Perpetual by definition means 1. Never-ending, 2. Occurring repeatedly; so frequent as to seem endless and uninterrupted. Those are words we would all gladly associate with our harvests! Once you get your grow room thriving and producing acceptable dankness having a more frequent, continuous cycle of harvesting is just a few steps away.
Normally a basic HID light set up has a ballast plugged into a hood or reflector, that powers one light. You will then need two separate bulbs each containing a different spectrum of light, one for vegetative growth and one for blooming/flowering growth. You switch these bulbs out when you cut the light hours back to the 12/12 cycle for bloom.
Starting a perpetual harvest cycle will almost always require an investment in more equipment because more plants you have the more space, more light and more everything you will need. You will need to separate the vegetative and blooming growing areas with a partition, one that is sealed to prevent light leaks which can be detrimental to the plants on either side of the wall. Use light proof materials such as panda film, wood or foam board to build the partitions. This is also a great opportunity to use a grow tent. But if you don’t have any more space to work with then you will need to divide up the space you have and grow fewer plants per cycle. I know that doesn’t sound ideal but when you can triple or even quadruple the amount of harvests you can do in a year it will work out mathematically in your favor.
Selecting a new light for your separate vegetative area is also an opportunity for you to save some money on electricity, simply by leaving your powerful HID lights for the bloom/flowering area and purchasing a T5 fixture for the vegetative area. While these T5 bulbs usually don’t come packing the lumen output of HID’s they also don’t use a lot of energy to run and work great for veg when your plants don’t need that intense light to thrive. They are also nice because they don’t put off a lot of heat, which means you can get them really close to the plant canopy without the risk of burning the tops. While these T5 units are one option you can use any type of light you choose just make sure the bulb is a vegetative spectrum bulb. This area will be used for cloning and vegetative growth and then plants will be transferred to the blooming area when it is time to flower them. Make sure your flowering area has a bloom spectrum bulb and its own separate timer.
Growing plants in individual pots allows for them to be moved freely from room to room making the perpetual harvest process easier and more flexible with shorter intervals. Seeing as they are not connected to each other or using a shared reservoir it allows them to be fed different nutrients to coincide with the cycle they are in. Whether it is in soil/dirt or soilless medium or individual DWC (Deep Water Culture) buckets moving your plants from one area to another is easy, but what if you run a hydroponic system with a shared reservoir? This will require you to add more hydro systems grouping them by the nutrients and bulb they need. Using the same light fixture set-up in each area you can simply switch the bulbs out or grow using removable medium (such as rockwool blocks or containers filled with grow rocks) and move the plants to the room with the reservoir and light they require. While doing it this way means less staggering of the groups, you can still double your harvests. If your hydro system has plants that are all in one tray/container where the plants grow to intertwine with each other method rendering them stationary, then switching the bulbs out is the way to go.
Another benefit to growing in individual pots is that you can have more a staggered harvest cycle, allowing the possibility of harvesting once a month or every two weeks. A sample schedule is to have your room set up in four different stages, such as; 0-2 weeks, 2-4 weeks, 4-6 weeks and 6-8 weeks. Depending on the length of time your plants need, from start to finish, it will change these stage estimates a bit, but you get the idea. This also means that you need to feed all the plants in different parts of the cycle different nutrients and additives. It’s easy to get confused if you don’t write yourself a personalized schedule and post it on the wall in each area.
The perpetual harvesting method employs the old adage; the more you want to put into it, the more you will get out of it. I have seen successful grows that are perpetually harvesting as frequently as every week. Now that’s production!
Another thing that can take your perpetual harvesting to a whole other level is the auto-flower