by Nebula Haze
Table of Contents
Strain Characteristics (Height & Overall Growth Speed)
Time to Harvest (Length of Flowering Stage)
Growing Multiple Strains Together
Many indoor cannabis growers want to grow multiple strains together so that they have a greater variety of bud to choose from after harvest. Additionally, maximizing your grow space by growing many plants can increase overall marijuana yields!
- Greater variety of strains after harvest
- Growing many plants can increase yields
- May take more time and effort to care for plants with differing needs
- More likely to run into space or height issues if not paying attention
- Plants may be ready to harvest at different times
Good planning goes a long way!
You will get more variety if you grow multiple strains at once, but sometimes it can get a little crowded!
Strain Characteristics (Height & Overall Growth Speed) – Each strain and individual plant can grow differently from each other, even in the exact same growing conditions. They tend to grow to different heights, with some growing tall and thin with others growing short and bushy. One of the most important strain characteristics for indoor growers is the estimated Flowering Stretch, or how much the plant will "stretch" after the switch to the flowering stage.
Time to Harvest (Length of Flowering Stage) – How long it takes buds to mature before they're ready to be harvested.
Giving Plants Equal Light – Although it's impossible to give every plant the exact same amount of light, there are important strategies to maximize the light received by your main bud sites.
Reaching All the Plants – If you've got a lot of plants in rows, it can be difficult to reach the plants in the back. This can be tough when it comes to training, diagnosing sick plants, and even basic activities like watering and collecting runoff.
Size of Plants / Over Crowding – If you're not careful in the vegetative stage, it's easy to overload a grow space if you're growing a lot of plants at once. When your grow space gets extremely overcrowded, you increase the risk of white powdery mold, bud rot, certain types of bugs and overall slow growth on plants that get "crowded out." Luckily, a little planning will make things go much smoother!
These three plants were grown together in the same environment without any training from germination. Even though they were treated exactly the same, they are vastly different heights!
Growing multiple strains can be done in an orderly way with some planning!
Each strain has different tendencies when it comes to overall growth speed and estimated height. Some strains grow tall and stretchy, while other strains grow short and bushy. Additionally, different individual plants of the same strain may grow differently from each other, especially if they come from seeds as opposed to clones (which are exact copies of each other).
Each cannabis strain has unique tendencies and characteristics. For example, these outdoor cannabis plants of different strains all turned different colors right before harvest!
Main Ways That Strains Differ From Each Other
Bud Quality – Color, density, flavor, smell, "sparkle" and more are all determined mostly by genetics. Learn about improving bud quality.
Height & Growth Speed – Overall "stretchiness" compared to naturally staying short and squat. Some strains tend to just overall grow taller or faster than others.
Estimated Flowering Stretch – This goes along with height, but basically once plants are switched to a 12/12 light schedule to initiate the flowering stage, they dramatically increase their height before being ready to harvest. Some plants stretch a little, some double in height, and some plants may even triple in height after the switch to 12/12! It's important to have an idea of what to expect so you can plan for it!
So before you get started, if you plant on growing many different strains together in the same space, you will be well served by choosing strains that somewhat match each other!
Here's a picture story of what happens when you try to grow two poorly matched strains together.
One of the biggest challenges with growing several different strains of cannabis together is pace of growth. Different strains often grow at different rates in both the vegetative stage and especially during the flowering stretch (the quick growth that happens immediately after the switch to the flowering stage).
Let's see what happens when you grow an Indica plant next to a Sativa plant in the same setup with the same nutrients!
Left seedling is an Indica strain. Right is a Sativa. You can see the Sativa is already growing just a touch "stretchier" and less bushy than the Indica, but the difference is growth speeds will become a lot more apparent soon.
Even though both are in the same conditions and have been trained the same way, they look decidedly different as they continue growing. The Indica plant tends to grow very symmetrical and bushy, while the Sativa grows more tall and wild.
A few weeks later, after some plant training and right before the switch to the flowering stage
Nearly a month after the switch to 12/12, the flowering stretch has mostly stopped. The Indica plant on the left has stretched far less than the lanky Sativa on the right. The plants may get a little taller, but by 4-6 weeks into the flowering stage they'll be focused almost completely on making buds.
The grower raised the shorter plant so it could be closer to the light. As is common with Indica plants, it was more sensitive to heat and light, and couldn't be kept as close to the HPS as the Sativa.
The grower harvested both plants at the same time even though they matured at somewhat different rates. The Indica plant was taken down a little late according to its trichomes, and the Sativa plant was taken down a little early. Which plant do you think ended up getting better yields?
In this case, the Sativa plant ended up getting almost 1.5x the yields of the smaller plant!
Indica Plant at Harvest (6.6 ounces)
Sativa Plant at Harvest (9.3 ounces)
The strain makes an insane difference when it comes to how your plants grow and how much they yield! These plants were grown in the exact same setup, with the same nutrients, grow light, etc, and came out completely differently from each other!
Although you can get around differences like this between strains, it helps greatly to research your strains so you know what to expect in the grow room if you plan on growing multiple strains together!
In the Tale of Two Strains, we saw how a grower harvested two plants at the same time, but had to harvest one plant a little early and the other plant a little late. Fortunately, there is a time window of a few weeks where buds can be harvested, but bud effects do change over time!
When growing many different cannabis strains at once in the same grow space, some plants will likely be ready to harvest sooner than others.
On average, most cannabis strains need about 9-12 weeks in the flowering stage after the lights have been switched to a 12/12 light schedule before they're ready to harvest, though some strains are ready in as little as 7 weeks, and some as long as 16 weeks or more.
The biggest factor when it comes to time-to-harvest is strain. If you give a bunch of different plants the exact same growing environment, the genetics are going to mostly dictate how long buds take to mature.
Luckily, when shopping for seeds, nearly all strain breeders usually give you an estimated flowering time for each strain!
Read more: Why are buds taking forever to mature? (and how to speed the process up)
So if you plan on growing many plants together, consider that a strain which needs an 8 week flowering stage is going to be ready to harvest a lot sooner than a strain with a 16 week flowering stage.
Tip: Breeders often count from the beginning of the harvest window. It's a good idea to add ~2 weeks to most breeder estimates to achieve peak ripeness, though inspecting the buds is the most accurate way to choose harvest time.
There's nothing wrong with harvesting your plants one at a time as they become mature, but the length of the flowering stage is something to keep in mind if you prefer one big harvest over a bunch of smaller ones.
Even though they grew to different heights, these brightly colored auto-flowering plants were all ready to harvest around the same time because the grower matched the strain's estimated harvest times with each other.
You'll rarely be able to give all plants the exact same amount of light coverage. If you have a lot of different plants, some plants are going to be bigger or closer to the light despite your best efforts. Just try your best and focus on the plants and buds you are most interested in!
Most of the time, the buds that get the most dense, long and thick are located at the top of your plant near the grow lights. So you want to get as many main buds as possible in that position before your plants start flowering.
Notice how the buds get smaller as they get lower on the plant and further from the grow light
Although it's impossible to give every plant the exact same amount of light, there are important strategies to maximize the light received by your main bud sites:
Bend over any colas that are getting taller than the others
When any of your main colas gets taller than the others, bend it down and away from the base of the plant, optimally towards a spot under the light that doesn’t have any other buds.
This works best if you're checking on your plants regularly so you can catch any problem stem(s) early before they get out of control and become difficult to bend over. If you pay attention you can also train unruly stems to fill "holes" in the canopy that are lacking a cola.
If some of the plants or colas are getting taller than the others
Bend all the tallest stems over so they're the same height as the other colas and plants, and secure in place. Just following that principle as your plants grow will give the shape you want!
You can't fight a plant's true nature, but you can use plant training to work with it!
Fill In Empty Spots in the Canopy
Whether growing one plant or many, you always want to fill up any "empty" spots in the canopy by bending one of the tallest colas down and into the empty spot. That not only flattens your plant but fills in your canopy with more main bud sites. This arrow points to an example of an empty spot.
Support Your Plants
There are many ways you can support your plants, including stakes, tomato cages, bendable wire, plant ties, etc.
If you've got a lot of plants in an enclosed space, you want the flexibility to be able to train your plants to grow into any shape you want. By installing supports when your plants are still young, it gives you a better ability to train your plants because you have more things you can secure your plants with/to.
Additionally, plant supports help big plants from falling over as buds get heavy!
These pictures by commercial grower Davie Jones help illustrate how stakes can be used to support the plants and keep the canopy relatively flat and even. He started with several cannabis plants of different strains.
Each plant is given its own stake to hold the plant up as it grows. These also provide a support structure to tie down unruly stems on plants that are getting taller than the others. Many growers also like tomato cages because they give a grower more places to anchor stems from. Initially there's room for rows to better reach the plants, but soon they'll get too big for that.
The plants are allowed to gain some size and get placed in their final destination. Some plants will always be smaller than the others, like the plant this arrow is pointing to. Unfortunately you'll never get a "perfect" canopy, and that's okay! Just try your best with the plants you have!
Bend over the extra tall stems, give the shorter plants a good place with direct light, and otherwise let the plants do their thing throughout the flowering stage when you have this many crammed into such a small space. There's always going to be unruly stems, especially in the back where you can't reach!
The grower was rewarded with more than 15 lbs (240 ounces) of premium dried bud from this grow! Huge harvests can be one of the benefits of growing tons of plants, but keeping all your plants in a relatively flat shape like this is what maximizes indoor yields!
One of the hardest aspects of growing many different plants in a grow space is it can be difficult to reach all the plants, especially the ones in the back. As you saw in the above example, it's common to see tall, unruly stems in the back of a grow space with a lot of plants!
Whether it's plant training, watering, or collecting runoff water, it can be hard to tend to the basic needs of a plant when you can't reach it! But there are a few tricks!
Ideas to Help Care for Plants in the Back
More Than One Entry to Grow Space – Set up your grow space so you can access the garden from more than one side (for example a grow tent or room with more than one access door)
Get Help Watering Plants in the Back – A common tool for this problem is a big watering can to help you reach plants in the back. Or better yet, set up an automatic watering system that uses drip lines to water each plant individually with tubing. Once an automatic watering system is setup, you won't have to worry about getting water to the plants in the back!
Force Runoff Water to Pool to the Front – Put all plants on a slightly inclined tray. This causes all the water runoff coming out of the bottom of your pots to come to the front of the tray so you can suck it up with a Wet Vac.
Try Your Best! When it comes to plant training the only thing to do is try your best 🙂
Not sure how to remove runoff water after watering your marijuana? Wet vacuums can be helpful! I use a Bucket Head attachment which can be turned into a wet vac by hooking it up to any standard 5-gallon bucket. You can buy one online but it's $10-15 cheaper if you get one in person at a Home Depot (it's made by Home Depot)!
A downside to the Bucket Head is it's a little loud, just like most wet vacs. Luckily you only need to use it for a few minutes after watering your plants!
As you just saw, it doesn't take long to completely fill a whole room!
When you have a lot of plants in a very limited space – like a grow tent with only a few feet in each direction – it can be easy to overgrow your tent without even noticing it!
It might take 1 or 2 plants several weeks to fill your grow space, but if you're growing 10 plants at a time they'll fill that space much sooner!
When growing many different marijuana plants, they will fill up the whole grow space quickly than just one or two plants
Just 2 weeks later, the whole 4'x4' (1.2m x 1.2m) space is quickly getting filled by plants (even though each individual plant is still relatively small)
The grower had to toss 4 plants that were males or hermies, but even with just 7 plants left, the entire bottom of the tent is soon covered from wall to wall. A few days after this picture, the grower put these plants in bigger containers and switched to a 12/12 light schedule to initiate the flowering stage.
It's important to stay aware of the fact that each plants can potentially double in size after the switch to the flowering stage, and certain strains may even triple in size! You need to leave enough room to care for your plants, as well as prevent them from growing into the ceiling!
This is often easier said than done. Sometimes you may realize too late that your space is overcrowded, or plants may stretch more than expected. If that happens, just try to bend down any stems that are growing into the light and otherwise try to hold out until harvest.
Most plants about doubled in size after the switch to 12/12, but this one in the corner tripled! It's a good thing the grow tent is 6.5 feet (2m) tall!
It's a jungle in there! With so many plants, it's a sea of developing buds!
Although it can be a lot of work, growing multiple strains at the same time gives you a bigger variety of buds after harvest, and if you take care of your plants you will also get great yields!
Hopefully by now you have at least a rough idea about whether growing multiples cannabis strains together would be a good fit for you, and if so, the best way to go about it! Growing multiple strains can offer great rewards if you're able to put the effort into it!
Who doesn't love variety?
Next, learn how to improve…