Vegetables
Senior 1 · Agriculture
Vegetables
Lesson 2 of 5
22 min
Let's begin
One gram of tomato seed holds a few hundred tiny seeds, and a packet can cost more than a kilogram of tomatoes. Scatter those seeds straight into a rough field and most will be lost to heavy rain, drying sun, ants and weeds. Raise them in a well-kept nursery bed and nearly every seed can become a strong seedling.
Many young people in Rwanda earn money by raising vegetable seedlings in nurseries and selling them to farmers at planting time. This lesson shows how a nursery is set up and run.
A nursery is a small, specially prepared area where seedlings are raised with close care until they are strong enough to be transplanted (moved) to the main field.
Crops usually raised in a nursery: tomato, cabbage, cauliflower, kale, onion, eggplant, sweet pepper, lettuce. Crops NOT raised in a nursery: root crops (carrot, beetroot) and large-seeded crops (beans, peas, pumpkin, cucumber).
| Type | Description | Best for |
|---|---|---|
| Raised bed | Soil built up 15 to 20 cm above the ground | Rainy seasons and heavy soils: drains well |
| Sunken bed | Surface a little below ground level | Dry areas: holds water |
| Flat bed | Level with the surrounding ground | Well-drained soils with moderate rain |
| Containers | Seedling trays, pots or polythene tubes filled with a soil and compost mix | Valuable seed; seedlings move to the field with their roots undisturbed |
Seedlings are ready when they have about 4 to 6 true leaves and are 10 to 15 cm tall (for tomato and cabbage, usually about 4 to 6 weeks after sowing). Water the bed a few hours before, lift each seedling with a ball of soil using a trowel, and plant in the evening or on a cloudy day at the same depth, firming the soil and watering well.
Question: A nursery bed is 1 m wide and 5 m long. Drills run across the bed, 10 cm apart, and the seedlings are thinned to 2.5 cm apart in each drill. (a) About how many seedlings does the bed hold? (b) If 80% of them are good enough to transplant, how many can be planted?
(a) Number of drills along 5 m: 500 cm ÷ 10 cm = 50 drills.
Seedlings per 1 m drill: 100 cm ÷ 2.5 cm = 40.
Total = 50 × 40 = 2,000 seedlings.
(b) 80% of 2,000 = 0.8 × 2,000 = 1,600 seedlings.
Tip
Memory hook for nursery care: "Water, Weed, Thin, Protect, Harden", then transplant.
Exam technique: "hardening off" is a favourite question. Give both what is done (reduce watering, remove shade gradually) and why (to toughen seedlings so they survive transplanting).
Define a nursery and give three advantages of raising tomato seedlings in one.
Solution: A nursery is a small, specially prepared area where seedlings are raised with close care until they can be transplanted. Advantages (any three): saves seed; easier watering, weeding and pest control; only strong seedlings go to the field; the field can carry another crop meanwhile; a uniform crop.
Why is a nursery bed made about 1 m wide?
Solution: So that a person can reach the middle from either side for sowing, weeding and thinning without stepping on the bed.
Give two causes of damping-off and one way to prevent it.
Solution: Causes: overwatering (waterlogged soil) and overcrowded seedlings, which favour the fungi. Prevention: sow thinly, water carefully, ensure good drainage, or treat the soil before sowing.
Explain why transplanting is done in the evening or on a cloudy day.
Solution: The seedlings lose less water through their leaves in cool, dull conditions, so they wilt less while their roots re-establish.
A bed holds 1,500 seedlings and 90% are fit to transplant. How many is that?
Solution: 0.9 × 1,500 = 1,350 seedlings.
Summary
Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
