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You are here: Home arrow Articles arrow Grow your own arrow Growing Tomatoes


Growing Tomatoes

Written by Behemoth

Tomatoes are short lived, tender perennials of the same family (solanaceae) as aubergines, capsicums and potatos. However we actually grow them as tender annuals. There are two main types of tomato that go by several descriptions:




Vine tomatoes require support for a central stem with its side shoots removed. This can reach several metres long in ideal conditions if the growing tip is not removed. The flowers and trusses grow from the main stem. Vines are best managed in a greenhouse if grown in containers or grow bags.


Bush tomatoes are better for growing outside and don’t require the support that vine tomatoes need. Bush tomatoes are more compact and don't need the support that vine varieties require. Grown outdoors they will crop earlier and more abundantly than vine tomatoes in the same situation. You could also grow them on greenhouse staging to get a very early crop.

There are also indeterminate types that are half-way between bush and vine. They usually require some loose support but side shoots are not nipped out.

Growing Indoors

The key is heat and light. You can provide heat in January but there wont be enough light, unless you provide that as well. So wait until February if you can provide heat and even later if you can’t.

If you can provide heat, tomatoes need a minimum temperature of 18 °C to germinate. This can be dropped to 12 °C at night once the seedlings are established. These plants should be ready to plant out in about eight weeks (mid April) and should be producing fruit from June or July.

To prevent leggy, stretched seedlings, sow thinly and prick out as soon as they are large enough to handle. Alternatively sow two seeds per 2 – 3 inch pot and remove the weaker seedling later.

Plant out in the greenhouse when the first flower on the first truss has opened. If you plant too early the first truss may abort. The plants should be no more than 9” tall at this time. Plant them in the greenhouse border, grow bags or pots. Large pots are a better proposition than grow bags, or double one grow bag on top of another to give good root depth and make watering more effective.

Put the supports in now before the plant grows and gets in the way and actually needs the support. Canes to the roof are good support, or run a wire across the roof of the greenhouse and hang strong Nylon twine down to the plant, the plant can then wind itself around the twine.

Water regularly and evenly to avoid black patches on the end of the fruit (blossom-end rot) and to stop the fruit splitting. Feed regularly but don’t overdo it.

As trusses ripen, strip leaves off the plant around the base, below the first trust from the ground. Green leaves are helping to support the plant and fruit production, they also provide some shade, preventing scorching and hard green areas around the stalk (greenback).

Watch the temperature and ventilation. Temperature is critical for fruit pollination and development of tomatoes. The fruit will not set if the temperature falls below 12 °C or goes over 33 °C.

Vine or cordon varieties need the side shoot nipping out while they are still small. This minimises damage to the stem and prevents energy being put into unwanted growth. You can recognise side shoots as they grow out of the main stem at about 45 degrees, usually at a joint between a truss and the main stem. Plants will often produce a side shoot at the growing tip so remove these as well. Unless you’ve masses of space, it’s usually advisable to nip out the growing tip when the plant reaches the eaves. The plant then concentrates its energy into fruit production.

Greenhouse varieties: Shirley F1; Sun Belle (cherry); Vanessa; Santa F1; Diplom F1; Sweet Million (cherry), Essex Wonder.

Growing Outdoors

If you don’t have a greenhouse, you’ll have to wait a bit and not try to grow a variety that specifically says it’s for greenhouse cultivation or ‘prefers sheltered conditions’.

Sow indoors no more than eight weeks before the last frost is expected. You could sow earlier and take your chances putting the young plants in a cold frame or cloche, but they may be too large to plant out before the risk of frost has passed.

Sow in warm conditions as above and grow on in warm well-lit conditions. A windowsill is good for light, but watch the temperature. Feed after about 3 weeks. Harden off when risk of frost has passed and plant out when the roots have filled the pot and the first flower buds appear.

You’ll need to put in suitable supports for vine or cordon varieties. Make sure that your support is sturdy as there’ll be quite a bit of weight on it at the end. No more than four or five trusses can be relied on to ripen outdoors before autumn frosts strike – even if you manage to avoid blight - so when enough trusses have set fruit, pinch out the growing tip, leaving two leaves above the top truss.

Bush types won’t be offended if you give them a bit of fleece for protection and maybe some modest support if they are trailing on the ground.

Water and feed regularly but remember overwatering and overfeeding can reduce flavour, so treat them a little bit mean. If leaves become pale or are shed try a potassium-rich fertilizer.

As above, remove lower leaves and side shoots in cordon varieties.

Alfresco, Tornado and Tumbler are some varieties to consider growing.

Potting up, planting out

Tomatoes will root from the stem if it is buried, this can be useful in ensuring a healthy root system, especially in plants that are leggy, they can be buried as deep as required, just remove any leaves that will end up below soil level.

Saving Tomato Seeds

When you get into tomato growing you will soon discover a vast wealth of varieties to stock your garden with. Some of them are common, cheap, even free on the front of magazines, so really there isn't any desperate need to save them for next year. But some varieties are now extremely rare or at least uncommon, and you can save yourself a packet (and help preserve rare breeds of tomato in the process) by saving seed from this years tomato crop to grow next year.

As luck would have it tomatoes are amongst the easiest to save. Most varieties are not only self fertile but also inbreeders; the exception being some of the potato leaved varieties and the ones with fancy double flowers so in principle you can save seed from a single plant. You'll be better off (more chance of getting good seed) if you can grow them in a small block of six, eight or more, but I've successfully saved seed from a single plant on many occasions.

The easy way if you only want to save a few seeds for your own use is to pick good ripe fruit from representative, healthy plants. If one of the plants is a runt or has odd fruit, for example, leave that one be (unless you're desperate to develop your own strange tomato breed!). Mash up the seedy pith from the tomato in a sieve, giving it a good wash under the tap and rubbing off as much of the mush as possible. Leave the seeds on a square of kitchen roll or a bit of paper towel and allow them to dry out somewhere warm ish but out of direct sunlight. When they're dry, pop it in an envelope or a jamjar and keep it somewhere cool and dry till next year. The seeds will most likely stick to the paper, and you can either cut them out or rub them off to plant. One trick I saw my dad do was to plant the tissue, and then pick out the healthiest seedlings to grow on.

GYO Forum

Growing tomatoes has been developed into a fine art, so if you have any comments, tips or suggestions on techniques and varieties, why not click here to go to the GYO forum. Why not have a look at the other topics while you’re there?