This British Tomato Fortnight, our technical manager Vicki Wright shares her tips for top-notch tomatoes…
Home-grown tomatoes are a delicious and rewarding crop to grow for the summer. And whether you grow them undercover, in pots, or in the ground – there’s a few key things to remember to ensure your salads, sandwiches and sauces are well supplied.
1. Training and taming your tomatoes
Tomatoes are divided into two growth types: cordon (indeterminate) and bush (determinate). Tall growing cordon tomatoes require their side shoots removing as the stem grows. This is the new, lush growth between the axis of the main stem and the leaf joint. Snip with sharp scissors or between finger and thumb.
Pinching out provides good air circulation around the fruits and allows sunlight to reach them. It also focuses the plants energy into fruit production. Sprawling bush varieties are low maintenance, but you should remove some leaves to allow sunlight to ripen the fruits.
2. Successful indoor tomatoes
As your plants grow, remember to monitor for pests such as whitefly. Remove infected parts or grow companion plants such as marigolds to attract the flies to these rather than your prized tomatoes. A problem I’ve had on my glasshouse tomatoes is greenback – a green or yellow discolouration on the shoulders of the fruit. This is triggered by high temperatures and causes the top of the fruit to harden and not ripen.
Tomatoes grow best at a constant but not excessive temperature, approximately 20C. To achieve this, you can add shading to your greenhouse or damp-down the greenhouse floor. There are also greenback resistant varieties available such as Alicante.
3. How to grow tomatoes outdoors
If you’re growing outdoors, choose a variety that’s suitable for your climate and is blight resistant such as Crimson Crush. You will need to harden the plants off before leaving them overnight. This is not just to get them used to the temperature changes, but for wind stress and light levels too. Site your plants in a sheltered sunny spot for a few days to keep an eye on them before you plant them out.
Be aware of the signs of tomato blight, particularly when growing outdoors in a rainy summer. Watch out for brown patches beginning on the leaf edges and spreading up the leaf towards the stem. If any of your plants are infected, discard them immediately and do not put them in your home compost.
4. Best ways to water your tomato plants
Ensure tomato plants are watered regularly and the compost is evenly watered. The change between wet and dry compost can cause issues. Try to water at the same time each day, preferably at the beginning of the day. Keeping the compost consistently moist supports fruit development and avoids blossom end rot and splitting. Irregular watering reduces the flow of nutrients up the plant and into the fruit causing a brown spot to appear on the bottom of the tomato. If this happens to your tomatoes, adjust the watering, and remove the damaged fruit. If you are going away, consider an automatic watering system with a timer but test it before you leave it.
5. Tomato feeding tips
When the first truss of flowers appears on the stem, begin feeding with a high potassium liquid feed. This can be a general tomato feed, seaweed feed for tomatoes or comfrey and should be done weekly.