According to a study in 2019, tomato farming in Kenya accounts for 14% of total vegetable production. Many regions in Kenya have the soil and climate suitable for this bright red fruit.

Tomato farming is a lucrative business. Every household consumes tomatoes, and they are the main ingredient in ketchup, tomato paste and almost every salad. This article seeks to provide a step-by-step guide to tomato farming, particularly for Kenya, but you can still follow it for other regions.

Tomato Seed Preparation

If you have the patience, you can begin your journey to tomato farming by sowing seeds. Tomato seeds germinate best when indoors at temperatures higher than 16 degrees Celsius. The best medium for these seeds is a seed starter mix. Avoid using garden soil because it might harbour pests and diseases that might kill the tomato seeds before germination. The price of tomato seeds in Kenya varies between sh200 to sh350 per gram. The price difference depends on the tomato variety and the company selling the seed.

How to sow tomato seeds

  1. Spread the seed starter mix on a container
  2. Sprinkle some water to make the seed starter mix wet but not soggy
  3. Divide the seed starting mix into smaller nurseries
  4. Create a small hole into the nursery with your hand
  5. Place one or two tomato seeds
  6. Moisten the nursery
  7. Cover with transparent paper to maintain warmth

Seed Preparation Tips

  • Ensure that the seed starter mix is in close contact with the seeds.
  • Strive to give the seeds four to six hours of direct sunlight every day.
  • Having two seedlings insures you in case one fails to germinate. If both seeds germinate, toss the weaker one out.
Tomato seedlings
Tomato seedlings that are ready for transplant.

Sowing seeds is a delicate process that can result in losses if not done right. If you are not familiar with sowing, you can hire a professional propagator to sow for them. Proceed to transplant once you notice a few leaves on the shoot.

Soil Analysis

Soil analysis determines your soil’s pH and nutrient level. It gives you an idea on how your tomato seedlings will perform once you transplant. You should adjust the pH and nutrient level to increase the yield of your tomato plant. You can take your sample soil to commercial laboratories like SoilCares Ltd, Crop Nutrition Laboratory Services Ltd and Kenya Agricultural Livestock Research Organization (KALRO).

A more convenient option would be to test the soil with a soil test kit from companies like Hach Company, Aqualytic Laboratories Limited or DLA Scientific Kenya. A soil test kit is not as accurate as analyzing in commercial laboratories, but it provides you with the required results on pH, nitrogen, phosphorus and potassium levels.

Tomatoes can grow on a wide range of soils, as long as they are well-draining. The optimum soil pH for tomatoes is 6 to 6.5. You can apply lime to raise pH or gypsum to lower.

Week 1 of Transplanting

A transplanted tomato seedling.

Transplanting is relocating tomato seedlings from the nursery to the soil. There are two things you should do before transplanting;

1) Harden Off the Seedlings

Hardening off is not necessary, but it increases the seedlings chances of survival. Transplanting might stress the seedlings due to a change in environment. You can toughen them up by altering their environment for ten days.

How to Harden Up Seedlings

  1. Create a shade outside that filters direct sunlight.
  2. On day 1, take the seedlings, while still on their nurseries, outside for a couple of hours.
  3. On day 2, repeat the process but let them stay out a bit longer.
  4. Take the seedlings out for ten days while increasing exposure time to sunlight each day.

2) Prepare the Soil

It would be advisable to loosen the soil a week before transplanting. Loose soil has more aeration pockets, making it easy for roots to penetrate. Dig at least 8 inches deep, spread compost then mix with the loosened soil.

Tomato Transplanting Tips

  • Transplant in the evening or the morning when is sun’s intensity is weak
  • Moisten the soil before transplanting
  • Avoid removing all the soil attached at the seedling

Week 2 to Week 7 of Vegetative Growth

Vegetative growth in tomato plants takes 40 to 50 days after transplanting. The plant will have matured by approximately the 30th day, during which flowering will begin. By the 75th day, the tomatoes will be ready to harvest. You need to ensure that your tomatoes receive enough water, though not too much that it leaches nutrients.

Fertilizer Application

Tomato plants require fertilizers for growth and flowering. A good tip would be to conduct a soil analysis before fertilizing. Soil testing will guide you on how much nutrients to or not to, add to avoid excessive or insufficient application.

The common nutrients applied as fertilizers to tomatoes are

Nutrient For Tomatoes Role Sources Risk of Excessive Application
Nitrogen (N) Promotes growth

Promotes leafing and flowering

Inhibits the development of diseases like root rot and fusarium crown

NPK, CAN, Urea, Ammonium nitrate, Ammonium Sulphate, Urea Ammonium nitrate Might reduce fruit yield
Phosphorus  (P) Promotes flowering

Encourages fruit development

Enhances ripening

Improves fruit quality

Helps root development

NPK, Ammonium phosphates, Nitric phosphates Inhibits absorption of zinc and iron, which causes an imbalance
Potassium (K) Promotes fruit colouration during ripening

Encourages even fruit ripening

NPK, Potassium Chloride, Potassium Sulphate, Potassium Magnesium Sulphate, Potassium thiosulfate Inhibits absorption of nitrogen, magnesium and manganese

Causes leaf yellowing due to magnesium and nitrogen deficiency

Inhibits growth due to nitrogen deficiency

Calcium (C) Enhances fruit firmness

Reduces risk of blossom end rot

CAN, calcium carbonate, Calcium hydroxide (hydrated lime), calcium oxide (quick lime) Raises the soil pH to levels higher than the optimum range, which affects growth.

For more details on the role of nutrients, you can check at Yara.

Tomato Fertilizing Tips

  • Excessive application of one nutrient limits the utilization of others.
  • Use nitrogen from nitrate sources as opposed to ammonium sources. Ammonium competes for absorption with calcium hence increasing the risk of blossom end rot.
  • Fertilizing close to the roots or stem of the plant might burn the plant. The fertilizers should not be in direct contact with the plant.
  • For vertical tomato farming and tomato hydroponic farming, the fertilizers can be added as a solution in the feeding water.
  • Water well before fertilizing

How to Fertilize Tomatoes

  1. Water the tomato plant
  2. Dig a small hole (about 3 inches deep), 6 inches away from the plant
  3. Scoop the fertilizer into the hole and cover with soil

Tomato Trellising

Tomato plants, particularly from indeterminate tomato varieties, grow to more than six feet tall. They become leafy, bushy and start to lean as if demanding support. Trellising keeps the tomato plant upright, enabling it to receive maximum sunlight and air.

There are many ways to trellis tomatoes. The common one is tying vertically with a string on a pole. It is good practice to trellis the tomato plants when still young, for instance at 2 feet height. You might damage or break the stem if you trellis after maturation.

Tomato Pruning

Pruning involves removing older branches, suckers and any other unproductive parts on the tomato plant. Pruning is necessary for the blossoming branches to receive adequate water and nutrients without competing with others.  It improves air circulation and minimizes the spread of diseases.

Tomato pruning
The older unproductive branches have been pruned to improve aeration and exposure to sunlight.

Harvesting Tomatoes

Tomatoes should be prime for harvest by the 75th day, though it depends on the variety. Get ready to harvest once you see your tomatoes ripening.

Use the change in colour from green to light red as your indicator for harvesting.

When harvesting, grasp the tomato firmly with one hand and the stem with your other, twist at its stalk then place gently on your storage crate or container.

Tomato harvesting tips

  • Tomatoes are climacteric fruits. They will continue to ripen after detachment from the plant.
  • You can hasten the ripening process by enclosing the tomatoes with a paper. Enclosing will increase the concentration of ethylene, the ripening hormone.
  • You can slow the ripening process by storing the tomatoes in a cool and dry place.

Tomatoes rarely lack market. The prices, however, vary with availability and season. You can supply to processing firms or find brokers that can link you to external markets in other counties. Another option would be to market through online platforms like Kilimogram or Facebook.

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