No plant is immune to potential pests and diseases. However, there are ways to give your plants the strongest start possible in order to build their resistance. Challenges like pests, disease, and nutrient deficiencies are only part of the battle. Identify your issues quickly and start remediating them as quickly as possible to avoid further damage to your plants.
As always, we suggest using a strong starting medium and a liquid biological to give your plants their healthiest start.
Pests
Pests can range from annoying to destructive, and come in many species and varieties, making the broad topic of ‘pest control’ a tricky one to combat. There are a few remedies that work for a range of critters and there are others that mainly handle one type of pest. Since pest control is somewhat curated to the pests you’re combatting, we recommend doing research, or reaching out to our experts, for a more tailored pest control recommendation. There are several general pest-control methods you can employ depending on the nuisances you’re dealing with and how you’re growing, so find the method that works best for you!
Foliar Sprays and granular biocides are usually the first ones that growers will reach for. These sprays can be used to manage existing populations, or as a preventative measure. Common sprays include pyrethrum, diatomaceous earth (granular or mixed with water) or even diluted peppermint or clove essential oils. Check use instructions before applying these to your plants, as some pest controls should not be applied when your plant is close to flowering.
Companion planting is a method of using plants that naturally attract or deter pests as a way of driving them away from the crops you’re trying to protect. Plants like marigolds, basil, and peppermint, are great at deterring pests such as aphids, nematodes, flies, and ants. There are also plants referred to as ‘trap crops’ that you grow to attract these pests away from your crops. Nasturtiums are a natural trap crop commonly used for redirecting aphid populations.
Adding predators to your grow tent may seem like a counterintuitive method for pest control (I’m getting rid of bugs by adding more bugs? That feels like too many bugs). For large scale invasions, adding a predator species such as ladybugs (manages aphids), Stethorus punctillum (manages spider mites), or Gaeolaelaps (manages fungal gnats), can quickly get existing populations under control, and prevent future populations from developing. Predator species are not the best for day-to-day pest control, as you need enough pests to act as a food stock for your bugs, but they’re an incredibly effective natural solution.
Disease
Grow tents can easily become a host for diseases, as the grow conditions that support happy plants often support happier pathogens. Powdery mildew, septoria, and bud rot can completely destroy your crop, and infect your otherwise healthy plants if not quickly managed.
In the cases of all signs of disease, isolate any infected plants and treat accordingly. Powdery mildew can be treated with a home remedy of baking soda and dish soap in many cases. For Septoria, remove infected leaves and spray with an organic fungicide containing copper or potassium bicarbonate (use caution if pairing this with a liquid biological, as fungicides do not differentiate between beneficial and harmful fungi).
Bud rot is the most difficult of these to treat, as by the time the symptoms are obvious it may be too late to save your plant. Watch for signs of mold developing on the stem inside of your bud, that becomes mushy and grey. As the rot progresses, leaves will begin to take on a yellow hue and may look wilted or burned. If your plant shows signs of bud rot, the best option is to carefully remove the bud with sterile shears, place it in a sealed bag, and remove it from your grow room.
Often the best disease control is to monitor your growing conditions. Try to avoid excessively high humidity levels, and ensure that your HVAC is functioning properly to promote proper air flow. Plants that are densely packed in your grow room can easily spread pathogens, so ensure that your plants are appropriately spaced. Growing stronger and healthier plants with a high quality mix, and utilizing diverse biologicals to combat pathogens are great ways to increase your plant’s natural immunity.
Nutrient Deficiencies
If your plants are showing signs of stress, but you can’t find evidence of pests or diseases, it’s possible that they might be experiencing a nutrient deficiency. This can be caused by a number of factors, not just by nutrient poor soil.
Beginner growers and gardeners often think that plants only really require three key nutrients: Nitrogen (N), Phosphorus (P), and Potassium (K). Though these nutrients are essential to plant growth, your plants need a full spectrum of secondary nutrients, micronutrients, and trace nutrients, for healthy and sustained growth. The characteristics displayed by your plants will change based on the nutrients your plants are missing. Some common things to look for are color changes in the leaves (especially brown and yellow colors), dry or dying leaves, or curled or warped leaf tips and shapes.
Fixing nutrient deficiencies may be as simple as adding more of a specific nutrient to your soil. Others can be fixed by adding a liquid biological to make the nutrients in your soil or nutrient program more bioavailable. When growing in IndiCanja, we recommend utilizing a liquid biological to increase nutrient availability. If adding a liquid biological to your existing nutrient program, we recommend using a ¼ strength dose of your existing nutritional inputs, and assessing your plant’s response before increasing dosage.
Environmental Stress
Cannabis plants require a careful set of growing conditions that change along their development cycle, including tailored temperature, light, and humidity levels. Depending on the stage in their development, the environment should be adjusted accordingly. For example, seedlings and clones thrive in high humidity and temperatures 68 degrees to 77 degrees Fahrenheit. As they mature, they may need less humidity and less stringent temperatures. As your plant begins to flower, low humidity and a temperature not exceeding 83 degrees Fahrenheit will provide great results.
Temperatures that are too high, and inadequate lighting, can lead to stretching—stems growing tall and skinny but weak and wobbly. For a thick and sturdy stem, providing a metal halide lamp during early stages can help, as the blue light helps keep stems strong.
Heat stress is a major concern for many cannabis growers. Fans and proper ventilation can keep hot stagnant air circulating with cooler fresh air. In some cases, air conditioning may be necessary to gain more control over the growing temperatures. As with heat stress, cannabis plants are also susceptible to lower temperatures. Anything under 59 degrees Fahrenheit can cause slow growth and raise the risk for pathogens like mold. Plants grown in lower temperatures tend to have a significant decrease in yield as well.
Use a thermometer and a hygrometer to measure temperature and humidity. Provide fans to move air around your plants and a ventilation system to circulate air out of the room. Low-heat LED grow lights can be useful as well. Pay attention to the weather reports and ensure your plants are not exposed to major shifts in temperature as much as possible.
Root Rot
Root rot is pretty self-explanatory—rotting roots. This is typically seen as brown and slimy roots, often coming with a bad smell. The plant’s leaves and stems will start to droop and wilt, and the foliage may start to yellow or lose all color. A rotten root can’t take in nutrients from the growing medium, which causes deficiencies in the plant.
This is commonly seen in hydro setups and caused by heat, light leaks, lack of water oxygen levels, or even decomposing within the reservoir. In soil, overwatering or draining issues can cause stagnant water around the roots which is a breeding ground for harmful bacteria and fungi.
Treat root rot immediately by transplanting into fresh soil and new containers. Ensure that the new pots have good drainage to avoid a repeat of the issue. Providing beneficial bacteria can help the roots to fight off pathogens and restore root health more quickly. Hydroponic setups will require disinfection and cleaning of the entire setup. A new reservoir will need to be created, and any light and heat issues will need to be addressed.
Cannabis is widely acknowledged as a difficult plant to cultivate, and is highly sensitive to changes in it's environment. When issues arise with your plants it can be tempting to reach for the conventional fix, but there are plenty of organic solutions for the common problems your cannabis may face.
For more information on supporting healthier plants, and solutions for any problem with your grow, contact our team of soil experts!