How To Grow From Seeds
by Lana Kenan
WHAT IS SEED STARTER SOIL?
Initially, seeds don’t actually need any soil. Everything the seed needs is already in the seed so seed starter soils don’t usually contain any fertilizer. Too much nutrient in the seed starter soil can harm delicate seedlings. After the seed has germinated it will need a finer and lighter soil for the tender young roots to navigate and spread. Seed starter soils are therefore designed to help seedlings become established before they are transplanted to a coarser potting mix or garden bed where the seedling will have access to nutrients.
MAKING SEED STARTER SOIL
- Start with 2 parts compost that has been sieved.
- Now add 2 parts coir (coconut fibre). Coir is extracted from coconut husks, making it a sustainable, plentiful alternative to peat or peat moss. Extracting peat damages fragile ecosystems and contributes to climate change. If your coir has come in a block, rehydrate it first by soaking it in a bucket with water until you can easily break it apart. If you prefer, you could substitute well-rotted leaf mould in place of the coir. Both coir and leaf mould contribute bulk to the seed mix, and are great for moisture retention.
- Finally, add one part perlite, which will both lighten the mix and improve its air content. If you prefer not to use perlite then you could substitute sand, though it will give a heavier mixture.
Take your time when mixing the soil. The consistency needs to be even. Once mixed you can store the soil in a lidded container or a strong plastic bag with the top rolled down tightly and secured.
USING THE SEED STARTER SOIL
Moisten the seed starting mix before you use it, so it’s damp but not sodden. Gently press down your seed starting mix as you fill your container, and take particular care to properly fill at the corners. Top up with more mix if required. Don’t worry, this mix isn’t easily compacted so don’t be shy about firming it down so there’s enough mix for roots to explore.
PLANTING THE SEED
There are many factors that help a seed to germinate. Soil temperature is a main factor. A good location, warmth, water and indirect sunlight. Soil is not an important consideration at this time. Giving the seed a good location means planting the seed at the depth recommended by the packet instructions. It also means that watering can be tricky to avoid moving the seed with a blast of water. Gentle watering, sometimes twice a day, will help keep the soil moist, but not wet. Warmth can be supplied by covering the seeds with a plastic cover or using a heat mat. Choose a position that gives the seed plenty of light, but not direct sunlight.
WATER FROM BELOW
Commercial growers prefer water from below rather than using sprays. Watering from below offers the most effective and reliable method to water seedlings. Watering from below relies on capillary action (wicking of the water through the soil from the bottom working its way up to the top). Watering from below prevents any soil disturbance while watering. You also get the added benefit of not damaging the seedlings. Place seed in a shallow tray filled with water to water from below - only a few cm of water is needed.
IDEAS FOR SEEDLING COVERS
To stop some plants from getting too much water, or to give some seedlings extra warmth, you can cover them with plastic drink bottles that have the bottom cut out. Clear plastic drinking glasses work too if bottles are too big. For larger covers you can use plastic containers turned upside down. Cling wrap is good for newly planted seeds.
TROUBLESHOOTING
Seeds won’t germinate. - Some seeds take longer. Be patient. Has the seed been planted too deep? Is it getting enough water, sunlight and warmth? Did you plant at least 2 seeds in case a seed is a dud? Did you plant at the right time of year?
Seedlings fall over and die after sprouting or there is mold growing in the seed tray - This is called damping off, and is caused by bacterial seedling blight. Solutions. Use the correct soil for growing seedlings. Wash all pots, trays and tools before you use them. Check that there is enough ventilation. Remove plastic covers from seedlings once they have germinated and check that there is enough circulating air in the growing area. Water plants from the bottom rather than the top and do not overwater. Soil that is too wet can grow bacteria. Check that the seedlings are getting enough light and that they are not overcrowded.
Seedlings turn yellow, brown, or have faded leaves - This is caused by overwatering (water from below). Another problem with overwatering is that the wet soil can attract insects like fungus gnats. If you do get insects around the seedlings hang yellow sticky paper to help control pests. Wrong soil (use proper seeding soil). Fertiliser burn (seedlings should not be fertilised). Sunburn (move plants away from direct sunlight). Plants should be introduced to direct sunlight gradually - take them outside in the sun for only a few hours each day, gradually increasing the length of time until they have been “hardened off” before transplanting.
Weak, leggy seedlings - Not enough light. The seedlings are growing leggy because they are searching for more light. Relocate the seedlings so that they are getting more indirect sunlight. If the plant gets too leggy and falls over, it is probably too late to save it. Overcrowded seedlings will compete for light by growing leggy. Move the seedlings further apart so that all the seedlings are getting enough light.
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