Tomato Staking and Trellising: Keeping Open-Field Tomatoes Up and Healthy in the Short Rains

Walk past an unstaked tomato field three weeks into the short rains and you can usually smell the problem before you see it. The vines have flopped over, the lower trusses are lying on wet soil, half the fruit has a soft brown patch where it touched the ground, and the leaves are so tangled that the sprayer only wets the top layer. Late blight moves through a crop like that in days. The farmer did everything right with seed, fertiliser and spraying, and still loses a large share of the harvest to a problem that a few poles and a roll of twine would have prevented.

Staking and trellising is the least glamorous job on a tomato farm, and one of the most profitable. It lifts fruit off the soil, lets air move through the canopy so leaves dry faster after rain, lets your spray reach the underside of the leaves, and makes picking quicker and cleaner. In an October planting, when rain, warm nights and wet leaves favour disease, it matters more than at any other time of year.

This guide covers open-field tomatoes on a Kenyan smallholding: which varieties need support and which can manage with less, the three main support systems and when each makes sense, how to build the popular stake-and-string system step by step, how to prune and tie as the crop grows, and the tools that make the work faster. Spacing and pruning figures below are general practice; your seed supplier and county agronomist can give the figures for your variety and site.

Know Your Variety First: Determinate or Indeterminate

Tomato varieties fall into two growth habits, and the habit decides how much support the crop needs. Determinate varieties grow to a fixed height, set most of their fruit over a few weeks, and then stop. Many of the open-pollinated processing types long grown in Kenya, such as Rio Grande and Cal J, are usually described as determinate or close to it. They stay fairly compact, but a heavy fruit load still pulls them over, especially in wet soil.

Indeterminate varieties keep growing and flowering for as long as the plant stays healthy, adding a new fruit truss every few leaves. Many of the hybrid varieties sold in Kenya for fresh market, including several popular F1 types, are indeterminate. Left on the ground, an indeterminate plant becomes a sprawling mat. Trained up a support on one or two stems, it keeps producing over a long picking season and gives cleaner, larger fruit.

The seed packet or the stockist will tell you which habit you are buying. If it says indeterminate, plan a tall support from day one. If it says determinate, a shorter, lighter system is usually enough, but going without any support in the short rains is a gamble most farmers lose.

The Three Common Support Systems

There are many ways to hold a tomato up, but three cover almost every open-field farm in Kenya.

1. Single stakes. One pole per plant, with the stem tied to it at intervals as it grows. It is simple, easy to understand and suits a small kitchen garden of a few dozen plants. On a larger plot it uses the most poles and the most tying time, and the poles are the expensive part.

2. Stake and string (the "Florida weave"). A strong pole at each end of the row and a pole every two or three plants between them, with twine run along both sides of the row and woven between the plants at intervals as they grow. The plants are sandwiched between strings rather than tied individually. It needs far fewer poles than single staking, tying goes quickly, and it suits determinate and semi-determinate varieties well. It is the system many commercial open-field growers use.

3. Overhead wire with hanging strings. Tall poles at each end of the row and at intervals along it carry a wire stretched about 1.8 to 2 metres above the ground. A string hangs from the wire down to the base of each plant, and the stem is wound around the string as it grows. This is the standard method in greenhouses, as our greenhouse equipment guide describes, and it works outdoors for indeterminate varieties pruned to one or two stems. The end posts take a lot of strain, so they must be thick, deep and braced.

Building a Stake and String Row, Step by Step

Because stake and string is the system most farmers can afford on a quarter acre or more, here is how to build it properly.

Choose the poles. For determinate varieties, poles that stand around 1.2 to 1.5 metres above ground are usually enough. For indeterminate varieties you need taller support, nearer 1.8 to 2 metres above ground. Add the depth you will drive into the ground: a pole that is not firmly anchored will lean once the row carries a full fruit load and the soil is soft. End posts should be noticeably thicker than line stakes. Treated or naturally durable timber lasts longer, and a pole that has rotted at ground level will break exactly when the crop is heaviest.

Sharpen and drive. Point each pole with a panga or axe so it goes in straight, and drive it with a mallet or the back of a heavy hammer. In hard ground, make a pilot hole first with a crowbar. Brace the end posts with a diagonal pole or an anchor, because they carry the tension of every string in the row. If the head of your hammer or axe is loose, fix it before you start; our guide to rehandling hammer and axe heads shows how.

Space the stakes. Put a line stake every two or three plants. Closer spacing holds more weight and lets the strings sag less, which matters with heavy-fruiting varieties.

Run the first string. When the plants are roughly 20 to 25 centimetres tall, tie twine firmly to the end post at about that height, walk down one side of the row and loop it once around each line stake, keeping it tight, then tie off on the far end post. Come back down the other side of the row the same way. The plants are now held between two strings.

Keep adding strings. Every time the plants have grown another 20 to 25 centimetres, add a new pair of strings above the last. Do not wait until plants are leaning badly; a string run over an upright plant takes a few minutes, while lifting a flopped plant back into the row damages it.

Use a twine that will not stretch much when wet and that will last the season in sun and rain. Polypropylene twine is common; natural sisal is cheaper and compostable but can weaken faster in wet weather. Whatever you use, buy enough for several strings along the full length of every row, plus spare.

Pruning and Tying as the Crop Grows

Support and pruning work together. A support only helps if the plant is kept to a shape the support can hold.

Suckers. The side shoots that grow in the angle between a leaf and the main stem are called suckers. On indeterminate varieties trained to a single stem or two stems, remove suckers regularly while they are small, by snapping them sideways with your fingers. A single-stem plant gives earlier, larger fruit; a two-stem plant (the main stem plus the first strong sucker below the first flower truss) gives more fruit per plant from the same number of seedlings. On determinate varieties, heavy sucker removal reduces yield, because the side shoots carry much of the crop, so prune them lightly or not at all and follow the seed supplier's advice.

Lower leaves. Once the first truss is picked, or as the lower leaves yellow, remove the leaves below the lowest fruit truss. This keeps foliage off the soil, where rain splash carries disease spores, and opens the base of the plant to air.

Ties on single stakes and strings. Where you tie a stem to a stake, use a loose figure-of-eight loop: the twine crosses between stem and stake so the stem cannot rub against the pole, and there is space for the stem to thicken. A tie pulled tight around a young stem will cut into it within weeks. On the overhead string system, wind the stem gently around the hanging string in the same direction each time, a little every few days.

Why Support Pays Off in the Short Rains

The benefits of staking are well established in vegetable extension advice in Kenya and elsewhere, and they all come back to the same mechanisms.

Fruit off the soil. Tomatoes lying on wet soil pick up soil-borne rots and are more likely to be damaged by pests at ground level. Fruit hanging in the air stays cleaner, and clean fruit grades better at the market.

Leaves dry faster. Late blight and many other leaf diseases need the leaf surface to stay wet for hours. An upright, opened canopy with space between plants lets wind and sun dry the leaves sooner after each shower.

Better spray coverage. Fungicides and insecticides only work where they land. In a tangled, flopped crop, most of the spray hits the top surface of the top leaves. In a trained row, a properly calibrated knapsack sprayer can reach both sides of the row and the undersides of the leaves. In wet weather, timing matters too, and our guide to spraying in the rainy season explains rainfastness. For any chemical, follow the label and ask your agronomist for the right product and rate.

Faster, cleaner picking. Pickers can walk the rows and see the fruit, so fewer ripe tomatoes are missed and fewer are trampled.

Costs, Reuse and Hygiene

Poles are usually the biggest cost of any support system, which is why stake and string, with one pole every two or three plants, is so popular. Well-chosen poles last several seasons if you pull them at the end of the crop, knock off soil, let them dry and store them under cover, off the ground.

Reusing poles and strings has one risk: disease carried over from the last crop. Tomato diseases can survive on plant debris clinging to poles and string. Never reuse old twine that was tangled in a diseased crop; burn or dispose of it with the crop residue. Scrub poles clean before storing them, and ask your agronomist whether a disinfectant treatment is advisable if the last crop had a serious disease problem. Rotate tomatoes away from land that has just carried tomatoes, potatoes, capsicum or eggplant, which share many of the same diseases.

Labour is the other cost. Stringing a row as the plants grow takes far less time than tying every plant to its own stake, and pruning on a trained crop is quicker because you can see every stem. On a plot big enough to need hired help, build the support and pruning rounds into the weekly work plan so they are not skipped in a busy week.

Field Checklist

Tools for the Job, With Prices

Most of the work needs only a few hand tools: a jembe for ridging and planting, a panga or axe to point poles, a mallet or heavy hammer, a crowbar for hard ground, a knife for twine, and a knapsack sprayer. These items appear on the Fuga price list at the time of writing; check the site or call a branch for current prices and stock.

Tomatoes that start well in the nursery are easier to train; our guide to seedling trays and transplanting covers that stage. For a sprayer, jembe or a full set of tools for the season, talk to any Fuga branch in Eldoret, Nairobi or Nakuru, or WhatsApp 0716 961 018.

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