Growing tomatoes can be an obsession.
Delightful to eat, really full of flavour, and having a genuinely different, more intense tomato taste, than those bought in shops – all these reasons make growing tomatoes my favourite allotment vegetable.
- February to May
- Planting depth: Surface sow, fine covering
- Planting spacing: 60 cm between plants, 100 cm between rows
- June – October
- Eat fresh. Surplus tomatoes can be turned into chutney, or sauces and then frozen.
Tomatoes can be divided into the following two main types:
- Bush tomatoes (determinate)
As the name suggests, these grow as a bush and do not need special pruning or support. Bush tomatoes include many cherry tomatoes and tumbling varieties, suitable for growing in pots or hanging baskets.
- Cordon tomatoes (indeterminate)
These varieties generally produce standard size tomatoes as well as the larger beefsteak varieties. The cordon varieties need both supporting and careful pruning. The pruning regime is especially important to encourage the plant to invest its energy on a controlled number of ripe fruit, otherwise the short summers typical of the UK climate can leave a gardener staring at a large leaf covered plant covered in small green tomatoes – that never have time to ripen.
The most common problem in growing tomatoes is blight. If you have the space, investing in a plastic growhouse, greenhouse, or polytunnel will transform your success rate. If not, resort to disease resistance F1 varieties. I hope this guide on how to grow tomatoes will help too.
I like to start the germination process early, in February or March, on a warm windowsill. By starting early, I have ripe tomatoes by the end of June, and the harvest will be spread out over more weeks.
I use small plastic pots nearly full with multi-purpose compost. I water the pots to make sure that the soil is wet, and only after this do I sprinkle a few seeds on top of the soil (about 3 or 4). I deliberately wet the soil before sowing the seed, as this avoids them either being dragged too deep by the water into the soil, or washed off the top of the pot.
The final two steps are to cover the seeds with a thin layer of perlite, and wrap the pots with cling film. This avoids the need to water again until after the seeds have germinated. As soon as I see the first seedlings, I remove the cling film.
I prefer not to buy tomato seedlings from garden centres as it ends up being expensive (compared to seeds) and I find they fruit later in the summer.
I prefer to wait until the plants grow at least two tomato like leaves before potting on. This is a sign that each seedling has developed a good root structure, although it is sometimes a little tricky to pull apart the roots of seedlings sharing a pot (using a pencil helps).
A key decision is how long to leave tomato seedlings growing indoors, versus the more healthy full sun option out of doors, with the potential lethal risk of frost. It is one of the reasons why I recommend growing tomatoes in pots in a tomato greenhouse – it just makes the process a lot easier.
When the weather is ready, a good tick is to plant each tomato seedling deep inside a big pot, even covering up some branches with soil. Tomatoes are like geraniums in that they throw out new roots with ease. The process of planting deep will lead to a much stronger plant able to produce more tomatoes. I like to use a big pot, at least 30 cm wide and deep. The better the compost the healthier the plant. Homemade compost is ideal.
For the commonly grown indeterminate types of tomatoes, it is important to prune regularly. Left unpruned, a tomato plant will turn into a very thick bush, and then collapse in a heap. Removing unnecessary branches both concentrates growth into the fruit, and perhaps just as importantly, allows light and air to circulate around the plant. This helps stop plants getting the dreaded blight.
Remove diagonal side shoots as soon as they appear. These are the ones that appear in the elbow between the trunk and a lateral (horizontal) branch. However, do not remove other branches that are not in an elbow between a trunk and a branch. These branches are likely to be the fruiting spurs (trusses) you are waiting for! You may like to see this page on how to prune tomatoes.
Once flowers appear, these will soon be replaced by tiny green balls, ready to bulge into glorious ripe tomatoes. The ripening process can take some time, especially in wet summers. The best ripening weather would be a hot and sunny July and August, complemented by lots of watering.
For indeterminate tomatoes, it is frequently recommended to limit the number of flowering trusses to around six. Once these have developed, any further trusses that form are pruned away to concentrate energy into the developing fruit. Similarly, the growing tip at the top of the plant should be removed, and careful attention given to removing any unnecessary side shoots, and new stems growing from the base of the plant.
For determinate varieties (bush varieties like cherry and tumbling tomatoes) there is no need to limit the number of trusses.
Tomato compost should always be kept moist. Tomato plants tell you when they are unhappy, they sulk like a teenager, with droopy shoulders and turned down leaves. The joy is that with a little water, they soon return to standing tall and bushy.
A tomato plant laden with tomatoes has to support a considerable amount of weight. Outdoor tomatoes will need tying to a stake. Greenhouse or polytunnel tomato plants can be grown up twine suspended from the roof frame. Wrap the twine around the length of the plant to support the trunk, as well as using additional twine to support the branches.
See tomato varieties.