The prospect of tackling tomatoes often scares novice gardeners but there’s no need to be frightened. It’s true that getting your head around what goes on inside a greenhouse is probably best left to those who have already been gardening for a while. But growing tomatoes outdoors is pretty straightforward, especially if you follow my simple, step-by-step guide. Anyway, many gardeners believe that tomatoes grown outdoors have a better flavour than those raised in greenhouses. There’s only one way to find out if you’re up to the challenge and that’s to take the plunge and grow your own!
Lesson 1: Sowing the Seeds
1.1) Plant Types
Outdoor tomatoes fall into two categories, cordon and bush. Cordon varieties produce fruit on laterally growing branches (cordons). They grow to around 2m in height and have to be supported. Bush tomato plants are much shorter – around 60cm – and don’t need supporting. Getting to the fruit can sometimes be tricky. Unless you place straw beneath the plant, the tomatoes often end up in the dirt.
1.2) Starting Off
Cordon plants will produce fruit all summer, in contrast to bush varieties, which tend to crop over a shorter period. This characteristic sometimes leaves you with more ripe tomatoes than you can eat, so we’re recommending cordon plants for our project. Start your tomato plants by sowing two seeds each in 7.5cm pots filled with moist – but not waterlogged – potting compost. Cover lightly with the potting compost and place on a windowsill. In a few weeks’ time, you’ll be transferring the small plants into growing bags. There’s more on this topic in a later lesson.
1.3) Try These
“Gardener’s Delight” has earned its reputation as one of our most popular outdoor tomatoes. This cordon plant produces a heavy crop of small, tangy fruit. “Sweet 100” is another popular cordon variety. If you’re attracted to bush varieties, try “Red Alert”. It’s a relative newcomer to the scene but has swiftly become a favourite.
Lesson 2: Growing Tomato Seedlings
2.1) Into the Light
Tomato seedlings normally emerge between one and two weeks after sowing. A light location such as a windowsill is a good place to grow your seedlings but don’t position them in direct sunlight all day. Too much sun may burn the young leaves. Once the seedlings are big enough to handle, remove the weaker plant. Don’t forget to water the seedlings. If the surface compost is dry, you’ve definitely left it too long.
2.2) All Change
After around four weeks, the roots of the seedlings should start to peep out of the bottom of their 7.5cm pots. They need more growing room but they’re not ready to go into growing bags yet. Transfer them into 12.5cm pots to finish off the first stage of the growing process. They should be ready for transplanting into growing bags in another three weeks.
2.3) Choosing Growing Bags
In the next lesson, we’ll be looking at transferring your tomato plants into growing bags. Although that stage is still a little way off, it makes sense to buy the growing bags now. They’re popular items and garden centres can run out of them. The last thing you want is several tomato plants bursting out of their pots and no growing bags to transplant them into! When choosing growing bags, go for quality. They may cost a bit more but they’ll give you much better tasting tomatoes. Cordon varieties need supporting. If you plan to position your growing bags on the earth, you can use garden canes to support the plants. But, if the bags are destined for a patio or other hard surface, consider using a support frame specifically designed for growing bags.
Lesson 3: Transferring Tomatoes to Growing Bags
3.1) Making the Switch
Your young tomato plants are ready to be transferred into growing bags when they are around 15cms tall, or by the time that flowers have just started to form on the first “truss” (branch). Before making the transfer, you need to prepare the growing bag. Knead it thoroughly to loosen up the compost, which may have settled during storage. Good quality growing bags usually have three circles cut in them for plants. Make a few holes in the underside for drainage and then cut out the planting holes.
3.2) Stake Out
Heap up the compost slightly, removing some to make room for a tomato plant. Position the plant in a depression so that the surface of the root ball is slightly below that of the compost. Cover the root ball with a thin layer of compost, firm in the plant and water. If you’re planting a cordon variety, use a growing bag frame to position a vertical cane next to each plant. Bush varieties won’t need extensive support but a single cane may nevertheless be helpful. As the tomato plants develop, tie them to their canes with loose loops of soft garden twine. Review these fixings periodically: tight or awkwardly placed loops may restrict growth.
3.3) Tomato TLC
There’s no doubt that growing bags provide a convenient environment in which to grow vegetables. But most gardeners agree that looking after crops grown in this way takes more work than tending vegetables raised in the ground. Regular watering is a must. Tomatoes shouldn’t be waterlogged but they do need plenty of water. Experienced gardeners sometimes reduce the amount of water they give their tomatoes in order to improve the flavour but in these early stages you should concentrate on keeping the compost moist by watering little and often.
Lesson 4: Caring for Young Tomato Plants
4.1) Training Programme
Tomatoes are ready for picking 16-20 weeks after sowing, depending on the variety grown and the environmental conditions. So you’ve got a while to go yet before you can enjoy your home-grown toms. Meanwhile, water the plants little and often and feed them with a potash-rich liquid tomato fertiliser every week. The other main focus at this stage in their development is to train the plants so that they produce the maximum amount of fruit. If you’re growing a cordon variety, the way to do this is by limiting the number of “trusses” (flowering branches) that the plant is allowed to develop.
4.2) Pinching Out
Cordon varieties have a central stem that produces leaves and trusses. Once a truss has been established, monitor the plant for side-shoots emerging from joins between the leaves and the stem in that area. Pinch them out so that the plant concentrates on growing your chosen truss. As the plant grows, remember to tie it loosely to its supporting cane. Bush varieties don’t need this intensive training. They should be sturdy enough to cope without support and there’s no need to limit the amount of shoots that they develop.
4.3) Troubled Tomatoes
As the plants develop, lower leaves may begin to discolour or decay. Remove them promptly to avoid the spread of disease. Two of the most common tomato problems are fruit that split and blossom end rot. Split fruit are easy to recognise. Blossom end rot is distinguished by a dark, leathery patch on the bottom end of the fruit. Handily, they both have the same cause – an uneven watering regime. Don’t allow the compost to dry out and then flood it with water. We’ve said it once already in this lesson but it’s worth repeating: growing bags must be watered little and often if the weather is dry.
Lesson 5: Training Tomato Plants
5.1) Exciting Times
The formation of trusses (flowering branches) signals the start of an exciting phase for tomato-growers. Once the flowers die away, it won’t be long before the fruit will begin to develop. If you’re growing a dwarf variety, you can sit back and enjoy watching perfect little tomatoes form. But growers of cordon varieties need to keep their wits about them. This is not a time to get complacent!
5.2) Positive Energy
The first priority for cordon-growers is to continue the policy started in Lesson 4 of making sure all the plant’s energy goes into producing fruit. Pinch out side-shoots before they have a chance to take hold. This will mean inspecting your plants regularly because growth can be vigorous during this period. Outdoor tomatoes naturally tend to produce only four useful trusses. So there’s no point in allowing the plant to waste its energy once small fruit have begun to develop on the fourth truss. When this occurs, pinch out the growing tip of the main plant two leaves above the fourth truss.
5.3) A Regular Life
Whether you’re growing dwarf or cordon varieties, you’ll need to make sure that the plants are watered and fed regularly. Growing bags don’t hold much water, so little and often is the rule. Yes, we know we’ve said this before in previous lessons but we want you to have lovely, healthy tomatoes! Read the instructions for applying liquid tomato fertiliser carefully but use your common sense, too. For example, tomato feed diluted in 4.5 litres of water may swamp a growing bag if given at one application, especially with younger plants. It may be better to spread early feeds out over two applications. When feeding and watering, it’s a good idea to remove the rose from your watering can. That way, you can direct the nozzle at the roots. Finally, now that the plants are growing thicker and stronger, don’t forget to check that the ties you put in place some weeks earlier aren’t cutting into the stems.