Does a strain’s genetics deteriorate as clones are made from clones over many generations?John Gentry

Ed: Clones taken over many generations do not deteriorate. The idea that either vigor or characteristics change over time is not true. The big danger is that plants may become infected with a virus. The longer a plant or succession of plants is alive the more likely that is to happen.


I have a Critical Jack plant in a greenhouse, It was growing too tall so I cut off the top 20 cm. and bent the other branches because they were touching the plastic wall. What should I do?Raúl Rodriguez

Ed: The plants are too big for the greenhouse and have to be pruned and thinned. Start at the bottom. Remove all thin branches and branches that are in shadow as well as any yellow leaves. Work your way up the plant removing thin branches topped with thin buds that will never amount to much. As you get nearer the canopy you will notice that some buds are shaded and will add little weight to the yield. Removing these extraneous branches gives the important branches more space. Now lets work on the important branches with the big buds. If they are tangled, try to straighten them up so that each plant’s branches stay within their assigned space. This helps stop one plant from casting shadows on another. Cut away any large fan leaves that create shadows on the buds. Help branches support heavy buds using Monkey Ties, stakes, basket holders, or netting. Direct branches to unoccupied spaces. To help bend a branch, take the stem between thumb and forefinger. Gently squeeze as you roll it between the fingers. When it is more bendable set it in position. The stem will repair the damage within a few days.


The indoor garden is flowering under 12/12 lighting. 40 minutes before the lights are scheduled to turn I peeped inside room from a darkish hallway for10 seconds. No light touched the plants but I’m wondering if I ruined the buds because they could turn hermy. Is this a problem?Sybil

Ed: It is very unlikely that opening the door to light from a dark space will affect the buds. Even if they did receive light it would not be very damaging be- cause they were exposed towards the end of the dark cycle, not at the beginning, when it would delay sending them into the critical time period. If the buds were close to maturity the breach would have little to no of an effect.


I’ve seen educational programs online such as Cannabis Training University, as well as brick and mortars such as Oaksterdam University. Are these programs legitimate? In the United States do employers seek out their grad- uates? I live in Spain. Do you think it would be useful for me to take these classes?Ryan Colburn

Ed: Yes, they are legitimate and they offer valuable information. There are a number of institutes offering training in various sec- tors of the industry from cultivation and manufacturing through running businesses and financing.

Graduates of these programs are preferred candidates by em- ployers and are useful in getting a start in the industry. Since the industry has matured more in the U.S. than in countries in Eu- rope, the experience that these courses provide will be useful in some of the nascent legal-industrial models in Europe.

Before choosing an institute, vet it. How long has it been in business? Are its instructors well respected? If you know any alumni, ask them what they think of their training.


I have been using blackout curtains in my greenhouse for more than a month so the plants get 12 hours of darkness daily. The plants are halfway through flowering. There are still 14 hours of daylight. If I quit using the curtains will the plants continue to flower or revert back to vegetative growth again?Maui Rasor

Ed: If you are growing a typical hybrid the plants will continue to flower under 14 hours of light (10 hours darkness) and finish at about the same time as they would less than 12 hours of darkness. Plants that are sativa dominant may start to revert to vegetative a bit before they resume flowering.

In Hawaii, on June 22, the longest day of the year, the dark period is just under 10 hours and each day after that the days shorten by about 2 minutes.This is just on the cusp of the critical dark period required for flowering for many varieties. However, plants will be sensitive to the small daily increase in dark period.

In his book, Marijuana Flower Forcing*, Tom Flowers contends that interrupting the dark cycle for a few days in the middle of flowering causes the flowers to renew juvenile flower growth, resulting in larger buds although ripening is delayed slightly. He reported that results varied depending on variety. *Quick American Archives, 1997


What time of day should we harvest outdoor plants?Chip & Jacqui

Ed: The best time is before dawn.The plants have been producing THC and terpenes all night and they are at peak levels and they have not been sending vast quantities of water at the rate they do when they are photosynthesizing so they are dryer. Once the sun comes up the leaves’ surface temperature rises, causing terpenes to evaporate and fill the air with their pun- gent odors. At the same time, the sunlight itself degrades some cannabinoids.


Caterpillars are attacking my plants that are in mid-flow- ering growing outdoors. Can I spray BT to get rid of them?Sharon

Ed: Yes. Bacillus thuringiensis var. kurstaki (Btk for short) is a bacterium that infects only caterpillars.

When it’s active in the host’s gut it releases a toxin that kills it.

The bacterium is considered harmless to humans and degrades in less than a week in the presence of sunlight. There are many brands of this insecticide, some of which are OMRI certified.

Unfortunately, many cannabis testing labs that test for bacteria include these in the count, making the “bacteria level” unacceptably high.


My plants are almost ready to harvest but it’s raining now and intermittent rain is expected for the next week. Do I cover them or not?Morals

Ed: Covering the plants won’t help because the humidity enables mold and bacteria to thrive. If you leave the plants standing wheth- er covered or not, by the time you harvest a good portion of the crop will be infected.

Harvest the plants now and place them in a warm room at about 26.0°C with good air circulation and a room dehumidifier until the rain has been evaporated, then lower the temperature to 21.0°C with 50% humidity until the buds are dry.

The low temperature keeps the mono-terpenes from evaporating. Manicure after the plants have dried.


I am growing in my back yard. Last night we had heavy winds that broke a lot of branches and left several of the plants leaning. It also knocked down my greenhouse and scattered the plants I had hanging inside it. The plants are still 2 weeks until they are fully ready. What should I do?Courtney Thomas

Ed: First, pick up the pieces. Collect the salvageable harvested material that was knocked down and find another place where it can hang to dry. Collect all broken branches as you remove them from the plant. Although they are still 2 weeks from ripening hang them to dry as well. They can be used for concentrates.


With plants flowering in the late stages, what effect will a light frost have? The lows hit 0 to -10 for a couple hours.Dj

Ed: An occasional light frost will not hurt a nearly mature plant but it will set its growth back. There might be slight tissue damage, and growth and ripening cannot proceed until the temperature reaches 20.0°C-21.0°C.

Spray an anti-fungal protectant on the leaves around the buds.


The plants are about 2 weeks from ripening. They are under a 250-watt metal halide lamp (MH). The ballast can switch to power a 400-watt lamp. Would it be good to switch to a 400-watt lamp now? Would they finish faster, yield more or be more potent?Silly Willy

Ed: MH lamps emit a significant amount of UVb light, which stress- es plants resulting in increased potency and higher terpene levels.

Adding additional watts, which will increase light intensity, even late in flowering, will increase growth by providing additional energy for photosynthesis.

This increases production of sugar, speeding up plant processes including growth and ripening and resulting in larger buds in less time.

The additional UVb light will increase stress, resulting in higher levels of THC and terpenes.

Remember, terpenes are volatile at low temperatures, in the low 20’s so keep the leaf temperature at the top of the canopy at about 24.0°C.

Use a surface temperature thermometer to determine the leaf temperature, then adjust room temperature accordingly.

Watch out for excess leaf stress that could cause leaves to wrinkle or curl, raise the light if they do.


I have been growing outdoor plants from dispensary clones for several years now in Oakland with no prob- lems. This year I put some plants out in the late spring and five out of the six started budding prematurely in June and then started to develop bud rot. Sadly, I had to dispose of them. Only one of them is doing well. Any clue what caused the problem so I can avoid having that occur in 2017? I am thinking I put them in the ground too early but that was the time of year that I have done it previously with no such early buds or rot.Bill Debould

Ed: The clones were grown under a regimen of continuous light. When they were placed outdoors in early June they received about 14 hours 45 minutes of light and 9 hours 15 minutes darkness.

In indica dominant varieties this may be long enough to trigger flowering. Combined with the sudden increase in dark period, the plants slipped into flowering.

The sativa required a longer dark period and was more resistant to flowering, although you might have noticed sporadic flowers among its vegetative growth.

To prevent early flowering, use a warm-white fluorescent or an HPS lamp periodically through the night for just a short pe- riod- a few minutes, enough to break up the dark period. Think of the light as a spray of water and that you have to “wet” all the leaves with light. Each time there’s a “light break” interrupting the dark period, the plant starts the countdown for the critical time period over.

Next year you could try planting a number of indica-dominant plants that are either small or that have been grown out a little and let them flower.

Plant in early April or May depending on climate and weather, harvest in late May or June. The sun’s increasing intensity and its higher UV light level will supercharge the buds’ late growth.

In some parts of Europe’s southern tier, outdoor growers can use winter’s natural light deprivation to manipulate flowering time. The same techniques can also be used in greenhouses.