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Perpetual Harvest — the Ultimate Guide

Created by
JoshuaHolt JoshuaHolt
Added 14 April 2022

An endless supply of fresh cannabis buds — sounds too good to be true, right? But fortunately, it is true. 

You can get an endless supply with perpetual harvest, which is a system that allows you to harvest cannabis every eight weeks. The idea is simple (though executing it may require some labor and time), but it is the best way to get a steady supply of fresh buds, so you never run out.

In this article, learn everything you need to know about perpetually harvesting cannabis.

About Perpetual Harvest

perpetual harvest

Perpetual harvest, also known as symbiotic rotation, is a system where you use multiple grow tents or rooms to ensure plants are growing in both the vegetative and flowering phases simultaneously. 

For instance, you grow a batch of plants in their vegetative stage in one grow tent, while another grow tent can house flowering plants. Once you harvest the buds from the flowering plants, you can move the plants from the vegetative grow tent into the flowering one. Next, you can replace the vegetative plants with rooted clones. And the cycle will continue.

It sounds like a lot of work, doesn't it? It's not. And the benefits far outweigh the time and effort you put into it. Perpetual harvest has two significant benefits, as mentioned below.

  • Endless Supply of Cannabis

Running out of buds is not fun — who wants to wait a few months before getting fresh buds? So, with perpetual harvest, you can ensure you get buds every eight weeks. You will never run out of cannabis!

  • You are Always Prepared

There are two ways perpetual harvest can help you recover from problems with your cultivation.

First, if you make a mistake and compromise your harvest, you don't have to wait too long for another crop. Instead, you will have another set of plants waiting to be flowered in the vegetative room.

Second, you will not run out of your preferred plant if your seed or clone supplier shuts down. 

Setting Up a Perpetual Harvest System

Your perpetual harvest setup can be as big or small as possible, but you must be careful in designing the system. A wrong system can compromise both your flowering and vegetative plants. 

Things You need

When setting up a perpetual harvest system, some things are necessary for the setup, such as the following:

  • An Extra Grow Tent or Room or Multi-chamber Grow Tent

extra grow tent

Whether you use grow tents or rooms, you need two of them so you can grow plants in both vegetative and flowering stages separately. 

This is because plants in different stages of growth require different amounts of light and nutrients, which is impossible to have if they are placed in the same grow area.

You can even split the growing area into two if you are short on space. We'll get more into this later.

  • An Extra Set of Grow Lights

extra grow light

The next thing you need is extra light panels for both growing areas. You can use your primary grow lights in the flowering room and weaker lights in the vegetative room since young plants don't require as much light as the flowering plants.

  • An Extra Carbon filter

extra carbon filter

Now that you're growing double the number of plants in two grow tents, you will need an extra carbon filter so the odor isn't too noticeable. 

Steps to Set Up Your Perpetual Harvest

Follow these steps to set up your perpetual harvest system using two growing areas.

  • Step 1. Secure Your Garden

secure your garden

You are growing two batches of cannabis, so ensure your garden is secure from the outside world. Check for light leaks in your grow areas or any way for the odor to leak and annoy your neighbor.

  • Step 2: Set Up Your Grow Areas

set up the grow area

Your grow area's setup depends on your preference and available space and resources. 

But remember, the goal is to have two copies of your standard grow room or tent, where one is set up for vegetative plants and the other for flowering plants. 

However, your vegetative area can be smaller if you prefer. You will also use the same space for clones, so plan appropriately. 

Also, have both the areas, especially the flowering area, ready to combat odors. Air scrubbers like carbon filters work the best to reduce strong cannabis odor.

Most importantly, ensure your flowering area is entirely lightproof. Light leaks during this stage can stress the plant and push them into re-vegging or turn them into hermaphrodites

Make sure your grow areas are close by and have easy access to each other, so you can move the plants quickly when the time comes. Ensure that both the growing systems allow the plants to be moved around easily with minimal disruption to the plant.

  • Step 3: Start Growing the Plants

start growing the plants

You can introduce your young plants to the vegetative grow room at this point. So, whether you use clones or seeds, we recommend rooting them in your regular germinating area and moving them to the vegetative area once they are ready.

We recommend using numerous small plants over a few big plants because moving them around is easier.

  • Step 4: Move the Plants to Flowering Tent and Vegetate the Next Batch

Vegetate the next batch

Once your vegetative plants reach the desired height, it's time to move them to the flowering area. But, again, move them carefully to avoid shocking or stressing your plants.

After moving the plants, start another batch of rooted clones or seedlings in the vegetative room and let them grow. This is called resetting the perpetual cycle, and you must do this every time you move your vegetative plants to the flowering area.

In the flowering area, maintain a 12/12 light schedule to switch them into the flowering stage. They will start growing and filling up the entire room within a few days.

You can harvest the plants after eight weeks (or more, depending on the strain). Post-harvest, move the second batch of vegetative plants to the flowering area and continue the cycle.

Sample Schedule for Photoperiod Strains

clones for perpetual harvest

If all this sounds confusing, here's a simple schedule you can follow, assuming you're using clones. 

  • Begin by taking a few cuttings from your preferred mother plant. Next, wait for them to develop roots and establish themselves for 1-2 weeks. 
  • Select good clones that are rooted well and transfer them to the vegetative tent. 
  • Start the 18/6 cycle and let them grow for at least two weeks. Once the clones have several nodes, you can start training them. You can use Topping, FIMming, LST, or other techniques you prefer. 
  • Let the plants spend another four weeks in their vegetative stage, which means it's about six weeks in total in the vegetative stage. During the second week, start preparing new clones so they can replace the first set of plants. 
  • Transfer the first set to the flowering tent and let them grow for about 4-5 weeks in the 12/12 cycle. Transfer the second set of clones into the vegetative tent. After three weeks, you can start preparing another batch of fresh clones. 
  • Now, once the plants are ready to be harvested in the second tent after spending 4-5 weeks, as mentioned above, you'll see that the plants in the first tent are ready to be moved to the flowering tent. If you have prepared your clones already, you can transfer them to the vegetative tent. 

This schedule will allow you to harvest at least eight times every year. Of course, the timelines will vary depending on the strain. Plus, there will be changes if you decide to grow from seed. However, you can use it as a base and make some alterations according to the strain you wish to grow. 

You can also add chambers in your grow tent or buy a multi-chambered grow tent if you don't want the hassle of transferring the plants from one grow tent to another. But, you will have to reduce the plants you originally wanted to grow. 

Clones or Seeds?

clones or seeds

You can use both clones or seeds for your perpetual harvest. It depends on your personal preference and the timing. You may have to practice before getting it right, but it becomes easy once you understand how the plant grows. 

Of course, you'll need to do some planning for clones because they will need to be taken from the mother plant. You can grow the mother plant from seeds or purchase one from your local nurseries. Note that the mother plant will need to perpetually be in its vegetative stage, which means that it will have to be in the 18/6 cycle. This is important, so the plant doesn't start flowering. 

One reason to choose clones is that they tend to be their mother's replica. Therefore, they may match their mother's vigor, yield, taste, etc. However, remember that there will be a decline in their performance every time you take some cuttings. This is because genetics tend to get weak after every season. 

On the other hand, growing from seeds may be better if you don't have a room dedicated to the mother plant. However, this will require some planning as you need to calculate the amount of time the plant spends in its seedling stage.

One advantage of growing from seed is that the plant yields more than clones. Plants growing from seeds will produce taproots functioning as anchors. In addition, they provide more support to the plant with better abilities to absorb nutrients. Growing from seed will help the plant fight against diseases and pests better. 

However, clones do not have taproots. This doesn't mean they are weak, but you will need to choose a different mother plant after a few sessions to prevent any decline in performance. Plus, it's free to get clones, whereas you will have to spend a small fortune to get seeds frequently. Seeds also take longer to finish their seedling stage, whereas a clone may be rooted and ready in just a week or ten days if you do everything right. 

Whether you choose clones or seeds, keep in mind that the timing is essential for perpetual harvests. You will be able to get better with practice. 

Perfecting the Rotation Timing

Perhaps the most challenging part of the perpetual harvest setup is the timing. It can be confusing, but here are some tips to make it easier.

To get the right timing, you must first understand the growth pattern of your strain or choose the right strain for this setup. Strain genetics dictate the flowering cycles, so this step is crucial.

Ideally, it would help to choose a strain with a short flowering stage of around eight weeks to harvest your crop more often. 

As for the strain's vegetative period, it can be a bit flexible. Eight weeks make the technique more manageable, but you can work with a couple of weeks, give or take. Also, the time for vegetation depends on many environmental factors, too. So you can fine-tune your setup accordingly.

Also, plants growing in deep water culture or bubbleponics can flower a lot quicker — within four weeks — which can be an issue. And on the other hand, some strains can take up to 12 weeks to flower properly. 

So, if your strain flowers early, you can just cut it down. 

And if it needs a more extended flowering period, you can switch to a 12/12 light cycle in the veg room for four weeks, letting them flower, and then move them into the flowering area for eight weeks to finish flowering. Or you can wait and harvest every 12 weeks instead of 8. 

But don't worry if your harvest is off by a couple of weeks — every strain and growing environment is different, so your plant may grow faster or slower than you anticipated. And that's normal.

Best Strains for Perpetual Harvest

All cannabis plants are different, and some strains take longer than others to be ready for harvest. This can throw off your schedule. So, it's best to choose a strain that can be harvested around the eighth week of the flowering period. 

You can choose from three different strains: sativa, indica, and ruderalis (autoflowering). We recommend choosing Indica strains for perpetual harvest. 

Sativa-dominant strains tend to grow taller, and hence, they take longer to reach maturity. Typically, sativa strains take 9 to 16+ weeks to be ready for harvest. Also, rotating them can be pretty labor-intensive, thanks to their sprawling stature.

On the other hand, indica strains grow shorter and have a shorter flowering phase. So, indica-dominant strains are more suited to grow in a timed setup while being easy to rotate between the grow rooms.

Before you choose your specific strain, we recommend reading through the seed bank's detailed descriptions to find the height and flowering time of the strain. A reputable seed bank will provide this information on the product page itself.

What About Autoflowering Strains?

Autoflowering strains are best if you don't want the hassle of managing two separate grow rooms or using multi-chambered grow tents. 

Not everyone can dedicate two grow tents. You may not have the space, and it's not cheap to buy all the equipment either. 

These strains don't rely on light cycles to start flowering, so you can grow plants at different growth stages in the same grow area at the same time. 

Just ensure you keep the light at the proper distance from the plants since some close to maturity will be taller than young plants. You can even use training methods to keep the mature plants short or raise smaller plants using bricks or buckets. 

Autoflowering Strains for Perpetual Harvest

It's extremely easy to get a perpetual harvest with autoflowering strains. A few years ago, growers would hesitate to grow autoflowers due to limited yields, but it's no longer the same, thanks to how autoflowers have evolved.

Although autoflowers may not yield as much as photoperiod strains, they are excellent if you're looking for perpetual harvests.

What makes autoflowers one of the best candidates for perpetual harvests is that they save time and money.

Autoflowers are quick to grow. Unlike photoperiod strains, they don't depend on light to start flowering. Instead, they rely on their age to flower. For example, photoperiod strains will need at least eight months in the vegetative period and another 6-8 weeks in the flowering period, depending on the strain. You can plan things around their lifecycle to make sure you get a perpetual harvest.

On the other hand, autoflowers may need about 4-5 weeks in the vegetative stage and another five weeks in the flowering stage. Of course, it may vary from one strain to another. However, most autoflowers finish their lifecycle within 10-12 weeks, making it incredibly easy to get perpetual harvests.

And, the best part? You can do it all in one tent. A single tent will suffice since autoflowers will grow perfectly well in the 18/6 cycle in both its vegetative and flowering cycles. This will not be possible with photoperiod strains. 

Why? Imagine you plant a few seedlings, and they grow for a few weeks in the 18/6 cycle. They will begin to flower only after they switch to the 12/12 cycle. Thus, you will have to wait for weeks together for them to finish their cycle and harvest them. Suppose you introduce new seedlings in the same tent with older plants in the 12/12 cycle. In that case, they will all switch to the flowering cycle immediately, and you'll experience a significant /reduction in yields, which beats the purpose of perpetual harvests in the first place. 

Now, since autoflowers aren't bothered by the light cycle, there won't be any changes in the plant. The only thing is that you may not have enough space to introduce new plants. Plus, they may not produce as much as photoperiod strains. 

Note that it's essential to train the autos, or you'll end up with plants with varying heights. One easy way to control the height is to use the Sea of Green technique. Or, you can employ the ScrOG technique. 

Both techniques are beneficial to maintain an equal canopy. However, one big difference is that while SOG requires many plants with minimal time in the vegetative stage, ScrOG will need fewer plants with more time in the vegetative or growing stage. 

Schedule for perpetual harvests with autoflowers

You don't really need a schedule to grow autoflowers for perpetual harvest because it's as simple as popping a few seeds and waiting for them to do their thing. Also, you don't need to make special arrangements to get multiple harvests because they grow in one single tent. 

However, one con of using autoflowers is that you can't get clones. Since the plants will flower automatically, depending on their age, you can't use clones. Even if you get a few cuttings and root them, they will start flowering after a while, and you'll end up with minimal yield. 

Sample Schedule for Autoflowering Strains

  • Plant a few seeds and wait for them to germinate. 
  • Once the seedlings emerge, wait for them to finish their seedling stage and grow till the end of their vegetative or growing stage. This may take about 4-5 weeks or even six weeks, depending on the strain. 
  • Once you see a few pistils appearing on the plants indicating they have entered the flowering stage, plant another set of seeds. You don't need another grow tent for the germination process. A small area in your current tent will work; however, ensure the seeds aren't getting too much light. 
  • After the first set of plants has reached the harvest stage, your second set of seeds must be in their pre-flowering stages. Plant another batch of seeds and repeat the cycle. 

Another method is to wait for the first set of plants to enter the last week of flowering. Then, you can plant some seeds and transfer the seedlings to the grow tent. Perpetual harvests with autoflowers will be easy if you learn the art of transplanting them without hurting the roots. This way, you can germinate the seeds in small cups and transfer them to bigger pots. 

Summary: Perpetual Harvest — the Ultimate Guide

Despite the initial investment in time, labor, and extra equipment, a perpetual harvest setup can be rewarding if you want an endless supply of buds. Plus, if you're going to grow commercially, you can never go wrong with this setup, as you can sell your buds without risking inventory shortage.

Just follow the tips mentioned above, and soon enough, you will have your supply of buds that never runs out!

 






Comments

NobodysBuds
NobodysBuds

As someone that used to run on a perpetual cycle, think twice about it... the opportunity for waste increases. (time, effort, resourecs, etc)

anytime you have to delay, you are using way more electricity and resources during that delay keeping soe vege plants waiting and finishing up a bloom cycle... vege time that would have never happened otherwise..

any hiccup and it's a greater cost than a normal grow cycle.

If you can, consolidating and doing full runs is definitely more efficient use of resources. there are still reasons where the waste is acceptable relative to other needs - use imagination.

if you can do a bigger room and fewer runs per year, definitely do that. The economies of scale are worth it... avoid any context where previous grow impacts the next grow and the extra costs that come with that (our tme and effort being the biggest concern).

a perpetual grow in theory shuld be a similar productivity ( = yield per increment of time, not just how big 1 harvest is without considering time to produce). But, in reality it will always be less. Far more opportunity for issues to crop up. You will produce more per year doing things all at once or merely overlapping in a conservative and safe way with some young vege plants.. can still shave off 2-6 weeks off a 2nd+ consecutive grow depending on size of a 2nd area used. young plants don't need much.

Plus, one catastrophe and you are out of weed for a full cycle (3-4months, retroactively). if you've been persisting on smaller batches, that'll run out before you get to 'next' harvest. as we are seeing the negatives to JIT (just in time inventory methods) in our global supply chain, the same type of problems will occur in this setup too with minor blips or major ones. it's great on paper, but falls short of epectations.