The Basics of Growing Tomatoes

Tomatoes are among the most popular crops cultivated across the globe. Maximising their potential requires that farmers understand the basics of growing them successfully and profitably.

Moreover, as the seasons transition from winter to spring, this presents conducive weather conditions for growing tomatoes.

The starting point is for a farmer to understand that tomatoes have varying types (cultivars) that can be produced. There are fresh market varieties that a farmer can grow for household and food establishments. Furthermore, there are cultivars best suited for processing or canning purposes, and those used in certain dishes or beverages, such as cherry tomatoes.

To this end, it is important to consider the type of tomato demanded by your target market before you venture into production.

Another essential point to note is the ideal sowing time for tomato seeds, which is conventionally around mid-August. Transplanting can be done in early September. At the sowing stage, it is vital to sow tomato seeds in seed trays, at a depth of 1cm.

Once the seedlings start growing in the seed trays, it is essential to prepare the soil in the garden where the tomatoes will be grown until they reach maturity.

The soil must be cultivated to a depth of 20 to 30cm and should incorporate NPK (fertiliser) 2:3:4 (38) + 0,5% Zinc at a ratio of about 100 grams per m2.

Moreover, the soil must be prepared and irrigated daily. After three weeks, the seedlings in the trays can be transplanted into the garden. This must be done in the evening to avoid heat stress.

At transplanting, it is essential to follow spacing recommendations of 40cm between rows and 30cm within rows when growing indeterminate varieties. On the other hand, determinate tomatoes can be grown at spacing recommendations of 70 to 140cm between rows and 40cm within rows.

Once transplanting is done, it is essential to follow a water requirement of about 500mm throughout a 90 to 120 day growing cycle. Therefore, each plant needs about 5,56mm per day if grown over a 90-day period, and about 4,17mm per day over a 120-day period.

Essentially, farmers must develop a fixed irrigation programme as uneven irrigation may cause fruit cankering (cracking). During the growing period, it is important to understand the beneficial effect of fertiliser application for the successful growth of tomatoes.

To this end, during the first three weeks after transplanting, applying nitrogen and phosphorus based fertilisers to stimulate foliage (leafy) growth and a successful establishment of a robust root system, is essential. This can be maintained until the tomatoes start flowering, then potassium based fertilisers such as KSO4 (potassium sulphate) to ensure fruit quality, must be applied.

Furthermore, it is vital to ensure the plants are pruned to ensure that only the vines with flowers are left. This concentrates the supply of potassium to fruit development. At flowering, it is essential to offer support to the tomato plants by staking. This is done by securing the plant with a stick to ensure it stays upright when bearing fruit.

Essentially one must keep pests (red spider mites, cutworms, whiteflies and tomato rust mites) and fungal diseases (early and late blight) at bay by implementing a spraying and dusting plan. Moreover, farmers are encouraged to scout for pests and diseases daily to swiftly respond to outbreaks.

Furthermore, after growing tomatoes, it is advisable to plant a different crop to minimise overutilisation of nutrients.

Lastly, always remember that when the basics are done correctly from the start, it enables the plants to grow optimally and offers a farmer good yields, sales and a sustainable income.

• Hanks Saisai is Agribank’s technical adviser for crops and poultry.