The tomatoes in your garden will thrive if you pay attention to pruning and trellising the plants. Healthy plants, higher yield.

Sometimes the tomato plants in our gardens get so large and so unwieldy that we begin to wonder if we should prune them. Some people firmly believe that pruning tomato suckers improves the production and health of a plant. Others claim that pruning tomato suckers damages the plant unnecessarily, opens the plant to disease and does nothing to help the plant. So the choice is yours.

However, you should only prune indeterminate varieties, which produce new leaves and flowers continuously through the growing season. Indeterminate plants need extra-tall supports of at least 1.5 metres. Because indeterminate varieties throw out so many shoots, gardeners often prune them for optimum-sized fruit or train them on a very tall trellis.

Determinate varieties (including bush varieties) reach a certain plant height and then stop growing. The majority of their fruit matures within a month or two and appears at the ends of the branches.

Advantages of pruning

Maximizing photosynthesis: Leaves need to receive light in order to make sugars for growth and fruit set.

Improving airflow and decreasing disease: With fewer leaves, pruned plants are less dense, allowing more air to move through the plants. The leaves dry faster after a rain, so they are less susceptible to the diseases that need prolonged moisture to develop.

Bigger fruit: Pruning at the right time directs energy toward creating and ripening fruit instead of making more leaves.

Earlier ripening: When a plant’s leaves and physiology have fewer fruit to take care of, that fruit ripens faster.

Better tasting tomatoes: All those plant sugars being channelled into the fruit often means better flavour as well.

How to prune

pruning trellising tomatoes
Topping your tomato plant.

It’s best to prune when the plants are about half a metre tall. By the time your tomato plant gets to be this size, the plant will have branches coming off the main stem.

Where these branches meet, you will see and additional branch growing. This is called a tomato sucker. Try to remove suckers when they’re small enough to pinch with your fingers, so you don’t leave a gaping wound on the stem. If you prefer, you can use a sharp, clean pair of pruning shears to snip these small sucker branches off.

The best time to prune tomato plants is in the early morning on a dry day. This will allow for the wounds from the pruning to heal cleanly and will reduce the chances of the plant being infected by disease. If you choose to prune tomato plants, make sure that you use watering methods that water the tomato plants at the soil level (like soaker hoses) rather than from above (like sprinklers). This will prevent the splashing of soil up onto the tomato plant and the tomato plants wounds.

Topping

As the growing season draws to a close, tomato plants are often still loaded with fruit. To speed ripening late in the season, remove the growing tip of each main stem about four weeks before the first expected frost. Called “topping,” this type of pruning causes the plant to stop flowering and setting new fruit, and instead directs all sugars to the remaining fruit. This way, the fruit will ripen faster, plus it becomes more likely that the green tomatoes that you pick before the frost will actually ripen when you bring them indoors.

Trellising Tomato Plants

Some permaculturists are in favour of allowing the plant to grow without staking or training. They maintain that the plants become stronger, and as the plant spreads, it sends down new roots so it is hardier and produces more fruit than normal. They recommend mulch to protect tomatoes that touch the ground.

But most vegetable experts prefer to provide tomato plants with some support, particularly indeterminate varieties, which grow like a vine. Determinate varieties will grow large like a bush with their height being just over a metre.

The reasons put forward for “training” tomato plants include maximising space, making harvesting easier, improving air circulation which helps to prevent diseases and creating visual interest. Strategically placed trellises can also provide privacy screening and afternoon shade.

How to trellis

The most obvious is to stake each plant by driving a wooden or metal post into the ground and tying the plant to it.

pruning trellising tomatoes
Teepee trellising.

If you have a plentiful supply of bamboo poles you can construct tepees, using three or four poles tied together to form a cone around the plant. Another version of the tepee is to tie two poles together to form an A, then sink another pair about a metre away, followed by a third. Then place the last bamboo pole across the top of the structure in the “V” created where the poles meet, connecting all the tepees together. Tie twine from one pole to the next along each side. Leaving about 50cms between each line, continue up the tepee structure. You should have about 3 or 4 lines strung up by the end. This reinforces the structure and adds support for the tomato plants as they grow and climb.

pruning trellising tomatoes
Florida weave trellis.

Another option is the basket weave, where the idea is to “sandwich” your plants between lengths of twine. The twine gently holds up the plants without the need for additional stakes and clips. If you are planting your tomatoes in a line, plant them about 60 cm apart. Wait till they are about 30 cm high. Place a stake between every two or three plants, and pound at least 30 cm into the ground, depending on how much wind your garden gets in the summer. Tie baling string to the end stake, wind it around the plants to the next stake and then back again to the first stake, creating a figure of eight pattern. As your tomato plants grow taller, weave additional lines of twine about every 20cms up the stakes. Carefully tuck in any stray branches.

This method is also known as the “Florida weave”.

Then there is the T-post trellis, where you string your tomato plants vertically, from a top bar attached to two stakes. Using found items such as downed tree limbs, this method is a good one for smallholders who don’t want to spend a lot of money on materials.

Rotate your crops

If you are going to leave your trellises in place, you should rotate the crops that you plant there each season. This is done to prevent crop-specific pests and diseases from building up and carrying over from one season to the next in the soil. If you move the crop, the problem has no host on which to live. Ideally, rotate a vegetable or vegetable family so it grows in a particular spot only one year out of three. Vegetables that are members of the same botanical family are susceptible to the same problems, so try to follow members of one family with members of a different family.  The tomato is in the same family as brinjals, peppers and potatoes. So next season rather plant cucumbers, beans or peas against the trellis.

Also think about the crops that you plant near the tomatoes. Practicing companion planting can increase yields. Some plants also help deter pests and attract beneficial insects. Some vegetables or herbs that  that you might consider planting in the shadow of your tomatoes include asparagus, basil, borage, carrots, cucumber, onions and chives, spinach, lettuce, nasturtiums and marigolds.

This is part two of a series on growing vegetables from the Nightshade Family. Next we will look at tomato pests and diseases. To ensure you don’t miss out on the rest of the series, subscribe here to receive our Feature Newsletter at the end of the series.

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