Marijuana plants spend a lot less time in grow phase than they do in bloom phase, and marijuana bloom phase often reminds us of the Tom Petty song that says “the waiting is the hardest part.”

Marijuana growers try to hurry bloom phase up using various methods and materials, but can you speed up bloom phase while still having your marijuana plants produce their heaviest, most potent harvest faster than it normally would?

Let’s take a look at the common bloom phase acceleration strategies and see if any of them really work.

Marijuana Genetics & Bloom Phase Duration

The obvious and easiest way to have a fast bloom phase is to grow marijuana strains that have a fast bloom phase. These strains have a heavy Indica presence. Photoperiod marijuana strains with significant Sativa influence rarely have bloom phase lasting less than nine weeks.

Autoflowering cannabis is advertised as finishing faster than photoperiod strains because the plants start flowering on their own without grow light cycle manipulation within 2-4 weeks of germination. Seed companies often claim that the total autoflowering crop time from germination to harvest is 8-10 weeks.

However, we’ve grown dozens of autoflowering strains and none of them have ever finished that fast. Recently, we’ve noticed that some autoflowering seed companies are being more honest about crop cycle duration.

In our experience, autoflowering strains producing harvest weight and potency comparable to photoperiod strains of the same type (autoflowering Haze versus photoperiod Haze, for example), aren’t ready much earlier than photoperiod strains when you compare overall crop cycle duration.

The generic expectations for photoperiod strains is 3-5 weeks in grow phase, and then 8-12 weeks in bloom phase. Autoflowering strains spend 2-4 weeks in grow phase and about two months in bloom phase. You may save a few days using autoflowering strains, but you often have lower yields and potency, and you can’t easily clone or breed with autoflowering strains.

Bud Hardeners, Bulking Formulas & Bloom Phase Accelerators

General Hydroponics makes a product called Bush Load that allegedly accelerates bud formation and makes “harder” buds. Bush Load contains Paclobutrazol, a controversial plant growth regulator banned in most legalized marijuana state’s regulations because scientists suspect it’s a carcinogen and damages the liver.

Other companies also make products that allegedly accelerate bud production and increase bud density. These products include B-Nine WSG, Ethephon 2 SL, Rock Resinator, Bushmaster, Hulk PGR, Phosphoload, Gravity, and G-10.

Some but not all these products contain Paclobutrazol and/or daminozide (Alar) although neither of these substances are considered safe for use on marijuana plants.

Advanced Nutrients makes Bud Ignitor, claiming the product creates more and earlier budding sites and faster bud formation.

Some of these products are advertised as being “vertical growth limiters,” which means they inhibit upward growth, making plants shorter than they’d normally be. Problem is, when we tested those products, we noticed that they reduced harvest weight and resin gland formation.

We’ve used all these expensive products in side-by-side testing and seen no worthwhile effects. In fact, some of these expensive products severely damaged our plants and buds and/or they contain plant growth regulators and other chemicals said to harm human health.

The California Department of Food and Agriculture, along with other regulatory agencies, have banned the use of these types of products and ordered grow shops to stop selling them. But many products sold to marijuana growers as bud hardeners, bud bulkers, resin boosters, height limiters, and bloom phase accelerants are sold clandestinely, black label, behind the counter.

I’ve shopped at hydro stores in some states where they keep these banned products hidden away and only sell them to “trusted” customers.

Grow Light Manipulation

You trigger photoperiod cannabis to begin and stay in bloom phase by giving it 12 hours of total, uninterrupted darkness and 12 hours of light during every 24 hour period.

In some photoperiod strains heavy with Sativa genetics, we’ve had to give 12.5-13.5 hours of darkness per day initially to push the plants out of grow phase and into bloom phase. In rare cases, we’ve had to continue that regimen to keep the plants blooming properly.

In the vast majority of cases, however, giving less than 12 hours of light every 24 hours doesn’t accelerate the onset or rate of bloom phase floral maturation. It also deprives plants of the light energy they need for maximal bud formation.

Some growers experiment with interrupting the dark cycle, making plants endure 1-2 days of total darkness, far infrared light, dialing in different light wavelength recipes and other tricks they believe are clever bloom phase hacks that accelerate bloom phase finishing.

We’ve tried them all, and looked at cannabis grow lights research data, and find no evidence these methods make bloom phase shorter or more productive. Instead, these methods often cause needless stress for marijuana plants, leading to hermaphroditism, a longer bloom phase, and other problems.

Hydroponic Nutrients & Supplements

Many hydroponics and so-called organic and nutrients manufacturers advertise products they claim as bloom phase accelerators. The claims include the assertion that a product causes budding sites to develop faster at the start of bloom phase, hastens floral maturation, and causes extra resin production.

Most of these products only contain potassium and phosphorus. Some of them contain covert chemical or natural plant growth regulators.

In extensive testing using clones, we’ve never seen a measurable difference in bloom phase duration or resin percentages caused by individual products or hydroponics feed programs advertised as accelerating marijuana bloom phase.

Torturing Marijuana Plants

Some growers torture their marijuana plants, believing plants will react by hurrying up and finishing bloom phase. Torture tactics include creating drought conditions, light deprivation, starving plants of nutrients, and other cruelties.

The cannabis torture program has the same mistaken ideology as marijuana flushing. The idea that you get your heaviest, most potent harvest by tormenting your marijuana plants makes about as much sense as the idea that starving your marijuana plants during their last weeks of life produces the heaviest, most potent harvests. It’s counterintuitive.

What really happens when a grower does deliberate harm to their marijuana plants by underwatering or underfeeding is that the cannabis plants respond by fading faster than they normally would. Flowers and resin glands shrink, the leaves show nutrients deficiencies, etc.

If bloom phase is shorter under these conditions, it’s because the plants are giving up. They’re being treated badly at the end of their lives, similar to how elderly people are often treated in nursing homes.

Ironically, many of the tactics growers use to shorten bloom phase decrease plant metabolism and floral maturation rate, leading to a longer bloom phase, lower harvest weight, and less cannabinoid percentages.

So we’ve seen that the common tactics for shortening bloom phase don’t work and are often detrimental. Is there anything you can do to make bloom phase as short as possible?

The best thing you can do is give your plants the optimum environment, lighting, reverse osmosis water, fertigation cycles, root zone size and feed program for their entire life cycle.

Adopt a calmer attitude towards bloom phase. Like fine wine, your marijuana buds need time to ripen and mature so they’re as heavy, tasty, aromatic, and potent as possible.

This attitude vanquishes impatience, respects your cannabis plants, and relies on the breeder’s bloom phase duration estimate along with your personal examination of resin glands.

You harvest when 15-25% of your resin gland heads are cloudy or amber and the stalk/head resin gland structures are falling apart, which is an indicator the flowers are ripe and ready for harvest, and no sooner. This is how you get your heaviest harvests and highest cannabinoid percentages.

One final note—there may be times when you desperately need your bloom phase to hurry up and finish. In that case, you could let your buds and resin glands mature as long as you can give them, and then harvest some or all of the buds “early.”

Some marijuana growers do this anyway, by engaging in incremental harvesting. This happens when you start harvesting a few buds off each plant beginning 10-14 days before culmination of the strain breeder’s predicted bloom phase duration.

In some situations, you find out that the buds harvested “early” give you a better high than buds harvested at peak ripeness. In other situations, the early-harvested buds produce a high that’s too light and edgy. Because the buds and resins haven’t had time to fully ripen, you tend to get a thinner, shallower, less-impactful high, and your harvest weighs less.

As always, the staff of Growing Marijuana Perfectly is constantly scanning scientific cannabis research. If we ever find a safe, reliable way for you to accelerate marijuana bloom phase without using toxic substances or losing harvest weight or resin percentages, you’ll be the first to know! And here’s some entertainment while you’re waiting…