A definite sativa?? I topped mine once and i may do it atleast 2 more times it lets the under growth catch up and you will hopefully get a nice bushy plant. I got one nice bushy warlock plant you may of seen in my thread. Both the Green Crack and William's wonder are looking right good is the Green Crack turning purple at all for you?
As mentioned upthread, the original Green Crack is basically an F1 hybrid between an old school Skunk (sativa) and a California indica. Sickmeds version is an S1 of that, so its effectively Green Crack x Green Crack, or an F2 of the original parents. Consequently the plant should be expected to throw off a variety of phenos, some more sativa-like and some more indica-like. . .and by all accounts it does.
With respect to your question, THIS plant is a little unusual. It started off with an indica leaf and overall plant structure, and then after flowering the leaves and plant structure turned more sativa-like with lots of stretch and branch development. I asked the breeder about this, and he told me that this particular growth pattern is common in the S1 plants.
Because the breeder suggested growing as a single-cola, I didn't "top" this plant. Despite that, the lower branches "caught up" so to speak, all by themselves by stretching during flower, and although I started with a "stick", I ended up with a "bush"!
On color, yes, the "Green" crack is most definitely turning purple; and I'll have a few pictures up to show this as the journal progresses. You can see a "teaser" here:
https://www.rollitup.org/general-marijuana-growing/611353-post-your-purple-pics-2.html#post8527159
I think this may solve one of the "mysteries" of Green Crack. The William's Wonder is the one that's "supposed" to turn purple, but in fact, its this Green Crack S1 that has. On top of that, every single account of Green Crack S1 I've seen mentions the tendency of this line to turn purple. Both Sickmeds AND Riot Se-eds' ad copy mention this explicitly, and Sickmeds has multiple pictures of the thing going purple. I've also seen several third-party grow reports mentioning that their plants have turned purple at the slightest hint of cold weather. Everyone is saying that the S1 line (which again, is basically an F2 of the parents) turns purple more readily than the original (F1) Green crack, which does NOT have a rep of going purple.
If you think about this genetically, the F2s (ie Green Crack S1) "should" tend to throw off phenos that are more similar to the original parents, compared to the F1 (original Green Crack).
Anyway, since Green Crack S1 tends to turn purple, its a pretty safe bet that one of the original Green Crack parents tended to go purple. Skunk #1 isn't known for that. By elimination, the other parent, the "unknown California indica" has to be the one that turns purple. So which CA indicas turn purple?
The most obvious candidate for a parent is the famous Mendocino(/Humboldt) purple. This potent inbred CA indica line goes by different names, and has been grown outdoors as an "heirloom" strain up North in CA for at least thirty years. Its also a parent of most of today's "hot" purple lines including purple urkle, grand-daddy purple, etc. Notably, this strain was especially popular in the late 1980s and early 90s when the original Cush (later renamed "Green Crack") was created, and before there was a big proliferation of other purple strains.
Add it all up, the description of a "california indica" as one parent, the purple color seen in F2 plants, the time frame, and the overall quality of the line, I think its a pretty good bet that the "unknown parent" of Green Crack is this original famous CA purple strain.