Agronomist notebook: All you need to know on caring for seedlings

Women graft seedlings at a tree nursery in a farm in Kisumu County.

Women graft seedlings at a tree nursery in a farm in Kisumu County. When setting up a tree nursery, always understand the climatic conditions of your locality and the soil as this would determine the kind of a nursery to set up. PHOTO | ELIZABETH OJINA | NATION MEDIA GROUP

What you need to know:

  • Always handle seedlings carefully to avoid stem breakages or injuries that act as entry points for pathogens
  • It’s vital to add well-rotten manure and incorporate it with the soil as this ensures the seedlings are healthy, thus reducing the chances of top-dressing them.
  • Also, a raised bed helps in controlling soil erosion on the nursery bed as the paths along the beds encourage the drainage.
  • Nursery hygiene should be observed by collecting all the waste and disposing of it properly, as this prevents the introduction of pathogens to the plant.

Norah, a farmer based in Kiambu, sprayed urea in the morning to improve vegetative growth of her onion seedlings.

After a few days, some of the seedlings were scorched and upon checking the nursery bed, the moisture content was low.

She was watering once per day – in the evening, which contributed to the problem. Seedlings are very delicate, hence it’s vital to be careful while carrying out management practices such as fertiliser application.

For instance, urea has 46 per cent nitrogen, which has high scorching effects, especially when applied on the leaves.

To avoid the scorching, make furrows or drills on the nursery bed, apply the fertiliser and cover with the soil. After this water the nursery bed immediately to increase the plant absorption rate.

You should also consider applying fertilisers formulated for use in seedlings production to minimise the chances of scorching the young plants. 

Always read the product label to ensure you use the correct rates as recommended by the manufacturer.

It’s vital to add well-rotten manure and incorporate it with the soil as this ensures the seedlings are healthy, thus reducing the chances of top-dressing them.

Seedlings are also affected by pests and diseases, hence the need to prevent and control them.

The use of chemicals should be the last option after exhausting all the cultural and biological methods of pest and disease control.

Understand the climatic conditions of your locality and the soil as this would determine the kind of a nursery to set up.

For instance, a farmer in semi-arid area should consider setting up a sunken bed, as this would help in conserving soil moisture and reducing water usage. 

Sunken beds are slightly below the general ground level, making it easy to irrigate during the dry season.

CONSIDER THE WATERING PATTERN

In highland areas, one should consider setting up a raised bed as this would help in drainage. 

Also, a raised bed helps in controlling soil erosion on the nursery bed as the paths along the beds encourage the drainage.

If growing greenhouse crops on a large scale, consider setting up a propagation unit as planting seedlings from the open field in the greenhouse may result in the introduction of pests and diseases inside the structure. 

While raising the seedlings, consider the germination percentage as this matters in the plant population of the crops to be transplanted. Check on the seeds label to see the germination percentage of the seeds.

Once the seeds have germinated, consider the watering pattern as excess water results in damping off, a fungal disease that affects young seedlings.

Also, when using growing media such as coco peat and peat moss, excess watering results in the growth of mould, a green colouring matter at the base of the plant.

They are living organisms that also compete for the nutrients supplied to the plant. They also attract the fungus gnats, a flying pest whose larva feeds on the plant roots, affecting the rooting system of the crop. 

It’s thus important for the farmer to consider the watering regime of the crop, which depends on the weather conditions and the soil moisture content. If the soil is wet, avoid watering.

Ensure that seedlings receive sufficient light to prevent them from developing tall thin stems.

If the temperatures are too high especially during the dry season, consider erecting a shade net as excess heat can cause rapid growth, making the stems grow faster than the leaves.

Nursery hygiene should be observed by collecting all the waste and disposing of it properly, as this prevents the introduction of pathogens to the plant.

While carrying out all the management practices, always handle the seedlings with care to avoid stem breakages or mechanical injuries that act as an entry point for pathogens.

Under good management practices, most seeds are ready for transplanting after four weeks in the nursery. 

They usually have three to four  mature leaves and about 15cm tall.  Avoid transplanting unhealthy and weak seedlings this increases the cost of production.