Enter sowing season 2012. The first seeds I planted were kohlrabi, lettuce, and spinach, and, as usual, I had a lot of trouble trying to distribute the tiny seeds evenly along the row. Since some of the seed was from last year, I wasn't sure of the germination and decided it was okay to just let the seeds go in as thickly as they came out of the packet.
Whether fortunate or unfortunate, those old seeds germinated very well, so I had to do a lot of thinning, one of the hardest parts of gardening for me. I have to pull out perfectly wonderful plants and toss them (or use the tiny leaves for an early nibble or even part of a salad) while trying not to dislodge or damage those plants that I am allowing to grow. As I carefully picked out some of the most prolific kohlrabi and lettuce, I was reminded of the seed tape idea and went on an internet search for more info.
Well. It may be a new technique for me, but it certainly has been done in many ways by a whole lot of people out there in the blogosphere, using all different materials....and having all different results, including several sites where it seemed no one had had any success with germination of their carefully prepared seed tape seeds.
As I read through these sources, it seemed as though a major problem, when there were massive failures, was that people were preparing these tapes a long time in advance and then storing them away for planting later. Some of the directions also involved pretty meticulous hand picking of the little seeds and lining them up on carefully placed dots of the "adhesive" of choice, making the work seem hardly worth the time.
Even more of a warning should have been the fact that I found no sites--not even one--where germination and final results were given. Lots of excitement about how kids could get involved in making the seed tapes, but none on how many plants actually came up.
I know my results are anecdotal, but they were dismal. I made the tapes and immediately transferred the seeds to the garden. At the same time, I planted a few rows with the same seeds but not on seed tapes. Results? Almost zero germination for the tape plantings and usual germination for the others.
I can't help but think this could be a very disappointing experiment for kids if their carefully prepared seed tapes don't result in happily sprouting seedlings. So my suggestion is to skip all these "cute" ideas for having kids making seed tapes. sorry.
(I am including the steps that I took in doing this, so that anyone interested in challenging my results has the facts they need!)
Seed Tape for the Garden
Cheap, single ply toilet paper (the kind that comes in single rolls, 1000 sheets each, works well)--try to avoid any added scent, lotion, softeners, whatever. You want plain old minimalist paper
Flour and water paste
1. Tear off a strip of toilet paper about 2 to 3 feet long. (Longer than this is harder to handle, so I suggest you do the seeds in increments if you have longer rows.) Fold it lengthwise in quarters, so you have a strip about an inch or so wide. Spread the strip out on a table or other flat surface. This will be called the "tape" from here on out.
2. Make a paste of flour and water: put a tablespoon or so of flour in a shallow bowl and stir in a little water at a time, until the consistency is just a little thinner than school glue. (This mixture will thicken as it stands, so you can start out just a little bit on the thin side.)
3. Using a small teaspoon, dribble a tiny stream of paste down the center of the paper. Your goal is to have a small sticky spot at each part of the tape without getting the paper so wet that it will tear or break.
4. Pour a small amount of seeds into a small cup or bowl.
5. Dip one end of a toothpick into the flour and water paste, just enough to moisten it. Then dip the toothpick into the seeds. One or a few of the seeds should stick to the toothpick so that you can then place them on the tape at intervals as needed for each kind of seed. You will probably not have to dip the toothpick in the paste every time, only when the seeds no longer stick.
6. When you have placed seeds the full length of the tape, lift it carefully by the ends and carry it directly to your garden row, where you have already prepared a trench. Lay the tape in the trench and cover completely with the appropriate amount of dirt.
7. Repeat with more sections of tape as needed to complete your planting.
I used this method with lettuce, kohlrabi, collards, cilantro, dill, and basil.