How to Grow Plants Hydroponically from Seeds

Many hydroponic gardeners prefer to grow plants hydroponically from seedlings or cuttings taken from another plant – often from a plant grown in soil. While you can get away with this, it does introduce a host of problems that don’t exist when growing from seeds.

The advantage of hydroponics is that you can produce higher yields than soil grown plants and your plants don’t suffer from the same pests and diseases that can afflict soil grown plants. Seeds do not contain the pests and diseases found in seedlings. If you purchase seedlings from a plant nursery where disease and pests are common you risk infecting your hydroponic garden and ruining your plants. Aphids are often found in plant nurseries and they are difficult to spot.

Purchasing a seedling involves rinsing the roots to remove the soil before they can be transferred to a hydroponic solution. Some plants do not take well to being transplanted from soil to a hydroponic medium which creates stress on the plant and hinders growth.

If you want to get the satisfaction that comes from growing from seeds and entirely through your own efforts then you will require the following kit:

  • Stonewool plugs
  • Hydroponic tray
  • Warming Mat
  • Grow light or natural light if it is available
  • Seedling solution

Growing tiny seeds in granular hydroponic media will simply result in the tiny seeds falling through the cracks when they are exposed to a hydroponic solution. Starter plugs should be made from inorganic material, be approximately 2 or 3 inches across and shallow enough so the seeds are never far from the nutrient solution which keeps them moist. Rockwool plugs are ideal for this purpose.

Simply use a pencil to make a number of holes in each starter plug. For most plants 2 seeds per cube should work, but for herbs 4-6 seeds per cube is more appropriate. Place each of the starter plugs into a slot in the hydroponic tray to hold them in place. This tray is where you will add the hydroponic solution.

Place a clear plastic domed shaped lid over the tray. You can buy a hydroponic propagation dome that is specifically made for seedlings. Some even allow you to adjust the humidity with adjustable vents. The container needs to hold in moisture and heat the air around the plants. It also needs to be transparent as seedlings require abundant light to grow.

A seedling heat mat can be placed underneath the tray to ensure the seedlings are kept warm. A temperature of between 70 to 80 degrees Fahrenheit is ideal. Depending on how quickly the tray dries out, the seeds will need to be watered once or twice per week. You should add seedling solution to the tray but not directly on top of the plant. The pH level of the hydroponic solution should be around 5.5. It should also contain the necessary macro and micro nutrients found in most hydroponic nutrient solutions.

The seeds should start sprouting in 2-3 days and within 1-3 weeks the plants should be a few inches high. The roots should also be visible from the outside of the starter plug. Leave the strongest seedling in a single plug and remove the less healthy ones. When the roots start to show through the plugs it is time to transfer the plants to a larger unit. Do not remove the roots from the starter plug, just place the plug inside the hydroponic unit.

Make sure the seedlings are kept moist and that the roots have access to the nutrient water solution. It is also important that the growing plant be exposed to plenty of light as it matures so supplement it with grow lights if adequate natural lighting isn’t available.

Simon Ashley is an avid home hydroponic grower.

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