Tall sprouts don't mean a lot, really. I've got a 75% indica (Citral) that sprouted high. I have another 75% indica (Top44) that sprouted low as hell. To further confuse, one has fat leaves, one has skinny. With mixed genetics these days, you never know what the leaves will look like. The last time (besides now, 9 years ago) that I grew, I popped up a pure Mexican Sativa from a bag of the schwaggiest bullshit ghetto-bud brick bag ever - delivered in truck tires from Mexico! It grew strong and high FAST AS HELL. A month in, it was 3.5 feet tall with a very thick, sturdy stem. It had skinny leaves. Unlucky for me, it was male. 19 days into my current indica grow, my babies are about 3-4 inches tall. If you have a heavy sativa, it should take off. Not uncommon to see 10+ foot sativas.