How Much Does Zkittlez Yield? Zkittlez produces yields of around 450 grams per plant when it's grown outdoors. When grown indoors, the strain can produce around 350 grams of pure bud per square meter. Is Zskittlez Difficult To Grow? Zkittlez is considered to be a moderately difficult plant to grow. Zkittlez is an incredible popular strain, especially in the US. In 2015 and 2016 she won prestigious cannabis awards.and it won't surprise us if there are a few more to come. Grow your own Zkittlez Grow difficulty Medium Flowering type Photoperiod Flowering time 8 weeks Harvest time (outdoor) October Yield (indoor) Medium Yield (outdoor) Medium. The average THC level is 21% in Watermelon Kush and 19% in Zkittlez; however, Watermelon Zkittlez strain's THC level is a hefty 25%. It has the potency to knock both parent strains off their feet and delivers a chart-topping high. The lowest THC level was around 15%, but this is not the standard.