Starting seedlings for hydroponics is easy and can be achieved with a minimal investment in time and money. You will need a tub of ice cream, a knife or scalpel, rockwool seedling cubes either cut from a slab or purchased already cut to size and of course some seeds of the plants you would like to grow. For our example we are going to germinate some capsicum seeds. The first step is to eat all of the ice cream and then wash the container thoroughly so it can be used to keep our rockwool moist.
Get Seedling Cubes
As previously mentioned you can buy rockwool seedling cubes that are precut like the one in our image to the right of this paragraph. It is more economical to purchase large rockwool slabs and cut slices off it to make your own seedling cubes however this is completely up to you to decide. The seedling cubes should be soaked thoroughly in fresh water for a few hours and then rinsed prior to use to remove any built up salts from the manufacturing process and to make sure they are wet right through. Seedling cubes already have holes in them but the are rather small and more suitable to cuttings. Use your knife to make the holes bigger in diameter and as deep as the planting depth specified on your seed packet for the plants you are growing.
Place Seed in Seedling Cubes
Place one seed into each hole in your seedling cubes. Once you have a seed in each hole of the seedling cubes gently place them into the ice cream container and fill it with plain water until it reaches about halfway up the rockwool seedling cube. This will provide the initial moisture that will trigger the germination of the seed. Allow the water to evaporate to the point where the bottom of the ice cream container is only just covered and then top it up to halfway up the seedling cube if the seedlings have not germinated at this point.
Once your seedlings have geminated keep them moist with fresh water or fresh water and superthrive. Once the seedlings first set of leaves are open start watering them with 1/2 strength nutrient solution for a week or so or until they have become established and start growing. Once they are well established you can start using full strength nutrient solution on them, making sure they remain moist. They can be planted in your hydroponics system at any time after they have become established and start growing however you may elect to keep them growing in the ice cream container until they are reasonably advanced.