Well, it's that or wait until about July 1st to sow outdoors here. Our base soil simply warms too slowly to start any earlier. Now, if I were to sow these in the best beds (that warm earlier) instead of just filling out bare spots in the yard it might be a different story as far as the germination rates go, but I doubt they'd flower much earlier anyway. Seems to me I tried it before and the plants were really good sized, but the blooms still didn't open till fairly late in the season.
Zinnias that I started indoors, early 2013 started blooming in the veggie patch around July 1st, so I guess it would be possible to have two crops/plantings in a normal (hot summer) year if desired. Either way works, I guess, it's just a matter of how much indoor space we have available to work with in order to get earlier blooms.
