Explosive growth is a term you sometimes see in marketing copy for cannabis-growing products.
I define explosive growth as a sudden, positive change in observable plant performance parameters. These parameters include:
- Production and maturation of new leaves.
- Thickening of stalks and stems.
- Height and diameter gain.
- Budding site development.
- Early floral development.
- Bud height, density and diameter gains.
- Resin gland development.
- Scent development.
- Root development.
- Overall rate of growth, vigor and plant health.
There are two co-occurring paths for explosive growth in a properly tuned marijuana grow room, and when you understand and coordinate them, you get bigger bang for your buck.
One path to explosive growth is the natural development and maturation timeline genetically encoded in marijuana plants.
The other path is the precise, savvy application of grow-room techniques, grow mediums, feeding programs, grow lights, light cycles, general equipment, and environmental factors to coincide with, amplify, and accelerate genetic markers. When you understand the natural explosive growth factors, you can exploit them to achieve bigger, more potent buds.
Grow-Phase Explosive Growth
Let’s examine the natural explosive growth cycle of marijuana plants. Note that timeline estimates in this explanation are generic averages; each cannabis strain and individual phenotype you’re growing may vary slightly from this timeline. Also note that this timeline is for regular photoperiod cannabis plants, not for autoflowering cannabis plants.
The first noticeable explosive growth happens after your seedlings or clones have developed sufficient root mass and leaf sets. For seedlings, it usually occurs 1–2 weeks after germination. For clones, it can occur within a few days of transferring the clone from its cutting chamber.
The indicator of explosive growth at this marker is a sudden, rapid increase in leaf development, main stalk girth, and vertical height. A plant that had been growing no more than an eighth to a quarter of an inch per day may suddenly start growing a half inch, or an inch or more per day.
This grow-phase growth spurt takes a tiny clone or seedling and turns it into a 2–3-foot tall plant in 2–4 weeks.
In the mostly invisible world of marijuana roots, a similar growth spurt mirrors what you see aboveground. Marijuana seedlings and clones that have a thin root system, with only a handful of branching tendrils in the first couple of weeks of their life, suddenly put on massive new growth in root mass density and branching.
Bloom Phase Explosive Growth & Resin Gland Maturation
The next genetically programmed explosive growth spurt happens within a few days of starting bloom phase. This is the mesmerizing bloom-phase stretch, in which plants may double or even triple their height in the first three weeks of bloom phase.
The height gain often causes problems in double-ended grow rooms, grow tents, grow chambers and any grow op where vertical space is limited. In some marijuana strains, explosive aboveground growth is accompanied by accelerated root growth at the beginning of bloom phase.
During the stretch phase of explosive growth, another type of extreme growth occurs to coincide with the height gain, and can be seen when your lengthening branches begin developing budding sites.
The number of sites, along with onset and speed of bud development, are also considered explosive growth factors. Within two weeks of bloom phase startup, well-tended marijuana plants will seem to sprout male or female flowers overnight.
The next explosive growth markers come in early peak bloom, which for most marijuana plants is 2–4 weeks after bloom phase starts.
If your plants are properly fed and cared for and have ideal genetics, you’ll see your buds rapidly putting on weight and resin glands. A bud that didn’t have any noticeable resin glands one day might suddenly have nascent ones the next.
Resin glands are the main plant structure where cannabinoids and terpenoids are formed. Note that there are three types of resin glands that develop on cannabis plants. These glands are also known as trichomes. The earliest-developing trichome is called bulbous. These are small resin glands that develop on the leaf and stay flush on its surface.
Another more numerous type of resin gland is called capitate-sessile. It’s larger than the bulbous glands and has a very short stalk that lifts it slightly off the bud surface.
The third and most well-known cannabis trichome is the capitate-stalked, consisting of a round resinous head on top of a stalk that lifts the gland off the bract. A bract is the smallest leaf in your buds and is the leaf that is most embedded in buds and least likely to be cut off during manicuring.
The elevated capitate-stalked glands are the most visible and the most easily seen with magnification and macro photography. They contain the most cannabinoids and terpenoids of any of the three types of resin glands.
Explosive resin-gland growth in size and amount is most often seen in the middle of peak bloom phase, usually around weeks 4–5 for most cannabis strains, when smaller and shorter bulbous and capitate-sessile glands suddenly give way to a sudden growth of a forest of capitate-stalked glands.
This sudden, explosive development of capitate-stalked glands is programmed genetically, but can be enhanced or deterred by your cannabis growing techniques and equipment.
The final bloom phase explosive growth event isn’t seen in all cannabis strains. It happens in the final 1–2 weeks of peak bloom, and/or the first week of late bloom phase.
For example, if you were growing a marijuana strain with a 63-day bloom phase, and if your strain’s genetics were programmed for explosive late growth, it would take place from approximately day 54 to day 63. As your plants near the end of bloom phase, the buds stop expanding in size and density and go into a holding pattern, while the cannabinoids and terpenoids ripen in the glands.
If you have late-bloom explosive-growth genetics, your plants will suddenly start adding bracts and resin glands in late bloom. Buds sometimes gain 5–15 percent more weight and size in little more than a week during their final 7–10 days before flushing and harvesting. If you use the right bloom phase supplements and flushing formula, the late growth spurt can continue right up to chop-chop day.