I have some seeds I found in my desk that are more than 20 years old. Will they grow?KR M.

Ed: Probably not. Seeds expire fastest when they are kept warm. Cool (refrigerator) temperature extends their viability. Constant freezing preserves the living seed for years. Seeds kept in a desk drawer at room temperature usually have viability for just a few years. If you have a large number of seeds you could crack a few open to see if the little embryo inside is still alive fresh and alive. If they are dried or deformed, then they are dead or damaged and will not germinate.

Old seeds also take longer to germinate than fresh seeds.They may take up to two weeks to pop. The reason for this is that the enzymes and hormones used for the process have lost their chemistry or evaporated. With fewer enablers, the germination process slows.

The hormone and enzyme deficiency creates viability problems. Most seedlings die soon after germination, after their cotyledon leaves or first set of serrated leaves open. Only a small percentage of them usually get past this point. These plants are usually weak, rather than vigorous. They are not necessarily a wasted effort because they can be used for breeding.

There is a general assumption that one reason germination is prolonged is that the shell has hardened and is more impervious to water, so it has a hard time penetrating the shell. I don’t think this is so, instead that the problem is internal, with the embryo, as I described above.To alleviate some of this difficulty, it’s suggested to scuff the shells using a fine sandpaper, or to slice them slightly with a knife. Others suggest soaking them in water with additives for 24 to 48 hours to start the germination process.

On the other hand, using DMSO, which helps water penetrate both the shell and cell membranes while carrying solutes with it, some experimenters were able to increase germination rates, but the seedlings all died within days or weeks. Perhaps using DMSO and humic acid and Nitrogen (N) as described below might help with survival.

Recipes call for eight ounces water and include quarter- to half-teaspoon hydrogen peroxide, quarter-teaspoon humic acid and/or molasses or sugar. These are of marginal value, regarding germination, but the humic acid and sugars may provide some strength to the seedlings.

Plant the seeds shallowly in sterile planting media and add mychorrizae. Use the humic acid and molasses formula as well as a small amount of N such as an eighth of a teaspoon of high N fertilizer with micros, fish emulsion fertilizer, or high N guano. This will support the initial growth and may help the plants to start photosynthesizing fast to get past the vulnerable post-germination stage. Use a heat mat to keep the temperature at between 72 and 74 degrees Fahrenheit.

Expect to wait to see the seeds germinate – light spray with the water formula might help. Hope for miracles–that is, a viable plant.


I saw an electronic magnifier that plugs into your computer. You can use it to spot pests. Do you know where I can find one? Nathanial Ed: Look up digital microscopes on an internet search site such as Google or on the sales sites. You will find scopes ranging in price from a few to thousands of dollars.


Are all THC molecules the same? If so, what works in conjunction with it to change the effect and experience of one strain’s euphoria vs. another’s laid back effects if they both have the same percentage?Michael

Ed: In most cannabis, you will find mainly THC. Often varieties have small amounts of other cannabinoids. Some of these other cannabinoids, such as CBD and CBG, have calming effects, but are not psychotropic. None of the cannabinoids have an odor.

You have probably noticed that odor is related to cannabis’ effects.These odors are produced by terpenes, the ingredients of plants’ essential oils. Essential oils and the terpenes they contain are the key ingredients in aromatherapy. They can have both physical and psychological effects.

Dr. Rafael Mechoulam, who discovered THC, calls the combined effects of THC (and perhaps other cannabinoids) and the terpenes the “entourage effect.” He described what millions of marijuana users had discovered long ago: the terpenes and THC affect the body’s processing of each other and change the entire experience. Together, they are responsible for the strain’s different effects.


In your book, Marijuana Harvest, you talk about finishing products and their ingredients. I have been growing for about seven years (two) rooms using a popular brand’s planting mix and fertilizers products with success. Now I’m wondering if I‘m missing out by just sticking to one line?Papa Yahoo

Ed: If you are curious about some of the bud enhancers and finishing products mentioned in Marijuana Harvest, you owe it to yourself to experiment with them. Set aside a separate space or separate irrigation system to test them against your standard fertilizers and enhancers and make sure to keep all other conditions the same.

The manufacturers of these products depend on repeat sales. If they don’t work, who will buy them a second time?


For the past two years, botrytis has attacked my crops. I only use organic and environmental friendly products to manage this problem. It comes back right before harvest.

The plants are grown in a greenhouse with raised beds, so changing the soil is not much of an option. It is well ventilated with drip irrigation. I foliar feed at night. I have been growing the same strain for the past two seasons. Should I change varieties? If the botrytis is present once, is it always present? Should I spray the whole greenhouse with a bleach solution, but what about the beds?

The first step I’m taking is to learn about soil health and to improve the diversity of microorganisms. The second is, stopping monoculture, which I’m seeing as not the correct way of growing any crops. So, I am adding companion plants, which will work as natural pesticides and nutrient cyclers. Third, is to never let the soil be exposed, as to improve soil life and health. I’d like to think these steps I’m taking go hand in hand with preventing pest invasions and pathogens.

Is there anything more that I can do to fix the problem once and for all?Mikaela

Ed: First, let’s clear up your confusion regarding pests and diseases. Pests are animal kingdom creatures. Diseases are caused by pathogens such as yeasts, bacteria, and viruses. Botrytis is a disease caused by a fungus, Botrytis cinerea. Its spores are airborne and not related to the soil.

Botrytus is an environmental disease. As was mentioned, Botrytus is airborne and it’s everywhere, so it will come in contact with your plants. Its spores germinate easily when the relative humidity is more than 50 percent and the temperatures range from the mid-50s to the low 70s. When you foliar feed at night, you are increasing the RH to unacceptable levels. Stop increasing relative humidity by ceasing all foliar feeding from the second week of flowering.

Botrytus germinates in acidic conditions. By spraying a 10-percent milk solution or pH up on your plants, the surface pH will change to unfavorable for the fungus–alkaline. Potassium carbonate also works well as a spray up to the first three to four weeks of flowering. These are good to spray on after a rain to prevent germination of spores spread by raindrops.

Certainly improving the quality of the planting mix using bio- culture such as mycorrhizae, trichoderma, and other beneficials is a good idea, but it won’t affect B, Cinerea. However, keeping the soil loosely covered helps thwart thrips and fungus gnats, lower humidity, and increase time between irrigation. If you have a light deprivation greenhouse, set it to harvest the plants before the time they are usually attacked. If not, change to varieties that are normally harvested before Botrytus season starts.

I don’t recommend that you grow companion plants in the greenhouse. By keeping it just cannabis, you can cater to its needs and not make any compromises.

During both day and night, keep the temperature in the mid- 70s or higher, above the high end of the range for the fungus. During the day, it can climb as high as 85 degrees, increasing the plants’ growth.

If you are located in an area with high RH during the year, you might consider growing in a closed loop greenhouse. Rather than using ventilation as part of the environmental controls, condition the air in the greenhouse using air conditioning and dehumidifiers. This will eliminate the disease by lowering the humidity below 50 percent, outside the fungus’ environmental range. This also gives you a chance to clean the air so it contains fewer pathogens.

UVC light is used to control powdery mildew. The light passes over the plants for just a few seconds daily, but it kills the pathogens and its spores. There are controlled ways to use the light without coming in contact with it since it is also harmful to humans.


I am an 18-year-old high school senior living in Illinois. I want to pursue my dreams of becoming a master grower. I plan to attend Oaksterdam University, then my community college before transferring to Northern Michigan for medicinal plant chemistry. I spend hours doing research and studying, reaching out to growers, pretty much anything I can to expand my knowledge in the field of marijuana. I want to be the best I can possibly be. I was wondering if you had any advice, tips, secrets, or opinions on my plan, just anything that can help lead me in the right direction in this industry.Andrew

Ed: Your goals and plans seem reasonable to me. Illinois is opening up to legalization and so are its neighbor states, so you will be working in an industry with excellent growth. Many new people will be needed to run things. Your idea of getting formal education that is industry based through Oaksterdam and then to get a degree in agriculture and chemistry is laudable. My one piece of advice: while you are getting your education, intern with someone or an organization you respect to get a feel of things and to network.


I’m growing on the island of Hawaii. I moved my indoor vegetative outside where we have at most 14 hours of light on June 22, the longest day of the year. We turn the lights on at 9 pm, 12 am, and 3 am. How long should each blast of light be? Doing ten minutes now. Cyrano

Ed: An individual leaf needs only a few moments of red light to restart the count to a critical darkness time period.The chemistry that deals with this is changed back to the active state, which prevents flowering, with just a short light duration. The reason the lights stay on longer or move is to make sure that most of the plant receives the light. Even a gentle wind causes movement, exposing more of the plant to it. A moving light changes its angle in relation to the plant, also exposing it more completely.


I am at the force flowering stage and I have noticed that, within a few minutes of the lights going out, the plants wilt severely and when I check on them for the next 12 hours they are still wilted. After the 12 hours are up, the lights turn back on and they look great. Is there a problem here?Mike C.

Ed: Plant leaves drooping at night is not a problem. It costs the plant energy to maintain the turgidity needed to maintain leaves upright. Since they are not attempting to catch moon- rays, during the dark period, the plants let the leaves hang looser since there is no advantage to keeping them upright and it costs them energy.

This is a phenomenon common not only to cannabis, but to other plants as well, including many trees and garden plants. Using time-lapse photography, you will notice leaves in different positions during the 24-hour circadian cycle. It seems to react to light rather than time, although plants “learn the cycle” and anticipate events based on repetition.

Sometimes, leaves begin to droop on plants several hours before lights go out. This may mean that the leaves are maxed out on light for the day. They have had as much as they can handle and are not trying to capture any more for photosynthesis.


One week after adjusting the lights to 12-12 for flowering, the lights were left on for 36 hours. That was one 12-hour period that was supposed to be lit, 12 hours that should have been off but were left on and the regular 12-hour lit period again. What should I do?James Harvey

Ed: The plants will take it in stride and it will have little total effect on flower yield or quality. You should get a timer that is reliable and start using it immediately.


I have a couple of indoor plants that are five weeks into flowering. They are not developing well. The buds are tiny, very airy, and sparse. They are very different than my past results and look more like two or three weeks of flowering instead of five weeks. Upon closer inspection, I noticed one of my timers was at fault. During the 12-hour dark period, all through the five weeks, this timer was coming back on for 15 minutes after being off for three hours.James Harvey

Ed: The space would go dark, and then, three hours later, this one light would come on for 15 minutes and then go off leaving the room dark for the rest of the period (eight hours and 45 minutes). The problem has now been fixed.

Assuming the plants look like they are at two or three weeks flowering stage, should I just let them flower for another five weeks? Then they will flower for a total of 10 weeks, although the variety usually takes only eight weeks to flower. Do you think they will take more time to develop or will they just reach maturity at eight weeks?

As you described, the plants were receiving mixed signals about flowering. This has affected the growth. I think your speculation that it has also affected the chronological pattern of development is correct. The plants’ development is at an earlier stage than the five weeks the plants have spent in flowering.


The plants are two weeks into flowering and all the plants have immature seeds in every node and calyx. What can I do to save it? Is there a chemical that will stop those seeds from maturing? Other than this, things are growing faster than I’ve ever seen. The plants have never had nugs this big in week two. – Jim

Ed: First question: Have you found the culprit? Was it a male or a sneaky hermaphrodite? Or was it a result of general hermaphroditism in the group? If the latter, then there is no stopping the seeds because of continued pollination from new male flowers. The buds will best be used for concentrates. If the seeding was the result of sloppy male inspections or a few sneaky hermaphrodites, then with their elimination, any new flowers will be seedless. If it is only lightly seeded, new flowers will start growing. These flowers will be seedless, but will be part of a bud or cola that contains seeds. If the buds were heavily seeded, there is a good chance the plants will go into senescence as the seeds mature. There is no chemistry I know of which will reverse the damage caused by the pollen.


In the section called “Nutrient Deficiencies” of your Marijuana Growers Handbook, you wrote about some minerals being “mobile”, where others are not. What does the term “mobile” mean in this context? – Leslie K.

Ed: Mobile nutrients can move around the plant to the section where they can be used most advantageously. Nitrogen (N) is one such nutrient. If there is a deficiency, the plant moves the element from lower portions to the top of the canopy. Other mobile nutrients are Phosphorus (P) in the form of phosphate, Potassium (K), Magnesium (Mg), Chlorine (Cl), Zinc (Zn), and molybdene (Mo).

Immobile nutrients have a fixed position in the plant. Once they are absorbed into the tissue, they are locked in place. They are Calcium (Ca), sulfur (S), iron (Fe), boron (B), and copper (Cu).


The CO2 level in my sealed grow room goes up to 2000 ppm and higher during the dark period. Is this negatively affecting yield and quality?Victoria

Ed: I don’t think that plants will indicate a stress mode from 2000 ppm CO2 during the relatively inactive dark period. The plant absorbs CO2 only during the lit period when it is photosynthesizing.

The CO2 level rises during the dark period because it continues metabolic, that is, life processes and growth, during the dark period. It burns the sugar it has produced for energy to engage.


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.