Vegetable seeds will germinate with or without soil. All they really need is an infusion of water to swell the seed coat, and sufficient warmth to signify spring. In fact, seeds for our most commonly grown food crops are among the easiest to start. They will begin their growth on a paper towel, a bed of agar, or even while still inside the fruit where they were formed! The home gardener can put this fertility to good use.
Germination may take several weeks in cold spring soils, but once a seed has broken its dormancy, it will continue to grow. Taking advantage of this, I usually sprout my pea seeds on damp paper towels. This requires careful monitoring, as I don’t want the emerging roots, which are extremely brittle, to break. As soon as the root emerges from each pea, I carefully sow the seeds outside. They go about two inches apart and two inches deep, covered with fluffy soil or vermiculite. It’s nice, but not essential, to point the roots downward into the earth. Since they have already started to develop, the baby seedlings break the soil in just a few days.
I treat corn in the same way, scattering some seeds across dampened paper towels. Rolling them up together, I seal them into a plastic bag, which I check daily. A little warmth helps… corn will sprout faster at about 75 – 80º F.
With our extremely short and cool growing season, the jump start I get from pre-sprouting corn often makes the difference between watching undeveloped ears succumb to fall’s first frosts, and harvesting a crop.
Carrots and parsley, with their tiny seeds and long germination times, make good candidates for pre-sprouting on a layer of gel. While commercial mixes are available, a simple cornstarch base works fine. Mix a cup of water with a tablespoon of cornstarch. Heat, stirring, until the mixture thickens. Pour into a flat pan such as a pie plate and let set. Then sprinkle the seeds on top. Make sure there’s a bit of space around each seed. Cover with a piece of plastic wrap or a pane of glass to hold in moisture.
Within a few days, roots will begin to emerge from the seeds. Again, don’t let them get too long. If you break off the growing tip, the seedling will die. As soon as I can see the seeds are growing, I plant them. Take the pan outside and scoop each seed out with a small spoon, dropping it, along with its surrounding gel, into a hole about a half-inch deep. A covering of vermiculite makes it easier for the tiny leaves to break through the soil crust. Seedlings should appear within the week, as opposed to three weeks when planting seeds straight from the packet.
Our erratic spring weather can go from cool and damp to hot and windy in a matter of hours. Keeping seed beds damp for three weeks is challenging, to say the least. I have significantly higher germination rates when I plant pre-sprouted seeds, each encased in its own wet glob of gel.
Another advantage of pre-sprouting carrots is that it eliminates a lot of tedious thinning. You already know that the seeds you are planting are viable. Therefore, you can space them precisely where you want them. I usually plant carrots about four inches apart in all directions, across a four-foot wide bed.
Beans, on the other hand, are not a good candidate for pre-sprouting. Because of their huge cotyledons full of starch, germinating beans are extremely susceptible to cracking. It’s much safer to just plant them while they are hard and dry, and let them do their growing safely underground.