Planted strains that were compatible in duration: both Purple Punch and Gelato XX are marked as 60-65 days flowering time. I'm aware they might take longer than that, or they will develop differently but for now I wanted to make sure they're compatible to grow together.
Later edit: the Gelato XX seed did not germinate and I didn't have more. The first Purple Punch seed went into soil on Oct. 22nd and sprouted on Oct. 26 (day 5 from planting the seed). Planted a second Purple Punch on Oct. 27 and it sprouted on Oct. 30 (day 4 from planting the seed).