Optimizing Vegetative Growth

Whether you germinated seeds to grow healthy seedlings or propagated clones from a mother plant, optimizing your plants' vegetative growth cycle is important to the final outcome at harvest, both for quality and yield.


As is always the case when growing cannabis indoors, control of environment is critical to optimizing vegetative growth. The controlled parameters are air temperature, humidity, and light. Temperature should be maintained between 60 and 80 degrees Fahrenheit, relative humidity at 60 percent, and light should be high intensity fluorescent (T5 HO) maintained within 6 inches of the tops of growing plants.

There are no excuses or workarounds for poor environment. When attempting to grow cannabis indoors, success depends upon maintaining the proper environment. While our favorite plant may be able to withstand many abuses and survive in many conditions, our goal is to help our plants thrive, not merely survive. Creating a suitable environment requires some basic skills, common sense, and almost certainly requires some spending. Spending money on good environmental control is never wasted - don’t cut corners. Take care of your environment first. Do not add plants to a garden that is has not been properly set up and tested for temperature and humidity over a period of a few days and nights. Don’t even think of asking Uncle Pete for cuts or plants unless you have a garden in which they can thrive. We don’t have an endless supply and we expect our members to be successful!


While there are many ways to grow cannabis, Uncle Pete's methods are tried and true - proven over many years. He prefers 24 hours of light for vegetative growth for its simplicity and growth rate. There are many treatises which argue that the plant must rest and sleep…don't believe it. While the indoor gardener can manipulate plant growth extensively using photoperiod, even confusing it into maturing early, these techniques are nothing more than fun in Uncle Pete’s opinion - there is always a trade off in growth rate or yield at harvest. After all is said and done, 24 hours of light for vegetative growth is the best use of time and electricity for the indoor gardener.

For early vegetative growth of cannabis plants, large, high-intensity fluorescent lights such as 4-foot, 8-lamp high-output T5s are generally the best choice. These T5 HO fixtures spread an even light for vigorous plant growth without adding the heat of larger high-intensity discharge (HID) lamps. Use lamps with a color temperature in the 5000-6400k range (cool white or daylight).

Later vegetative growth (if needed for very large plants) is best under a 1000 watt double-ended (DE) HID fixture such as those produced by