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| Speedwell (Veronica officinalis) as a Ground Cover |
Answered by: Conrad Richter
Question from: Mary Lou Kirby
Posted on: May 15, 2002
[Voice mail question about growing speedwell as a ground cover on the edge of a forest in Orillia, Ontario: how much seed is needed to plant an area of 600 square meters.]
Speedwell is naturalized in some parts of Ontario so we know that it can grow in your area. It thrives in sun or partly shaded locations so it can do well along the edge of forests where the shade is not too dense.
We do not recommend direct sowing of the seeds over the area as you want do with grass seeds, for example, because the seeds are tiny (over 7000 seeds per gram) and expensive. We recommend indirect sowing in seed flats or plug trays. You will need to raise the plants until they are large enough to withstand outdoor planting.
If you sow in plug trays and you don’t sow too thickly, you can raise the seedlings in the plug trays until they are ready to transplant outdoors. The trays can be germinated and raised outdoors now during the warmer spring and summer months.
If you sow in a seed flat (a plug tray has many cells; a flat has no cells), then you will have to transplant the seedlings to another flat for growing on. You can germinate the seeds in the flat and raise the seedlings until the 4-5 leaf stage and then transplant to a new flat, 50-100 seedlings per flat.
Sowing in flats is more efficient you need less seed to cover the same ground; about half a gram for a thousand plants. If you sow in a 128 cell plug tray, you need 10-15 seeds per cell, or about a gram for a thousand plug cells.
To plant 600 square meters you will need to plant out 25 plants or plugs per square meter. That means you will need 15,000 plants or plugs. To produce that many you will need between 7.5 grams and 15 grams depending on which method of sowing you choose.
It is not impossible to sow directly over the area. But the bed has to be very well prepared with a finely raked surface, free of weeds, roots and debris. You will need about about 50 grams of seed, which should be mixed with a carrier like dry sand to help you to spread the seeds more evenly. You should moisten the bed before sowing, wait until the area is not too muddy to walk over it and then sow. Only tamp down to avoid planting too deep. The tamping down will be enough to press the tiny seeds into the soil and give them a soil cover. Once tamped down give a light watering to make sure the seeds are well lodged in the soil.
The biggest challenge will be to keep the weeds down while the seedlings become established, which is another big reason why we prefer indirect sowing over direct sowing. The seedlings will appear as early as 5 days and can take as long as 30 days to come up. Once up, it will take a good season or two of hand weed control until the patch is well enough established to compete against weeds.