I always figure 85 percent is good, at least for most seeds. Some things - peas, corn, lettuce, carrots - I'm sure they are lower.

IME, the most important factor is the potting mix. Too coarse, too fine, inability to hold moisture, holding too much moisture - they can be real detrimental. Too much heat can cook the seeds, but 72 is not too warm or too cold. Covering the plants with too much mix can either delay germination or even keep it from happening.

Plus, there the seeds themselves. I bought 100 Bhut Seeds and got about 18 seedlings, not good. The purveyor sent me another 50 (free!), I sowed 18 and 17 of them germinated.

From another place I bought Jalapeno, Habanero, Hungarian Hot Wax, Cayenne and Tabasco seeds. All except the Tabasco had at least 85 percent germ, the Tabasco - one of 24! They were all sown in the same tray, watered exactly the same and experienced the same temps. This is why I tend to sow more seeds than what I need.

Mike

I agree with Mike. I do like my temp a little higher than 72 though. I prefer 78-80. I got some seeds in the fall (only 10) for sungold select tomatoes and only got 1 sprout. The vendor stated 85% lol. I had just wanted to do a germination test but used them all just to get one. I grew it out inside and saved seeds for spring planting (which is just about here).
Mike I've got plenty of tabasco seeds if you want some. I can almost guarantee you get better germination from mine. They are fresh from last year.