The interior of a greenhouse. You can see trays of seedlings and herbs stretching from the foreground to the background. Photographed on a commercial organic farm. These seedlings are transplanted to fields once they are large enough. [Photo: Getty Images]

Ever heard of seedling tray? It is a modern way of gardening. This technology guarantees fast and large volume production of seedlings. Profitable vegetable production starts with good quality, healthy seedlings. Studies show that crops such as tomatoes, sweet pepper, lettuce and eggplant produce quality crops with the highest yield if they are first sown in seedling trays and then transplanted into the field.

There are many advantages of seedling tray. The seedlings are easily removed from the tray for transplanting and therefore increasing survival rate when planted in the field compared to the use of other types of transplants.

Additionally, compared to traditional seedlings, tray seedlings have a shorter growing season, the system also has improved crop uniformity and more accurate prediction of harvest date.

Seedling trays facilitate the use of a wider range of herbicides and are more efficient while growing hybrid seeds which can be expensive compared to traditional ones. Done properly, seedling trays cushion your seeds against fungal diseases common in the conventional method.

How to use seedling trays

The seedling tray is filled with the growing medium preferably coco peat. This is because it reduces the incidence of seedling diseases and contains right amount of moisture in it. A small depression is made with fingertip in the centre of the cell of the tray for sowing. Coco peat has a high moisture content and therefore no immediate irrigation is required until after germination. The trays are stack up to 10 trays one over the other for three to six days. The stack is then covered using polyethylene sheet to conserve moisture until germination. To prevent etiolation, the stacked trays are spread once the germination starts. Irrigate the trays lightly. Avoid applying too much water as this may cause disease attack. Drench the trays with a recommended fungicide to control diseases.

Nutrients

The planting media is mixed with lime, gypsum, fine grade superphosphate, a trace element mix and small amounts of nitrogen and potassium. A fine grade slow-release fertiliser may be used instead of adding N.P.K. separately. Only enough nutrients should be added to the mix to obtain steady growth for the first 7 to 14 days.

Further growth is maintained through foliar feeding with a soluble complete fertiliser every seven to 10 days until the seedlings are near maturity. Do not use fertiliser higher than recommended rates. Systemic insecticides are sprayed 7 - 10 days after germination and before transplanting for managing the insect vectors.

The seedlings would be ready in about 21-30 days for transplanting to the main field depending on the crop. Water plants with care because over-watering can easily leach nutrients out of soil-less mixes. Careful leaching of nutrients can be used as a growth control aid. Slowing seedling growth by this method is preferred to trimming the leaves of plants or with-holding irrigation before transplanting.

To obtain maximum benefits from the trays, good nursery hygiene is essential. Planning is essential to maintain nursery hygiene and to ensure a high standard of plant health. A seedling nursery must be clearly separated from any other growing system or area and there must be strict control over entry to the nursery to limit the possibility of introducing pests and diseases. In other words, a nursery must be treated as a quarantine area, with restrictions on entry and movement inside the boundary. This applies to people and materials or equipment. The seedlings at right stage of planting are hardened by withholding irrigation and reducing shade before transplanting or selling to grower


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