants have entwined their roots in their pot or tray, tease them apart gently with a pencil and if you’re re-potting shop-bought plants, give them a good soak first to ease the root-ball out. Good roots are the foundation of a vigorous plant; avoid damaging them and you won’t set your new transplants back too much.
- Don’t overcrowd your plants. Grow bags are probably the most popular method of growing tomatoes, and it can encourage you to think about squeezing in a few extras. Some of the biggest overall yields can come from just a couple of plants per bag, so make your motto “better one plant too few, than one too many!”
- Make sure your supports are secure at the start. Whether you’re planning to use traditional canes or strings, or one of the more modern and high tech support systems available, take the time to ensure that everything is properly attached. There are few things worse than seeing a bumper crop, and all your hard work, ruined as the plant collapses under its own weight.
If you’ve successfully got as far as having a good set of plants and they’re all growing well, all you’ve got to do now is keep them that way!
- Take care with your watering. The trick is to keep it regular to avoid any problems and make sure that the compost remains properly damp – but not water-logged. This is especially important for grow bags, since if they once dry out, watering from the top may soak the surface but leave the middle – the crucial bit around your plants roots – still dry. It’s obviously crucial to take the time to get the watering right, particularly as the season progresses and the weather (hopefully) warms up.
- The special high potassium tomato fertilisers really are worth it; use one a couple of times a week and you’ll soon notice the difference.
- Don’t be too enthusiastic when it comes to pinching out the leaves – they’re all that’s feeding the growing fruit!
- Shade is vital when it gets really hot to avoid greenback – fruit that stays hard and un-ripened.
- Don’t try to set too many trusses of fruit; seven or eight per plant will give you the best compromise of quality and quantity.
Now all you need to do is wait – you’ll soon be enjoying the fruits of your labours, quite literally, in your salads.
When it comes to most things in the greenhouse, there’s one old proverb that applies, time and time again – “an ounce of prevention is worth a pound of cure” – and tomato growing is no exception. From seed to harvest, if you get the basics right, then unless you’re very unlucky, you shouldn’t have too much to worry about. It won’t automatically guarantee a bumper crop, of course, but it certainly helps!