Marijuana Cultivation/Common Plant Problems

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Marijuana Cultivation

Introduction – Fundamentals – Seedlings – Vegetative Growth – Cloning – Sexing – Flowering – Harvesting – Curing – Producing Seeds – Pests and Pest Control – Common Plant Problems

Common Plant Problems[edit | edit source]

The problems that plague growers are myriad so it is difficult to say what the best approach is to this topic. Perhaps the best approach is to make this guide practical for troubleshooting purposes. To this end. You should first find the part of the plant or type of plant material that is showing a symptom that makes you think there is a problem. From there, find the listed symptom that best describes what you are seeing and you will hopefully find the problem and suggested fixes. This section is intended for troubleshooting and diagnosis. If you would like to familiarize yourself with the symptoms of the most common problems then skim seed issues, root issues, ph and water related leaf symptoms, stem issues, and problems with harvested marijuana.

Seed[edit | edit source]

Seeds are the first step for a new generation of plants. A problem there, will result in poor performance throughout the grow. The ideal seed is a dark green, almost brown and may have stripes or other markings, it is plump and firm. A slight pressure on the seed will not crush it. These things can make the difference between a small spindly plant and a vigorous healthy plant. A plump particularly ripe seed within a batch indicates improved fast growing genetics and may signify a stronger seed, more likely to survive to maturity.

Brittle/White Seed[edit | edit source]

If a slight pressure with your fingertip crushes seeds the seeds are not viable. They are immature. You should move along to other seeds, if you produced these seeds you need to be sure to pollinate the plant early in flowering and to let the seeds grow until they are starting to fall out naturally and are fully ripe and mature.

Green Seed[edit | edit source]

A green seed is simply immature. If the seed is firm and doesn't crush easily under a fingertip then it might still be saved if you do not have a dark viable seed to replace it (only use less than ideal seed if you can't avoid it). In order to save a green seed place it inside a damp paper towel in a dark warm place and check every few hours. The color of the seed will darken as it first ripens and it may eventually sprout. You should plant this seed very close to the surface if it sprouts since it may not have the nutrient stores that a fully mature seed would have. With the appropriate attention and care a green seed can achieve a plant with the full potential of the genetics.

Small Seed[edit | edit source]

Always choose the largest seeds you can but many plants simply do not produce large seeds. Some strains produce small seed exclusively.

Roots[edit | edit source]

Root are... well the root of the plant. Water, nutrients, and hormone supplements will likely be passed up from the roots into the plant proper. You need a strong, healthy, and plentiful root system to be able to pass enough nutrients and to support the plant at its maximum growth rate. Since the root structure isn't usually visible in addition to listing symptoms it is worth pointing out what roots need so you won't have these problems in the first place.

Tight Packed Roots, Curling Around the Edge of Container[edit | edit source]

This symptom is often accompanied by less than optimum growth. Your roots simply don't have enough room. Give them some more space by transplanting to a larger container disturbing the root ball as little as possible. Many people massage the bottom and sides of the root ball very gently just enough to untangle the tips but not so much as to actually break the root ball. If when transplanting you see that the roots did not take advantage of the container's horizontal space it means you didn't transplant often enough early on. You should transplant from smaller to larger container. For example, one hempy grow the ideal transplant path involved starting the clone in a small rockwool cube. When root tips were visible this was transplanted to a 16oz plastic cup. After a couple weeks this was transplanted to a half filled 2.5gal hempy bucket. A few days before flowering this was transplanted for the last time by lifting out of the bucket and filling halfway and then setting the complete root ball on top of the new grow medium so the roots could fill the entire bucket.

Sparse or Insubstantial Roots[edit | edit source]

This depends on your stage of growth. But generally speaking roots will grow well in a medium with a carefully maintained PH and lots of oxygen. This can be an early sign that you need more oxygenation. Perhaps this is caused by poor drainage in the soil (water pulls air into the pot from the top as it drains down the bottom) or perhaps you should add an air stone to your reservoir in a hydroponic system. Note that oxygen and not air is needed, it is possible to grow with your roots submersed in well oxygenated water all the time.

Slimy, Smelly Roots[edit | edit source]

Lack of oxygen has caused a condition known as root rot in which your roots have begun to rot. You can try to save this plant but you should remember that the impact on upon the results of your grow are going to be substantial and you should mentally chock it up as a learning experience at this stage. This will be accompanied by symptoms in the plant vegetable material as well.

In order to try to save the plant you should remove the plant from its container and remove all traces of rotted material from the roots the smell is very strong and will be unmistakable. Rinse the roots thoroughly with clean water and let them dry out. Replace your medium with fresh sterile medium and disinfect your container or use a new one. When the roots are dry transplant to the clean medium and clean container. Most importantly, you need to solve whatever is causing the root rot. If you need an airstone or an additional airstone then add one, remix your soil/medium for better drainage, or make your flood and drain cycles less frequent.

Stems[edit | edit source]

Your stems are the trunks of your plant, or your leaf, or your flower. Each and every stem on the plant is important and is essential to the part it connects functioning correctly. People purchasing marijuana often complain about stems in ignorance. Stems contain within them a layer that transports nutrients and another soft pulp that transports water. Because of this stems are almost entirely composed of water weight and weight almost nothing when dried. For the best end result from your harvest, both in potency and quantity you will want nice strong thick stems.

Leaning Branches[edit | edit source]

If your branches are leaning down under the weight of your flowers the best thing you can do is tie up the branches. This can be partially avoided by installing a circulating fan in an indoor grow room to simulating the wind, the movement will cause your stems to strengthen. Always try to keep branches secure when drooping or leaning happens. Securing stems and branches can help support heavy growing buds.

Thin, Spindly Stalks[edit | edit source]

The most common cause of this symptom is lack of light. If plants are not getting enough light they will stretch to the light source so you probably need a bigger light and/or need to move it closer to the plants. Early on this can be partly solved by burying the plant more deeply when transplanting. Roots will eventually grow out of the newly submerged stem. You can also help with this condition by installing a circulating fan, the fan will simulate wind and the movement will strengthen stems. A weak root system may also contribute to this problem.

Broken Stem[edit | edit source]

This was probably caused by you trying to the bend the plant to your will (literally). Its okay, don't panic the plant will probably be fine. Just tape the stem back together and support it by tying to a stake if needed to take the pressure off the break while this heals. The plant will heal itself and will have a knot where the break was located. You should allow your plant time to recover before stressing the location. If the break is not completely severed just prop it up and you should not touch it for a week or so.

Leaves[edit | edit source]

It is through its leaves that a plant will absorb light from the sun, and utilize it in the photosynthesis process, similar to a solar panel. In general terms leaves could be regarded as sensory organs, lungs and a secondary mouth. A plant's leaves are usually the first to show signs that something is wrong with it. With a few exceptions, damage to the leaf material will not recover after the problem is remedied, you should look to the new growth for signs that the problem is resolved and the overall condition of the plant should show improvement. You will not find an exhaustive list of nutrient deficiencies here only the most common and easily identified if you need advanced deficiency identification you should try asking experienced growers either in person or via the Internet, if posting via the Internet they will need pictures to diagnose the plant with any degree of accuracy.

A common mistake is to mistake a nutrient deficiency with a PH imbalance. A PH imbalance will cause your roots to be unable to take up nutrients and can even damage the roots. Anytime you see a possible nutrient imbalance such as yellowing, necrosis, or other signs of plant damage you should double check your PH before adjusting nutrients.

Drooping Leaves[edit | edit source]

The most common causes of this symptom are over and under watering. If you are using a soil grow are you allowing the soil surface to get completely dry before watering again? You should be. If in a hydroponic grow you need to take measures to get oxygen to your roots. Otherwise, water your plant. You probably got scared by all the sites telling you over-watering is the most common beginner mistake (which is true). In a soil grow you will want to fully saturate the pot with water when you water and then let the top inch or two of the soil dry out before drowning her again. As an added note, if you are using soil and it never seems to dry out then you may have purchased a bag of topsoil and not potting soil. This soil will not drain at all. You need a proper soil mix.

Broad Leaves with Edges Curled Down[edit | edit source]

This is a sign of excessive humidity. This usually won't harm the plant but less than optimal conditions result in a less than optimal growth and harvest. The width of the leaf is also determined by genetics so broad leaves alone are not a sure indicator of whether your environment is too humid.

Narrow Leaves with Edges Curled Up[edit | edit source]

This is a sign of low humidity. Like excess humidity this will not harm the plant but less than optimal conditions result in a less than optimal growth. Genetics again affect leaf broadness as well.

Yellowing of the Leaves (from the bottom of the plant upward)[edit | edit source]

This can be a sign of nitrogen deficiency or of over fertilization. If accompanied early by browning and necrosis of the leaf tips then you may be over fertilizing. Adding extra fertilizer when you are already over-fertilizing will kill a plant at any stage of growth so it is safer to flush the plant (if using a pot use three times as much water as your container size) with clean water to remove the excess nutrients. If this helps then excess nutrients are the problem. This could be because you are feeding the plant too much or if later in the growth cycle could be caused by excess nutrient salts building up in the soil. If this does not help then you may need to add more N to your fertilizer mix. These symptoms can also be caused by a PH imbalance.

It is worth mentioning that this symptom will also be seen late in flowering on many strains and is perfectly natural as the plant draws in nutrients from the leaves toward the end of its life. Some growers prefer to give extra nitrogen to slow or prevent this and others like to let nature take its course. Either will produce fine output.

Brown/Purple Spots and/or Dark Green Leaves on Stunted Plant[edit | edit source]

This is generally a sign of phosphorus deficiency. You may need to add more phosphorus to your water or you might have a PH imbalance.

Brown/Tan/Pale Spots Throughout Leaves[edit | edit source]

You may have a phosphorus deficiency or you may have contracted a pest. Refer to the section on pests for more information on detecting and removing a pest infestation.

Yellowing Between Leaf Veins[edit | edit source]

This is likely a potassium deficiency. Add to your water or correct a PH balance. Potassium can also be locked out by salt buildup so if your PH is correct you may try a flush before adjusting nutrients.

Older Leaves Yellow From the Center Outward, Leaf tips brown progressing inward, pale new growth[edit | edit source]

Look to trace element deficiency for these problems. Magnesium and Calcium are likely culprits. You can add a bit of dolomite lime to your water (1 tsp/gallon) or add a supplement such as cal-mag, or cal-max, or similar. As always with nute deficiency your problem may actually be a PH imbalance.

Leaves Turn Pale Yellow or White with Green Veins[edit | edit source]

This is a sign of iron deficiency. Add more trace nutrients or chelated iron. As always, PH imbalance could also be the culprit.

Flowers (while on growing plant)[edit | edit source]

It goes without saying that flowers are what it is all about. They are the only part of the plant that contains high enough concentrations of psychoactive compounds to be used without additional processing after drying. Flowers are also critical to seed production.

White Pistils Turn Purple/Red/Orange[edit | edit source]

Early coloration of pistils can indicate any number of issues, namely, light burn (light intensity is too severe); heat burn (heat intensity is too severe or fruits have come in contact with hot surfaces such as greenhouse plastic, etc.); pH issues (at this stage of growth, the pH of the substrate should never dip below 5.8 pH or above 6.5 pH with optimal range 5.9-6.0 pH); over feeding/excessive ppm (especially phosphorus and potassium); wind burn (excessive turbulence in the canopy); cold burn (excessive tempered air or forced air); foliar applications (foliar spraying should be avoided at all costs during this stage of growth. Water droplets act as magnifiers and compound the intensity of light, causing pistil burn. If spraying is absolutely necessary, it should be done with lights off/at dusk/sundown with fans and temperature control systems disabled. Spot treatments as opposed to comprehensive applications.); and pollination (plants have been exposed to viable pollen and/or experienced stress or photoperiodic interruptions that have caused the plant to change sex or "herm". These hermaphroditic plants are referred to as "hermies" and will produce fruit with undesirable seeds. Hermaphroditic plants should be removed from garden immediately to avoid further pollination. Viable pollen can be rendered non-viable with plain water. Seeds from hermaphroditic plants will produce hermaphrodites, but are useful in the breeding of "autoflowering" strains.) Great care should be used when diagnosing premature pistil coloration to ensure the appropriate corrective actions. Depending on strain, pistils will naturally and gradually change colors from the 4th week of flowering on. Burnt pistils suffer from necrosis, or the death of viable tissues. Burnt pistils can not be recovered. Severe burns will hinder or cessate flower growth completely. Extreme caution should be used to preserve the integrity of the plant's pistils.

Flowers are Stunted with Hard Bumps between Pistils[edit | edit source]

Your plant is likely pollinated. The bumps are seeds.

Internode Spacing is Wide and Buds are airy[edit | edit source]

This is probably caused by a wide variation between your daytime and nighttime temperature. If using lights indoor you can do a number of things to keep temperature under control. The simplest adjustment is to make sure your lights run at night when it is coolest and are off during the day.

White Fluffy or Powdery Coating on Buds[edit | edit source]

Don't mistake this with the sparkling trichomes crystals that will coat the flowers and the surrounding leaves in a fairly uniform manner. This is either mold or it looks whispy and weblike may be a pest. Either way it must be removed from your garden. If a pest refer to pest section but if its powdery mold remove it from your garden immediately. Do NOT smoke or eat moldy bud you could get sick or even die. White powdery mildew is usually caused by too much humidity. On outdoor plants, a good spraying of the plant with a properly mixed neem oil solution will grossly inhibit mold growth. Indoors, the addition of a good quality dehumidifier will likely solve the problem.

Buds Are Small[edit | edit source]

The buds are the cumulation of the entire grow and their size will reflect literally everything else. For big buds you need healthy roots to deliver lots of nutrients. You need to deliver proper nutrient levels. You need to supplement CO2 during flowering and have proper ventilization when not supplementing. You need to control temperatures. And you need to prune your plants properly, removing smaller growth with little potential so that your plants may concentrate on the main bud or buds.

Buds Aren't Sticky/Resinous[edit | edit source]

The flowers simply aren't ready yet. Let them go a little longer. An early finishing strain will take a full eight weeks of flowering and some strains will take twelve weeks. Give your plants the time they need to mature.

Harvested Flowers[edit | edit source]

Many people mistakenly believe that they are done when they harvest their flowers but in many ways the challenge is only started. Now you have a big pile of potentially usable bud and must treat and tend it to completion with out problems.

Crispy Crumbly Buds[edit | edit source]

You simply let your bud dry too much and probably too fast.

Pliable Stems with Dry Bud[edit | edit source]

There is likely more moisture on the inside. You would depending on just how dry to the bud itself is you could move on to the curing stage using a slow cure draw the moisture out from the center of the plant or let it dry longer before curing.

Powdery or Whispy Tendrils in Flowers[edit | edit source]

This is mold/mildew. You need to let your buds get more air. Moldy buds can be post-processed into water hashes or other extracts (though generous freezing is required first)

Buds Smell and Taste Like Hay/Lawn[edit | edit source]

Characteristic of immature bud. This can often be partially solved with a long slow cure.

Buds Burn down to a Hard Black Ash[edit | edit source]

Too much phosphorus left in the plant during flowering. A slow dry and long cure will help. Next time do a proper flush before harvest.

Harsh Smoke[edit | edit source]

Possible over fertilizing.

Proper slow drying and curing will give a smooth smoke. Refer to the section covering this.

Marijuana Cultivation

Introduction – Fundamentals – Seedlings – Vegetative Growth – Cloning – Sexing – Flowering – Harvesting – Curing – Producing Seeds – Pests and Pest Control – Common Plant Problems