Starting with healthy seedlings is critical for hydroponic crop production. The key considerations are:
• Start with high-quality seeds
• Use sterile, pH-adjusted growing media
• Provide appropriate levels of water and light during propagation
Hydroponic growers have a number of options available to them for starting their seedlings, ranging from simple homemade manual systems to more automated, higher-tech propagation systems -- including Aeroponic cloners, Nutrient Film Technique (NFT) trays and Flood and Drain trays. While the lower tech systems require a higher degree of attention on the part of the grower, they can be used to produce high-quality seedlings for transfer into a hydroponic growing system.
Prepare Your Growing Media
Place media cubes or prepared pots on nursery trays with a webbed or slotted bottom. Keeping the cubes connected in a block will make them easier to handle.
Thoroughly soak your growing media with pH-adjusted water. Immerse the flat in a container of pH-corrected water. Oasis, coir and perlite should be soaked in water with a pH of 6 to 6.5. Important: Rockwool must be pre-soaked for 24 hours in water adjusted to a pH of 5.0.
Drain the cubes or pots thoroughly.
Insert Seeds into the Growing Media
Check the cubes for pre-drilled dibble holes. If there is no hole, make a ¼-inch deep hole in the surface using the sharp end of a pencil or a pointed tool.
If you are using loose media, use a pointed tool to make a 1/4-inch deep hole in the center of the pot.
Place the seed in the dibble hole. Larger seeds, such as cucumbers or sunflowers, can simply be pressed down into the media until they are covered.
Cover the seeds with a thin layer of vermiculite.
Water the top of the media gently with a sprayer to settle the seeds into the media.
Drain excess water from the trays.
Cover the media with a humidity dome or another tray to create a high-humidity environment.
Place the trays away from direct sunlight in a location that can be maintained at a temperature of 70 to 75° F.
Check the media once a day and water or mist as needed to keep the media moist.
When the seed coat has cracked and the radical (root) has emerged, remove the dome and expose seedlings to full light. This can be sunlight or artificial light. Most seedlings will grow well 4 to 6 inches away from fluorescent lights.
Seedling Emergence and Transplant
Once the seedling has emerged, continue to water it as needed with a half-strength solution of complete hydroponic nutrient.
As soon as leaves of seedlings in adjacent cubes or pots touch, increase the spacing between them.
Separate starter cubes from the block, using a knife. Take care not to damage the roots when handling the cubes.
Seedlings can be transplanted into the hydroponic growing system when they are 2 to 4 inches tall.