No no......no need to measure it. About 20" is close enough. I just look at some plants that to me they look REALLY TALL where most of my plants are pretty short. BUT, that one I've told you about a few times will be the first plant I've not "rushed" into flowering. I bought those 5 gallon fabric pots and have been topping and LSTing it for a month now. I will be harvesting 2-3 plants in about 3 weeks and she will replace those. When I severely split the main stalk seems to be forming a nice callous and is healing up. At your suggestion I brushed on some Clonex Solution which I believe helped it to heal itself up.