Plants are similar to children in that you have to give them lots of attention early on so they achieve optimum health and maturity later. At the germination and seedling stages, plants need proper amounts of nutrition, light, warmth and oxygen. This enables them to develop the strong roots, thick stems and dark green leaves that will produce an abundance of quality flowers and vegetables. A healthy start is essential.
Use the Correct Seed Starting Soil Medium
Soil preparation is one of the most important ingredients in growing strong plants. At the most basic level, the best medium for germination and seed starting is one that provides excellent nutrition, good drainage and good moisture retention. A sterile soil with amendments or a soil-free mixture is recommended for most seed starting.
It is possible to use soil directly from your garden for a growing medium, but it might contain fungus, insects or weed seeds that could sabotage germination or kill young plants. To stop this, you can sterilize your soil by heating it in the oven for a half hour at 250 degrees. Garden soil also has a tendency to be too dense. What you really want is a medium that is loose and aerated for strong root development. If you plan to use garden soil, add peat moss plus sand or vermiculite for aeration and water retention.
Soil-less mixes are readily available at garden centers. Most of them consist predominantly of sphagnum peat moss with bark, coir, perlite, vermiculite and maybe some traces of nutrients. Since peat is generally very acidic, you might want to consider adding a bit of lime to help neutralize the mix.
The bottom line on the soil medium, however, is to choose the mixture that is most ideal for the seeds you’re germinating. Read the seed label carefully, not just for soil type, but for PH level, nutrient, light and water recommendations.
Warm the Soil for Starting Seeds
Seeds don’t always need light for germination, but they do need warm, moist soil. For most seeds, soil temperature should be a consistent 75 degrees. This can be achieved by placing seed trays near a heater, or on top of a refrigerator. You can also use special seedling heat mats, purchased from the store, which have a thermostat to create an even flow of heat throughout the germination period. Once you see sprouts, however, you should immediately move them away from the heat to keep the plants from growing too fast and leggy.
Soak Seeds for Faster Germination
Most seeds germinate with ease, while others require some coaxing. To speed up the germination of seeds that are old or have a poor germination rate, you can try soaking them.
- Scratch the surface of the seeds with a sharp knife, a pin or a piece of sandpaper. This will allow them to soak up water more quickly.
- Place the seeds in a shallow pan or bowl of water that is warm, but not too hot, to the touch.
- Add a drop of liquid dish detergent which helps to reduce the surface tension of the water, allowing it to penetrate the seeds even more quickly.
- Soak the seeds overnight.
- Plant the seeds in your potting medium right away or keep them on a damp paper towel until you’re ready.
With this method, it’s possible to reduce the germination period from a couple of weeks to a matter of days.
Pre-Sprouting Seeds
Seeds can also be pre-sprouted, or chitted, to hasten germination and help you determine the quality of your seeds.
- Mist a sheet of paper towel with a spray bottle of water, until it is slightly damp.
- Sprinkle seeds on one side of the sheet in a single layer. It doesn’t matter if they touch one another.
- Fold the paper towel over the seeds.
- Place the paper towel into a plastic bag, but do not close the bag.
- Mist the paper towel again until it is damp, but not soaking wet. Keep the paper towel damp until the seeds sprout.
- While waiting for germination, keep the plastic bag in a warm spot, about 65 to 75 degrees Fahrenheit.
- When most of the seeds have sprouted, transplant them into pots or directly into the ground.
Want to learn more about giving seedlings a head start?
See these helpful resources:
Plant Propagation from University of Arizona Extension
Propagating Plants from Seed from Pacific Northwest Extension
Sometimes my seedling pods get moldy in the top of the seed starter mix. What can be done about that
Increase air flow