I don't know! Really, I don't know! My tomato starts are horribly small. That may be a comparative thing having seen the size and vigor of the local farm stores $1 tomato plants. Additionally, the local Master Gardener's sale is coming up, again, $1 beautiful plants. I've tried over the years to be more self-sufficient by growing and even selling my own starts along with growing heirloom varieties so the seeds would be true to type. I blame the soil for my lousy starts but.... In my Denver garden I was able to simply fill pots with some of my compost add the seeds and cover them with a 1/4 inch of commercial organic seed starting mix. Since moving here I've been busy terracing the south-side of our house with raised beds and filling them with anything that vaguely resembled soil. When time came to start seeds there wasn't even a smidge of half finished compost to be had. Yup, I admit it I bought a bag of that crap they sell at Lowes. Or in my best Clintonesque...