The Winner Is: Heat Mat – seeds slightly covered with soil.
In three days the gomphrena on a heat mat germinated. Five of six have germinated. It also appears that the seeds slightly covered seemed to look at bit better. Only two of three seeds left on top of the soil have germinated at this point. Note that since I only have one heat mat, I had to put the seed pack on top of milkweed seeds that were on the heat mat.
Note – I’m also trying to simulate the heat mat by using lights directly on top of the plastic cover and filling the tray with 1/4″ of water. The water should absorb the heat and help create the heat mat effect –
Results – heat only got to 73 degrees.
Here’s my original test below.
Gomphrena or Globe amaranth is a great butterfly nectar plant for the smaller butterflies, but I find that it’s not an easy seed to germinate. In one case I planted 500 seeds and got one to germinate.
Here are the tests I’m doing. I’m getting different advice from various websites.
Planted Seeds March 5th.
1. Soak seeds for 24 hours prior to planting.(some sites say 24 to 48 hours) 6 seeds on top of soil and 6 underneath soil.
3. Gomphrena is a bit difficult to grow from seed. The seeds should be sown indoors in February in a container with bottom heat. Tried some on top and some under soil.
4. Standard planting of seeds.
Here are notes from the Seed Germination book.
“A few species germinated better at temperatures in the range 90-100 or after brief exposures to even higher temperatures
“G. haageana germ best (91% in 2-4 d) in a regime of 90 daytime and 70 nightime temperatures. This supports a report from Ralph Cramer (a commercial grower of Gomphrena) that the seed germ. best if given 4 d at 100 and then shifted to 70. Germination was poorer at a constant temperature of 95(70% in 4-15 d) and even less at 70.”