Ask Ed

I have bought a simple hydro garden that holds six plants in a 2-foot by 3-foot area. What type of lights should I get?


The most efficient light source for both vegetative and flowering stages is the high-pressure sodium (HPS) lamp. Even in their vegetative stage, plants grown under an HPS lamp grow faster than plants grown under a metal halide (MH) lamp.

right: Male flowers sometimes grow on the lower nodes of the branches three and four nodes below the top of the plant. Female nodes also grow there. These flowers indicate the plant?s male gender.
Male flowers on lower nodes.Male flowers on lower nodes.
Growth and yield are determined by the interaction of genetics and environment. Some varieties yield more than others. All varieties will grow faster, yield more and mature faster the more intense the light. For this reason I recommend 60 watts per square foot (psf) of garden space. Plants can be grown under smaller wattages, however, the yield will not be as large and the buds will not be as tight or potent. If the space were lit using a 400-watt lamp the garden would receive about 67 watts psf. Using a 250-watt lamp they would receive about 41 watts psf. They would grow adequately but would not reach their potential. Using CO2 would also make a difference, even in an area as small as yours. CO2 enrichment allows plants to utilize light more efficiently. The result is increased plant growth, higher yield and reduced ripening time.


How can you tell the difference between male and female plants? Is there a way to tell at an early age? I don?t want my beautiful bud to get pollinated.

Dale S.,

Sometimes in young plants a single flower grows at the node, a few leaves down from the top leaf. (See photo) This is often referred to as an indicator flower because it shows the plant?s sex.

At the node (intersection) of a young plant you will find either two nubs developing or two tiny indicator hairs. The nub intersections would usually indicate the plant is male. Two tiny hairs or hair-like pistils at the node usually indicate female sex. The sex of a cannabis plant is always changeable, because cannabis is very intelligent and understands what is happening in its surroundings. If there are no males near to fertilize, a female will try to become one by going hermaphroditic.

Massive Swiss greenhouse.Massive Swiss greenhouse.right: There are at least one thousand plants in this massive greenhouse. These are males being grown for breeding in Switzerland.


My plants have recently been victimized by ?damping off?. Seven to ten days after sprouts emerge, fungus attacks the stem; they bend, never to recover. After research, I tried all the recommendations: sanitize the environment, soak seeds in mild bleach solution, use sterile soilless germination medium, and Safer? fungicide spray ? all with no effect. Is this disease airborne or is it only spread in soil?

Floppy Sprouts,

Several different organisms cause stem rot. If the soil is warm, above 70?F, the culprit is probably Rhizoctonia solani. Its symptoms are lesions in the stems at the soil line. Pythium spp. are active in cool wet soils, and are often associated with poor drainage. The stem turns black and slimy slightly above the soil line. Phytophthora spp. usually attack adult plants but may also attack stems of seedlings, causing brown to blackish rot similar to Pythium. It may also be caused by Fusarium, Sclerotinia, Sclerotium, Botrytis or other species. All of these organisms are found in soils and remain in dormant stages almost indefinitely until conditions appear that are favorable to their growth. They are easily transported from contaminated soil and plant matter by dirty gloves, contaminated tools and even footwear.

There are several things you can do to prevent these fungi from attacking your seedlings and cuttings. For best results, work and keep your starts in a clean, hygienic area. Wash all tools and equipment using detergent. Sterilize them with 3% hydrogen peroxide (H2O2). Use sterile or pasteurized planting mix or planting cubes. For the first few days use water with 1% H2O2. Drugstore H2O2 is 3%, so mix it with two parts water. This sterilizes the water and planting mix, killing pathogens. Seeds started outside are less likely to be attacked by stem rot. Even so, use soil or mix high in compost content or watered with compost tea to lower the chances of being attacked. This has been proven to lower rates of fungal attack. Humic and fulvic acids prevent fungal attacks and support plant immune systems to fight them off. Add these liquids to the water solution. Water early in the light cycle so plants have a chance to dry. Avoid getting the stems wet or letting them stand in water, as moisture promotes fungal activity. Give seedlings plenty of light, warm cozy conditions and nutrients so they grow fast, are vigorous and have strong immune systems.

Spices that have anti-fungal qualities, such as chamomile, cinnamon, clove and stinging nettle, can be used to prevent attack. Their powders can be sprinkled on the soil surface, or brewed into a tea that is cooled and used as a spray. Also, their oils (available in health food stores) can be diluted and sprayed on the plant. To dilute the oil, first mix it in alcohol and then add to the water, using 1-2 teaspoons per gallon. Powdered charcoal sprinkled lightly on the soil surface also suppresses the diseases.

Several organisms can be used to prevent fungal attacks that are benign to humans and pets and listed as ?bioorganic fungus suppressors?. The primary damping-off culprits are prey for other fungi commonly called mycorrhizae. The predators have different lifestyles, but all prey on Pythium, Phytophthora, Rhizoctonia and other fungi. Three species that are available commercially are Streptomyces griseoviridis, Trichoderma virens and Trichoderma harzianum. Streptomyces griseoviridis is a fungus applied after mixing in water. The spores germinate and the mycelium forms protective shields around the root system releasing root-stimulating hormones. They earn their living by trading essential nutrients to the roots for carbohydrates produced by the plant, and are the active ingredient in Mycostop?.

T. virens is a fungus that earns its living as a parasite on other fungi. It lives independently in the medium and is the active ingredient in SoilGard?. T. harzianum is a fungus that attaches to roots and lives in a symbiotic relationship with them. It forms a physical barrier to infection by coating the root surfaces and produces toxins that kill pathogens. It is available in RootShield?. By following the rules of cleanliness and hygiene and supporting your plants? immune system with fungus suppressors, you assure a successful crop.

Safe plant mobility.Safe plant mobility.right: With a single plant in each container, moving plants around or out is easily done without distrubing the system.


We are growing hydroponically using three systems. We bought them at different garage sales. One is a container with reservoir on the bottom. An air pump pushes water into a drip collar. It uses hydro- coral. Another is an ebb and flow that has rockwool cubes. We made the third one. It?s just a 4-foot kiddie pool with a pallet on it. Then we filled different sized containers with vermiculite, perlite, well turned home-made compost made from garden and kitchen scraps and some rockwool cubes we got from an indoor garden shop. The containers all have 3/8- inch braided nylon wicks trailing from the sides of the containers, through each of the four holes and into the kiddie pool reservoir. What pH levels should I keep the nutrients at?

Zen & Exodus,
Albuquerque, NM

Marijuana does great at a pH of about 6.3 in most hydroponic units. At this pH all of the nutrients are readily available and are most soluble. In the unit using rockwool cubes the pH should be lowered a bit because the cubes are not inert, they are quite alkaline and raise the pH of the environment. Try using a water solution of 6.1. I have read hydroponic manuals that call for much lower pH, as low as 5.8. However, when I experimented with these low numbers I found growth to be stunted.


Since male plants do not produce buds, if you are growing a male plant can you still produce good smoke, or are the flowers of no use?

Just Curious,
Fresno, CA

Male plants produce white or yellow flowers with five petals that release copious amounts of wind-borne pollen. As the flowers are forming, the leaves near the stalk produce glands containing THC. These leaves are not pleasant to smoke, although they could be used in extractions. The problem with allowing males to mature enough for these top leaves to become potent is that the flowers might open, releasing pollen that will affect nearby female plants. For this reason male plants should be sacrificed as soon as they indicate. The one exception is males used for breeding ? smoking the glands on the top leaves when the stalk is near ripening is good way to judge potency, which is inherited.

Figure out how much space you will need to produce your desired yield.Figure out how much space you will need to produce your desired yield.SINGLE OR MULTI-PLANT HYDRO SYSTEM

What is the difference between single or multi-plant hydro system growing? Which do you prefer?

Antonio G.
Pasadena, Texas

I am defining a single-plant hydro unit as one in which individual plants can be removed without affecting other plants in the system. Each plant is held in an individual container of some sort. Multi-plant systems have a group of plants growing in a single unit. The roots become intertwined and the only way to remove them without disturbing the other plants is to cut them out.

Single-plant hydro units are obviously much easier to deal with in some circumstances, but not in all. It is convenient to be able to remove individual plants, however, the convenience of a multi-plant system is in the ease of maintenance. Watering is much simpler, as is general care. Another advantage is that the roots have more room to spread out, even if they intermingle. A multi-plant unit can be landscaped with several varieties that have different ripening times. Each group of plants gets its day in the sun or under the light. As the earlier varieties mature they are removed, leaving more room for the later ones to spread out.


A few buddies and I have just started gathering all the stuff we need to grow some weed. We?ve got the pots and the soil, Miracle Grow? Nutrient Pro. A sales person at Walmart told us to get it for weed, but we didn?t have time to ask him about fertilizers and lights. We are planning to grow only about 6 plants in a room. What fertilizer should we use? What kind of lights and how many of them should we use?


You have forgotten the very first item you should buy before you get anything else. A good grow book. Information is the most important tool you can have. Instead of relying on the opinion of a clerk who may never have grown a plant in his/her life, use the information in a garden book specific to your purpose. Knowledge is inexpensive and invaluable. All the equipment you buy won?t do you any good if you don?t know what you are doing. The point is that an instruction manual is an integral tool of cultivation. I humbly suggest Easy Marijuana Gardening or Closet Cultivator by yours truly as accurate instruction manuals.

Bigger buds through pruning colas.Bigger buds through pruning colas.right: This plant, grown in a 6? square container, yielded large buds through pruning the plant down to three branches. the buds were kept within their allotted section in the canopy using bamboo stakes. Bigger, higher quality buds result when you reduce the number of colas by pruning.


I have some KC Brains seeds bred for outdoor use. They are high yielding 900- gram plants. I plan to construct a greenhouse to grow in. I want to know how big the greenhouse would have to be to grow 50 kilograms?

Portoro, Slovenia

Your high yield plants will produce about 300 grams per meter in a greenhouse, so you can figure it requires about 3 1/2 meters to grow one kilogram. 50 kilograms would require about 175 square meters. A 12meter by 15meter greenhouse should suffice. If it will have stationary aisles it should be somewhat larger.


I am currently looking into purchasing a light to start a small budget grow just for personal consumption. I have seen articles and ads for Fluorex? setups. They have me confused. I was planning to buy a 400-watt HPS light system. Fluorex? bulbs are supposedly full spectrum and produce little to no heat, which means you can place it just centimeters away from plants. They require little electricity compared to HPS lamps. What should I do?


The Fluorex? bulb you are talking about is a coiled fluorescent that uses 65 watts and produces 6825 lumens ? one third to one half more light per watt than most other fluorescents. If you used the equivalent wattage of a 400-watt HPS, about 440 watts, you would require about 7 lamps. They would cost about $280 with fixtures and would produce 48,000 lumens. A 400- watt HPS lamp and ballast costs about $350. It costs about 25% more than the Fluorex? units. A 400-watt HPS lamp emits about 55,000 lumens. That?s about 15% more light than the Fluorex?.

These fluorescents emit a white light similar to metal halide lamps, which is not as appropriate for flowering as HPS lamps. HPS can also be used for vegetative growth. HPS and fluorescents produce about the same amount of heat. Fluorescents seem to run cooler but they use much less current than HPS lamps. Their heat output is about equal. Fluorescents deliver the light more evenly because it comes from many point sources. To achieve the same effect, the HPS lamp must use a light mover. Considering the difference in cost and the more efficient light spread of the fluorescents, they would probably be good to use in the vegetative room or for mothers. When these lamps are produced with increased red spectrum light, similar to the warm whites in standard fluorescents, they will be suitable for the flowering room.

Forced flowering outdoors.Forced flowering outdoors.right: Starting May 15, these outdoor plants were covered every night at 6pm. This gave the plants 12 hours of uninterrupted darkness, forcing them to flower. They were harvested July 7-22. Newly rooted clones took their place and were ripe in early October.


Does real Skunk ? that actually smells like a skunk animal ? exist anymore, or have the genetics been lost? I recently bought seeds from a seed bank that were called Skunk #1. The blooms smell like a pack of Juicy Fruit gum. I?m sure I?ll enjoy this smoke, but I?m seeking (and paid for) Skunk.

Eric B.

Dave Watson of the Dutch company HortiPharm developed Skunk #1 while he was living in California. It is a stabilized strain derived from Afghani, Mexican and Colombian Gold. There may also be some Thai in the cross, but this has never been publicly acknowledged. Once hybridized, it was stabilized by inbreeding. It is a very powerful, adaptable variety and its genetics are found in the majority of modern varieties. The name Skunk was used as a marketing tool. Skunk #1 never had the acrid pungent odor of your memory, but you can look in the Afghani section of seed catalogs to find varieties with those attributes.


I have a plant that produces seeds that occasionally produce twins. One seedling is normal and the other is a miniature. I have noticed this happening before from this plant?s seeds, but one of the twins always died, and I assumed it was just a stray weed seed that got into the medium somehow. I recently germinated a twin seed and so far I have managed to keep the miniature plant alive. It is like a bonsai pot seedling. Is this common?

Minature marijuana grower,

This is very unusual and I have no explanation for it. Has anyone else seen a plant like this? If so, please e-mail me about it! [email protected]


I have 32 plants in a 4-foot by 8-foot plastic tub under two 1000-watt lamps. The plants are four weeks into flowering and have another four weeks to go. The plants are very bushy. I?ve pruned twice now- once before starting the 12/12 cycle and once about a week ago. Would it be helpful to prune off the new little flowers underneath the canopy that aren?t getting enough light to grow? Does pruning at this stage rob energy from the budding process to heal the open cuts? On some plants I used the bend-over method and have many flowers from the side stems. They are still small. Will they beef up in the next few weeks?

Budding Gardener,

The two prunings you performed on your plants, once at the induction of flowering and the other, two weeks after forcing, removed most of the adventitious branches. These small branches beneath the canopy are deprived of light so they don?t receive the light energy they need to grow large. Instead they use sugars produced in the upper canopy thus depriving the top buds of some sugars and nutrients. If the plant juices were not directed to the lower portions of the plant, they would be used to build bigger buds on top.

After the second week of flowering most varieties concentrate on bud growth rather than branching so only two prunings should be needed. If the plants are still growing small flowering branches in the lower canopy, cut them off to preserve the upper full growth potential. Buds that receive little light have low growth potential, so shaded buds are removed. All buds that are well illuminated should be left on the plant.

The branches that you bent over to provide more direct light should be treated a little differently, but the same theory applies. The difference is that some of the buds, including small ones that would have been pruned because they had been shaded, are now in the direct path of the light. They will grow larger and tighten up but they won?t grow into primary top buds. The smallest ones should be chopped, but the larger secondary buds should be left to grow.

Also, check your nutrient formula. A high level of nitrogen (N) promotes vegetative growth. Lowering the N level and raising the level of phosphorous (P) promotes bud growth.

Mature plants were harvested in mid-summer.Mature plants were harvested in mid-summer.GERMINATING SEEDS

I recently bred my own seeds. They are mature, dark brown with tiger stripes. I let them dry out for a month. I just tested my first batch between some moist paper towels. Most of them split open exposing the root tip, but none are pushing out and growing. Is there anything I can do to promote germination?

Frank O.

Germinating seeds outside the planting medium or planting block sometimes stresses seeds. They are more likely to do well in an environment where the roots can grow downward and the stem can easily grow upward, towards the light. These are all tropisms (a directional response of a plant to a stimulus) hard-wired into the plants? genetics. Stems and roots exhibit geotropisms; they are sensitive to gravity. Follow the general rules:

1. Plant the seeds in a sterile or pasteurized medium to lessen chances of encountering disease organisms that cause stem rot.

2. Plant the seeds about one quarter inch deep. If they are planted too deeply they must expend more energy to reach the surface where they can start photosynthesizing – producing the sugars required to carry on life processes and for growth.

3. Keep the soil moist for both germinating seed and seedling plants.

4. Provide very bright light to prevent stretching. Seedlings do well under the bright light of a high-pressure sodium (HPS) or metal halide (MH) lamp. They often stretch when they are germinated under fluorescent lamps because they are not receiving enough light.

5. To keep pathogens at bay during the germination process use water treated with hydrogen peroxide (H2O2). A 1% solution kills germs. Drugstore H2O2 is usually a 3% concentrate. Use one part H2O2 to two parts water. Mycorrhizae are an alternative to using H2O2 enriched water. There are many types of these beneficial fungi that live in multi-cultural communities and use various means to fight pathogens. Some form a physical barrier around the roots preventing attack. Others produce toxins or use other biological weapons to kill and digest disease organisms. RootShield?, which is composed of a bacterium, trichoderma harzianum, is another effective germicidal product.


I am growing plants in four gallon buckets, indoors. How often should I water? When should I stop fertilizing?

Rhino, CA

Plants use water for life processes as an ingredient for photosynthesis, maintaining a healthy metabolism, for cooling and for tissue building, including flower growth. When water is limited just a bit, growth slows and the plant loses vigor. When water is more severely restricted, the plant loses turgidity and wilts. For these reasons the planting medium should be kept moist during the entire life cycle of the plant. I cannot point out a specific time interval between irrigations because of the variability of conditions including light intensity, temperature, humidity, plant size, plant stage and maturity, and the medium?s water holding capacity. Check the medium using a moisture meter or by hand if you don?t have one. Does it feel moist? If not, irrigate.

About two weeks before full ripeness, bud growth slows and ripening begins. Instead of growing new tissue, the stigmas, which are the female plant?s abbreviated flowers, begin to dry and the ovary, from which the stigmas protrude, begins to swell. At the same time, and most importantly, the glands where the cannabinoids are produced and held swell and the membrane at the top of each gland stretches to hold the viscous oil. Since there isn?t much growth during this period, the plant does not need a lot of nutrients. The residual nutrients in the planting medium will provide all that?s needed during this period. You don?t need to fertilize during the last two weeks of flowering.

Mature plants were harvested in mid-summer.CANNOT SMOKE HER MEDICINE

I am a medical user of marijuana. My problem is that I cannot smoke it because it makes me cough so much I get sicker rather than better. However, when I do use it, it calms me down and allows me to sleep. Eating it takes too long for it to activate. How can I use it in a fast acting form?

Granny Green,
Delray Beach, FL

There are several solutions to your problem. Vaporizers are a method of inhaling cannabinoids, marijuana?s active ingredient, without inhaling the smoke. There are many models of vaporizers but they all work on the same principle. Marijuana is heated to the point that the cannabinoids evaporate while staying below the temperature that marijuana begins to burn. The clear, smokeless vapors are inhaled without the harsh smoke that causes the coughing-gagging reaction. Vaporizing works as quickly as smoking. There are many models available both in head shops and on the internet. The Volcano, by Storz and Bickel, is the medicinal-grade vaporizer of choice.

Using a tincture is another fast-acting method of taking your medicine. A tincture is a concentrated solution of cannabinoids in alcohol. Alcohol has the ability to pass through the mucous membranes directly into the bloodstream and carries substances it has dissolved with it. Mucous membranes comprise the inner skin found in your mouth and throat. Application is usually through an eyedropper, or a spray. When tincture drops are used sublingually (under your tongue) they quickly pass into your bloodstream. Within a few minutes you will feel their effects as they pass through the blood-brain barrier.

Another way to use cannabis is with suppositories. Dr. Mamoud ElSohley, who runs the government?s marijuana farm at the University of Mississippi at Oxford, developed a suppository but it never became popular. You can make your own using tincture or a strong concentration of marijuana, butter/oil. Just fill a gelatin capsule with the cannabinoid mix and insert up your rear end. When the capsule dissolves, the active ingredients are absorbed through the colon?s mucous membranes. Their effect comes on about one-half to one-hour after insertion. I would assume anal medicating would work faster using an eyedropper with tincture instead of the capsule.

For extensive reviews of various vaporizer models and tincture making, check out Ask Ed: Marijuana Gold ? Don?t Get Busted.


I harvested my indoor garden about three weeks ago and have been regenerating some of the plants. I also started some clones my friend gave me and some seeds from some varieties I have wanted to grow. It?s July now and my brother got the idea that we should move these plants outside in his garden on one of the more remote Sunshine Islands. Since it?s midsummer and the light is very bright and full of UV rays, I am afraid the leaves will get burned and the plants will die if I don?t acclimate them to the harsh summer light. How do I do it?

Richard the Tinker,
Salt Spring Island, BC

Before you plant outdoors you should consider that the new Canadian regime is seriously opposed to marijuana and its cultivation. They consider British Colombia a hotspot for this activity and the Sunshine Islands are known hippie hangouts, so it is somewhat likely that there will be aerial and ground surveillance of some kind this summer. If security is not an issue, moving the plants outdoors is a fine idea, especially if the plants are early ripening varieties. They will ripen by early October, before the frost and while there is still a bit of intensity and some UV spectrum (which promotes cannabinoid formation) remaining in the sunlight. To prevent sunburn you must acclimate the plants gradually. You could start by placing them in a shady area for a few days and then increasing the amount of direct light that they receive each day for a week or two. Moving from shade to scattered sunlight and then to direct sun is a typical routine.

Transplant aids such as Wilt-Pruf? and Root-Zone?, as well as other brands of anti-transpirants, create a thin barrier between the leaf and the air, effectively preventing them from transpiring water as quickly as they ordinarily would. This reduces wilting and burning. You can use the weather to your favor in deciding when the plants should make the move. Sunny days place more burdens on the plants than overcast and rainy days, so it?s best to move during a break in the sun. Plant late in the afternoon or dusk rather than early in the day. Often, the older leaves are damaged in the transition; however, the new leaves that start out in the high UV environment will be adapted to the sun and thrive. Once the plants make the transition they will grow very quickly until the shortening days force them to flower. Plants growing in high latitudes often do not ripen by the time the season ends. By blacking out the light for 12 hours each day, starting as soon as the plants have fully re-vegetated, flowering, and thus ripening can be hastened. Since you are planting outside in early July, you will probably be able to start forcing flowering by the beginning of August.

? Do you have a grow question (or answer) for Ask Ed? Send mail to: Ask Ed, PMB 147, 530 Divisadero Street, San Francisco CA, 94117, USA. You can also email [email protected]. com and check out his website

All growers with questions featured in CC will be rewarded by Ed Rosenthal with a copy of his book Best of Ask Ed: Your Marijuana Questions Answered. Sorry, but Ed cannot send personal replies to your questions!