This archive report was first published on 3 August 2019.
Published on August 3, 2019, a farmer from Narok shared his struggles with poor germination rates of his seedlings, resulting in significant losses.
He had invested Sh12,000 in half a kilo of onion seeds, expecting to grow them on a half-acre plot. However, the seeds only germinated enough to cover a quarter-acre due to low germination rates.
Many farmers face similar challenges with seed management at the nursery stage. To overcome this, good nursery management practices start with selecting an ideal site that is secure, has a slightly sloppy land for drainage, and is near a water source.
The site should also have fertile soil, taking into account the previous crop to prevent the spread of pests and diseases. In highlands, a raised bed encourages aeration and drainage, while in dry areas, a sunken bed conserves soil moisture and protects seedlings from wind.
A nursery bed should not exceed one meter in width for easy access, and the number of seeds sown determines the length. The bed is prepared by clearing the land, double digging to break hardpans, and removing stumps and roots.
Well-rotten manure is added at a rate of 2kg per square meter and thoroughly mixed with the soil. Levelling is done, and furrows of 2cm deep and 15-20cm apart are made across the bed.
Seeds are sown singly in intervals of at least 2cm, with an average of 50-60 seeds per furrow. Before sowing, the farmer should calculate the number of seedlings required to avoid over or under-sowing.
For example, an onion farmer planting 60 plants per square meter on half-an-acre with an effective growing surface area of 1,500 requires 90,000 seedlings. Considering the germination percentage and succession rate of 20%, the farmer should plant approximately 108,000 seeds, equivalent to half a kilo.
After sowing, the seeds are covered lightly, and mulching is done to prevent splash erosion. Mulching materials should come from a reliable source to prevent the introduction of pests and diseases.
Watering starts immediately after applying the mulch, with two waterings per day depending on weather conditions and soil moisture content. Once 70% of the seeds have germinated, the mulch is removed to prevent seedlings from developing weak stems.
Depending on weather conditions, a shelter may be erected to protect the seedlings. Other management practices include preventing pests and diseases, weeding, and hardening off, which involves adjusting the watering regime.
For example, if watering twice a day, reduce to once. If a shelter has been erected, remove it in the morning hours and replace it in the afternoon when temperatures are high, until the seedlings are ready for transplanting.
Hardening off allows seedlings to adapt to environmental conditions in the open field, reducing transplanting shock and loss. Seedlings are ready for transplanting after three to four weeks for sukuma wiki, spinach, and cabbages, while onions and capsicum take six to eight weeks depending on the variety.
During transplanting, the nursery bed is wet to ensure seedlings come off with a lump of soil. For greenhouse production, use trays and soilless media like coco peat and peat moss to produce seedlings free of soil-borne diseases.
