Ask Ed

Questions and Answers with the Godfather of Grass

My plants are about 3 feet tall and have immaculate looking buds on them, but I have been unable to get large and dense buds even though all the hairs and stigmas are completely red when harvested. My 4?x8? system is lit by two 1000w HPS lamps on tracks. The room stays in the mid-70?s.

Indoor Dankster,
Mechanicsville, MD

Your buds are not firming up and growing into dense nuggets because they are experiencing heat shock. There are two reasons why. First, you are cooling the room but not specifically the growing area. While the ambient temperature in the room as a whole might be in the mid-70?s, the grow space where the heat emanates from might be considerably warmer. To find out place a thermometer at canopy level inside the garden. The goal is to keep this area cool. The temperature in the aisles or outside the grow area doesn?t matter.

Another reason that the plants are exposed to heat stress is the lamps. They don?t seem to be enclosed air-cooled units. Place your hand at canopy level and let the light pass over it. You will experience a heat wave until the light passes by. This is happening to the plants every 45 seconds. An air-cooled lamp will prevent the heat surges. Aim your air-cooling efforts at the garden area of your room so that ambient temperature in the garden section remains in the low 70?s. Your plants will respond by growing big fat plump buds.


When should CO2 (carbon dioxide) be used? What is the correct amount of time it should be kept in the chamber before exhausting it?

Tommy Noe,

CO2 is one of the ingredients for photosynthesis. This is the process in which plants use light energy to create sugar from CO2 and water and release oxygen as a by-product. Under bright lights and indoor conditions lack of CO2 is often the limiting factor in photosynthesis and plant growth. When the parts per million (ppm) of CO2 is increased the growth rate climbs in a linear ratio until light becomes the limiting factor. Under 60 watts of light per square foot (psf), plants can use enrichment to 1500-2000ppm CO2 rather than the 400ppm found in the air. This can double plant growth and yield as compared with non-enriched garden spaces. Cannabis uses CO2 only during the light period when photosynthesis takes place, so enrichment during the dark period is unnecessary. It uses it during all growth stages, from seedling through bud ripening. In a garden with vigorous plants CO2 is consumed so it never needs to be exhausted. The air may be changed to eliminate heat or humidity, but CO2 never needs to be removed, just replenished. When the levels drop to 200 parts per million (ppm) from the atmospheric average of 400ppm, photosynthesis pauses until the CO2 is replaced. Conversely, when CO2 levels are raised during the light cycle, the photosynthetic rate increases. Plants can utilize up to 2000ppm and growth rates can double. When CO2 is added to the room, it will be absorbed within thirty minutes ? which is when exhaust fans typically turn on.

Large fields such as this one in Switzerland present challenges.Large fields such as this one in Switzerland present challenges.BROWN SPOTS ON PLANTS

We started plants about 2 weeks ago and recently they have developed many small brown spots on the leaves and the tops of the leaves have begun to curl under. We are currently running a 1000W MH and the room temperature stays around 80?F. We have a hydroponic system with air pumps to oxygenate the water. The plants are in trays under the light with grow rocks. What do you think could be causing these symptoms?

Fellow Grower,

Although the temperature in your room is a bit high it is not causing the necrosis and leaf curl. You mentioned that you are growing hydroponically. I suspect the plants are not getting enough calcium (Ca). Many hydroponic formulas skimp on Ca assuming that there will be enough dissolved in the water. If the water isn?t providing enough, supply it with a supplemental high Ca formula.


I live in southern Alberta and I understand that I need an extremely early strain to grow in this climate. If your strain isn?t early, are there ways around beating the frost without tarping the plants? I was told if you grew the plants very early in the season they will be more sensitive to darkness towards the end of summer and you can get a crop in. I also read that if you seed the plants they will ripen early as well, however the yield will suffer. What do you suggest?

Plains Man,

Considering all your options I think the easiest way for you to go is to change varieties to one that is adapted to Alberta?s climate. You are much more likely to have success than with any other option. Another choice is to let the plants seed just as you mentioned. They will ripen a month earlier than sinsemilla and will be seeded like Mexican. Rather than using the material as buds, grind and screen the whole plants (excluding stems) and then make water hash using bubble bags.

Crude techniquesCrude techniquesThis team of manicurists used crude techniques. They worked in inappropriate chairs, used their laps rather than a table, and had no advanced manicuring machinery. Rather than using cumbersome labor to dry and manicure, the whole crop could have been processed by three or four people using mechanized techniques. Rather than preparing buds, the whole crop can be turned into kief and hash.

18 OR 24 HOURS

I have read that you should have clones under 18-24 hours of light and then cut the light cycle down to 18 hours of light daily. Is this true? If not, how many hours of light should the plants receive at each stage?

Newark, California

Cuttings should be lit using low intensity light. This is because clones do not yet have a network of roots to provide them with water and nutrients, which limits their capacity to function. Instead of roots, clones depend on openings in the stem to take in supplies. Under low intensity lights, the clones? water intake capacity is not stressed. If they were placed under too bright a light, their rate of photosynthesis would jump but their stems would not be able to supply them with enough water and they would lose turgidity, wilt and then shrivel.

However, as long as plants receive a light that is not intense, about 10-15 watts of fluorescent or about 5-10 watts of high-pressure sodium (HPS), or preferably metal halide (MH) light, the stem can capture enough water to support growth. If the light is on 18 hours a day and off for 6 hours it will produce only 75% of the sugars, the tissue building blocks, that it would produce under continuous light. For fastest root initiation and growth, the light should be on the clones constantly.

As with vegetative plants, there may be times when using an 18-hour light cycle to moderate the growth rate of clones turns out to be useful. Using shorter light cycles can help you regulate the clones so that they are ready when you are ready to use them. Rooting cuttings under only 18 hours of light daily is also recommended as a strategy when you are planning to move the plants to an outdoor garden. When plants that were growing under continuous light are placed outdoors and suddenly receive only 14 or 15 hours of light daily, they will sometimes be shocked by this change and start to flower in response. By keeping them on an 18-hour light regimen before moving them outdoors, they are less likely to initiate flowering prematurely.

Healthy looking clones in the top of an aeroponic unit.Healthy looking clones in the top of an aeroponic unit.CLONING

I want to take cuttings from my plants. How should I trim them? What planting medium should I start them in? What fertilizer should I use and when should I use it? What should I feed the plants when they are growing vegetatively?

Gorge Grower,
Charlotte, West Virginia

Most professional cloners use either rockwool or Oasis cubes as medium, which are sterile, nutrient-free, prepare with ease, and require minimal labor compared with containers that must be filled with planting mix. However, there are many pasteurized or sterile mixes that are suitable for cloning. Some mediums include vermiculite, perlite, a mixture of the two, peat moss, or bark-based planting mixes and pasteurized planting mixes containing loam. Aeroponic and nutrient film techniques are often used for cloning. They are very easy to set up and maintain, have high success rates and speed up root initiation. Once root growth has initiated, the cuttings can be planted in cubes or soil mix for conventional planting indoors and out.

Hydroponic methods lessen the water stress that young cuttings face. Cuttings have only a limited ability to absorb water because they have been separated from the roots, their water gathering system. Heat, low humidity and intense light all create demands on the cuttings? water supplies. When the demands are greater than the stem capacity, the leaves lose turgidity and wilt. The amount of leaf tissue is also an issue. A cutting with a few small or trimmed leaves requires less water than one with large fan leaves attached. Heavily trimmed cuttings initiate root appearance and shoot growth faster than the cuttings with less pruning.

Don?t fertilize for the first three days. Just adjust the water to about 6.3pH and use Superthrive or a similar product. If the water takes a lot of adjusting you might be raising the salt levels too high. The Electrical Conductivity (EC) meter should read no higher than 0.3. A recommended ph/EC meter is the highly regarded HANNA Gro?Chek Portable pH/TDS/EC meter HI 9813-0, which retails $179. If the water is naturally high in salts, dilute it using distilled water. Hydrogen peroxide is a sterilizing agent that kills the fungi and bacteria present in water that attack plants. As a preventative, add 1 part hydrogen peroxide (H2O2) to 199 parts water. That works out to be 1 pint of drugstore 3% hydrogen peroxide to five pints of water. If you are using 10% H2O2, the dilution is one part in 19 parts water. After three days, fertilize the cuttings with a formula such as 4-7-7. The low nitrogen (N) discourages leaf growth, the high phosphorus (P) promotes root growth and the potassium (K) balances the acidity of the phosphorus. The EC should be about 0.8. Water the plants with this type of fertilizer two or three time, or as needed, over the next seven days. By this time the cuttings will have initiated root growth. It?s time to increase the EC strength of the irrigation water and change the formula to a 7-7-7 ratio, which increases the ratio of N to promote stem and leaf growth. Also increase the strength to an EC of 1.6 to 2. Once the clones are entering full vegetative growth, about a week after planting, use one of the standard vegetative growth formulas. Two factors should be used to determine the strength of the formula. The first is the preferred growth rate of the plants during the vegetative phase. Do you want the plants to grow slowly or quickly? Although you would instinctively say ?as fast as possible,? slower growth might be better for scheduling. Second, consider the amount of light the plants receive. Plants receiving a lot of light need more nutrients because they grow faster. There is an excellent article called ?Cloning For Dummies? by grow expert Jef Tek in CC #59 that will answer all your questions.

An aeroponic clone system bathes stems in fine mist.An aeroponic clone system bathes stems in fine mist.GROWING IN A WARM AREA

I live near Rome where it stays warm all year. Can you tell me when I should plant marijuana outside? What varieties should I choose?

Roma, Italy

The southernmost areas of the US as well as much of Mexico have similar environmental conditions to the area around Rome. Weather conditions in these areas are suitable for growing all year. However, the light cycle at the 38th parallel ranges from 15 hours 15 minutes on June 22, the longest day of the year, to 9 hours 7 minutes on December 22, the shortest day of the year. No matter what time of the year indica plants are placed in the ground they will soon start to flower because of the long night cycle. During the winter months, when the sun isn?t as intense, plants grown vegetatively can be moved outside to flower. Indica clones can be placed outside and prevented from flowering until they reach suitable size. The plants measure periods of uninterrupted darkness to determine when to flower. Blasting them with light each night halfway between dusk and dawn breaks up the dark period, which keeps them growing vegetatively.

Started in the late spring or summer, sativa plants will ripen in October and November. Plants started in the fall or winter will grow a bit, gradually switching to flowering as they grow. They will mature only if given enough time. Expect a 4-5 month growing period. Plants started in September will ripen in January and February, so the plants shouldn?t be started after early December or they may revert to vegetative with the coming spring and won?t ripen until the following fall.

Hybrids between sativa and indica plants will grow vegetatively in the summer and will ripen in September. When planted in the fall, winter or early spring, they will react much like indicas.


I am flowering my plants in a 5?x5? area. I know that you say for best results I should use 60 watts per square foot in flowering. That comes to 1500 watts. What lamps should I use? What wattage should they be and what other advice do you have about the lighting?

Jerry Toker,
Austin, Texas

There is no need to use any type of lights other than high-pressure sodium (HPS) lamps. These lights provide the entire spectrum of light that the plants need. There are also some HPS lights with modified spectrums, which will supply the plants with more blue light. They may increase yield. There are lots of possible combinations to get to your approximate goal of 1500 watts. Here are some, but not all: 1-1000 and 1-400, 1-1000 and 1-600, 2-600 and 1-400, 1-600 and 2-400 and 4- 400. The lamps should be mounted to a rotating light mover. Even though some of these combinations use lamps with uneven wattages, the lamps cover all the plants so they all get the same amount of light. Keep higher wattage lamps further away from the canopy than lower wattage lamps. To keep the lights from heating the leaves at the top of the canopy and causing lanky, running buds, use air-cooled lights. They keep the space under the lights cooler and divert much of the heat out of the room. To increase the yield considerably add 2000 parts per million of carbon dioxide (CO2) to the grow room. This speeds up photosynthesis, increasing the growth rate.

Nutrient flow cloning unit.Nutrient flow cloning unit.Nutrient flow cloning unit. Water in the bottom of the container is pumped up through the tube
in the center, hits the inside cover and disperses all around it, creating a constant flow of aerated water
of the stems, which are held in small skeleton cups.


I am growing a garden that is 3?x5? and 8 feet high. How much light should I use? I am only home on the weekends. Can I use a wick system to keep the plants watered? What else should I do to assure that the garden will be a success?

Jorgie Porgie,

Your garden is 15 square feet, or about 1.5 square meters. Light intensity that is over 60 watts per square foot will produce big fat tight buds. That comes to 900 watts of light. The lamp that comes closest to this measurement is a 1000-watt lamp. You could use a 600-watt lamp but the buds will not be as large and will take longer to ripen. Make sure to buy an appropriate reflector that pushes the light down to the garden. The walls should be painted white or covered with reflective material. A 1000- watt lamp produces about 3200 British Thermal Unit?s (BTU) of heat. If that heat accumulates in the room, the space would soon get very hot and adversely affect plant growth. The heat must be removed from the space. Using an air-cooled lamp solves part of the problem. Air-cooled lamps draw air from outside the room into a tube using an inline fan. The air cools the bulb and then exits through an out-take tube that exhausts outside of the grow room. The heated air is free of any telltale odors because it was never exposed to the plants in the garden space.

Another option is to have a small capacity portable air conditioner mounted above the plants and lights. It collects heat, which exits the space through a tube. This air has collected odors so it can be cleaned through a charcoal filter; then it can even be used for heating your house! Set the air conditioner in the grow room at 72?F (22?C). The air conditioner will also keep the humidity down by condensing it. Since the space will have little ventilation, it must be supplemented with carbon dioxide (CO2), which the plants use in photosynthesis. This can be accomplished using a small CO2 tank and regulator. The product CO2Boost (see the JefTek review in this issue) raises CO2 to 800ppm for one month. By using two at a time, you can get 1600ppm. Keeping the CO2 levels high promotes growth. Low levels slow it down.

You can use a wick system to keep your plants irrigated. The wick system uses a reservoir and draws water to the planting containers as needed using capillary action. As long as there is water in the reservoir the plants won?t go dry. Don?t worry about not being there to take care of your garden daily. As long as you make sure to provide the environment that the plants need they won?t miss you while you are away. In fact, the garden is less likely to become infected with pests or disease if you limit your visits.

Between 5 and 10 stems are held in each cup. The unit holds 8 cups.Between 5 and 10 stems are held in each cup. The unit holds 8 cups.SMALL BUDS

I am growing a garden with a controlled environment. I have air-cooled lights, temperature control using air conditioners, and customized irrigation. The plants look healthy and grow well. The garden suffers from only one problem. Small buds. I know it isn?t the varieties because all the plants, each a different strain, are suffering from it. Why is this happening?

Northern California

The problem is probably that you are using nutrients that promote vegetative rather than flower growth. You are probably using a fertilizer or planting medium high in nitrogen (N) rather than phosphorus (P), which promotes flower growth. A telltale sign of excess N is dark green leaves well into flowering. This usually happens in planting mix rather than hydroponics. In hydro the water/nutrient mix is changed when plants are forced to flower.

If the buds are less than halfway through flowering you can still get larger flowers and increase yield. First, remove the excess N held by the planting medium by flooding the containers with water so they drain. The N salts are soluble in water, so they dissolve and drain out. Then use a water-soluble flowering formula. The change in growth will be apparent within a few days.

In the future, don?t over-fertilize during the growth period or there will be too much residual N in the planting medium. A week before changing the light period, start using a flowering fertilizer. When the plant begins to change its growth, it will have the nutrients it needs. The flower size will increase dramatically.


I grow in planting boxes indoors. The boxes are 4?x8? and 2 1/2 feet deep. They are filled to the 2-foot mark with a planting mix containing compost, worm castings, bark and peat supplemented with guanos, cottonseed meal and kelp. The plants grow great in the mix. My problem is that it requires a lot of work and some expense to make the mix, use it once, remove it and start all over again. Would it be okay for me to use the mix over again?

Medium Crazy,
Simi, California

Yes, with a caveat. The planting mix can only be reused if the plants you are harvesting are healthy and harbor no pests or diseases. During a growth cycle the volume of the planting mix has probably shrunk a bit from its original size. This is the result of compaction, use by the plants, and natural oxidation. It should be bulked up with new enriched material. If the leaves were turning lighter green towards the end of the flowering cycle, the soil has used up much of its N reserves. Add a high N fertilizer such as bat guano or cottonseed meal.

Re-using mix has advantages over using virgin mix. Roots develop symbiotic and community relationships with mycological organisms called mycorrhizzae. These organisms must first colonize new planting material, but they are probably already present in pre-used soil. Second, some nutrients become available over time. With new mix, nutrients may still be locked in slowly available fertilizers. In older soils, these nutrients are already available. If the plants have had diseases or infections, the planting mix should not be re-used, at least not in a greenhouse or grow room. Ease of use is not worth the chance of an infection.


My two brothers and I live on a 200-acre farm that is mostly planted in corn. We would like to plant an acre or two in marijuana. How do we plant? How do we harvest? What do we do with the harvest? We don?t want to use farm labor or friends. Can we mechanize the process?

Pixie & Bros,

For an acre you will need about 11,000 seeds. You can plant seeds that are both male and female, and then in mid-July you will have to determine the sex of all the plants and pull out all the males, possibly 5,000-6,000 plants. You could use feminized seeds if you don?t want to pull out several thousand male plants. Probably the easiest way to plant is to create your own feminized seed using a small indoor grow room. Female plants are induced to grow male flowers using light stress, gibberellic acid or silver thiosulfate. The resulting seed is only female. That way, you will be able to plant seed, but won?t have the problem of sexing plants.

The seeds should be planted at about the same time as late corn on two-foot centers in rows two feet apart. They should be drilled about a half-inch deep in moist soil. By planting late, you limit the size the plants grow before they begin to flower. If you planted several varieties that have different ripening dates, you would be able to harvest and process the crop over a longer period of time so there wouldn?t be as much of a crunch. I highly recommend that you stretch the harvest out to a month or more if possible. Rather than attempting to harvest buds, the plants can be harvested for glands using a combine. Chop the whole plants into short piece silage. You will have between 20 and 30 tons (40,000-60,000 lbs.) of wet silage. It should be cooled so that it doesn?t ferment. One way would be to spread thin piles on tarps, as long as the weather is dry. If it?s wet out, a large empty barn with room dryers would help stop mold from attacking the wet vegetation.

The refining process should begin immediately. Place the still wet grass into custom sewn net nylon bags that seal with strong Velcro. Then place the bags in an industrial-size washing machine filled with cold water and ice. The glands will be in the water draining from the washing machine. It should be filtered for glands using a three-part stainless steel mesh filter. The first filter should be steel mesh, 80 lines per inch, the second filter 100 lines per inch, and the third a finer mesh of 120 lines per inch. Depending on the size of the machine, you will be able to process 100 pounds or more per twenty-minute cycle. Each pound of wet material will yield between 1 and 2 grams of dried hash. That comes to between 40,000-120,000 grams or 88-265 pounds after processing to remove the water. The 7-bag 20-gallon Bubblebag system is also up to the task if you want to process the resin heads into bubblehash at the site where the plants are harvested.

Before you plant an acre or two, try a practice run of a crop between 1/10 and 1/4 acre to get the bugs out and fine tune the system. For more about the challenges of growing thousands of cannabis plants in an illegal environment, read the Aussie Bush Paradise stories in CC #58 (part one) and #60 (part two).

Do you have a grow question (or answer) for Ask Ed? Send mail to:

Ask Ed, 530 Divisadero Street PMB-147, San Francisco, California, 94117. Email or go to

All questions featured will be rewarded with a copy of Ed Rosenthal?s book Best of Ask Ed: Your Marijuana Questions Answered. Sorry, Ed cannot send personal replies to your questions!


ok first of all you can grow

ok first of all you can grow weed plants outside for the whole time you need automatic shutters though that close and it needs to be insulated if you live in canada like me and if you use your leaf when its wet you get more of a yeild in the end i pulled 152 grams off one btach and it was so sticky i had to freeze it to chop it up cause it keep sticking to my razor blades and bags and i only have a three bag set and i just turned 17 nigger its pretty funny when people cant figure things out for themselfs your welcome

Outdoor plants already budding in May

Hi Ed,

I live in Northern California. I planted 2 cannabis plants on April 18, 2009 outdoors in my garden. They started budding about 1 month after I planted them. I have recently topped them thinking that would cause them to go back in vegatation but they still are budding up. I called the company I purchase fertilizer from and he said I planted to early and will have to wait for another month before it goes back to vegatation. I am using Grow Big and fish emultion as fertilizer. Right now the plants are approx 3 feet tall.

Also what is the best way to deal with mites or catapillars? I purchased some spray for pest but they told me to use in August when plants are budding. But as you see they are already budding.

am i making hash right

hi ed, i have been making hash for the last couple weeks but want to know for sure if im doing it right. what iam doing is freezing my bud first then grinding it in a coffee grinder and after words brushing out the resin powder to create the solid. Then i place it between waxed paper and press with a hot knife, eventually giving me a solid. is this the proper way of making kief hash? do you have any pointers?

closed grow enviroment

when growing cge do you need to use a carbon filter and exhaust fan with ducting coming round again to resurculate the air..or can you reuse the air in the growroom with airconditioners, co2 and humidifiers?

lighting for a small room

i have a very small grow room it is 5'x6' and only about 5ft. tall, I have 2 1000w hps lights and only intend on using 1 and saving the other for parts. my question is will 1 be to much? i got the lighting very cheap! everything is new ( never used ), i dont have any other options for a room and am concerened that a 1000w hps will be to much! any input will be greatly apreciated!!


Hi In the aeroponics system that you show, there is a pipe within a pipe 1 inch is there a sprayer between every plant. When packed so tightly together how does one get there to fix problem eg sprayers not working. In the bucket system where is the sprayer as in aeroponics? waves from africa


How much should a dove weigh? Prices for california. Thank you.

help harvest may have...

weird strain- claimed (and quite bs - free, actually) to be 25% NL#5 OLDShCOOL, 12.5%Grnd D ppl x grnd daddy Daddy = gr8 gens, (THERE) X 50% Agent Orange. hmmmmm.... yeah , right on!!!!!
purp, black, PINK, POTENT ganja butter fall-off, even!!

ALso, accidentally backed into a poss cross. j=kept A-99s in pots w/ mult plants of diff strns, recycled ALL soil and ROOTS, the headbands also have SMOKE ON THE WATER - dig?

I think i shld've hrvsted today and I am not even flushed but 2 days. what 2 do?
please, take mercy for the sake of POTENT and pretty (in THAT ORDER0


help harvest may have...

weird strain- claimed (and quite bs - free, actually) to be 25% NL#5 OLDShCOOL, 12.5%Grnd D ppl x grnd daddy Daddy = gr8 gens, (THERE) X 50% Agent Orange. hmmmmm.... yeah , right on!!!!!
purp, black, PINK, POTENT ganja butter fall-off, even!!

ALso, accidentally backed into a poss cross. j=kept A-99s in pots w/ mult plants of diff strns, recycled ALL soil and ROOTS, the headbands also have SMOKE ON THE WATER - dig?

I think i shld've hrvsted today and I am not even flushed but 2 days. what 2 do?
please, take mercy for the sake of POTENT and pretty (in THAT ORDER0



Recently I have change lighting system for vegatation. I now use a 2 energy saver 41's per large plant that appears to be working ok. I alternatley use the sunlight in the day room for additional lighting during the daylight hours.
I would like to know about using black light uv bulbs.Will the black light uv do any damage to the plant in short term usage of night hours? I place a small black UV light in the growing area and use it during th night time hours. I have noticed the plants perking up and more vegatation begining to grow.



Related Articles

Ed Rosenthal
Apr 13 2006
Questions and Answers with the Chief of Keef
Pete Brady
May 2 2002
Some budding books for the cannabis cultivator
Ed Rosenthal
Oct 11 2005
My biggest and best plant is in her last two weeks of flowering.