Special Topics in Horticulture: Introduction to Cannabis Growing

Cannabis Basics for Home Growers
Student Blog Post by Jennifer Pedersen and Keely Roberts

Since the legalization of recreational cannabis in 2018, many people have been more inclined to grow plants of their own. We will be sharing how-to-grow and extra helpful tips that will ensure your cannabis growing success.

Home growers these days are generally inclined to grow crops with high THC or CBD content for recreation or medicinal purposes. Alternatively, there is the option to grow traditional hemp (only containing 0.3 or less THC). Hemp is produced industrially for mass-market products such as textiles and bioplastics and has a planting rate of 400,000 per acre. It grows tall, edible seeds can be harvested from the plant and are a great source of nutrition. The stalk can be used for several other purposes as it's one of the strongest fibers in the world. As a home grower, you can use your hemp harvest for hemp seed oil, building materials, food and so much more.

There are three species of cannabis, Sativa, Indica, and Ruderalis. They can be told apart by their different leaf shapes and growing habits, as well as their effects. Indica has a shorter and wider leaf, which also translates into its growing habits of being a bushier, more compact plant with denser buds. Sativa has longer, more narrow leaves and grows quite tall making it less compact with more airy buds. Ruderalis has two fewer leaf lobes than Sativa and Indica, and the plant is significantly smaller in size compared to the other species. Indica is more commonly used as medical cannabis compared to Sativa, because it is an appetite stimulus, helps with pain relief, and is a sleeping aid. Sativa is more commonly associated with recreational use during the day due to its uplifting and creative effects. Ruderalis doesn't play a part in the ingested effects, because of its lower concentration levels of THC and CBD, but it does flower quicker than the other species and is not dependent on light scheduling to form buds.

It's important to understand that Cannabis needs lots of nutrients to thrive. You may be inclined to use fertilizers to achieve proper nutrients for your plant however if you start with rich soil, fertilizers aren't necessary. The perfect soil mix starts with equal parts vermicompost (worm poop), sunshine mix number 4, perlite, sea soil, or ocean plus earth. This mix is recommended for the best bud yield and THC percentage. Through the growing process, you may also want to incorporate some other additives. Neem meal (anti-fungal), Fly Fras (helps with pest resistance), Humic acid (helps with plant nurturance uptake), Biochar, and Minors (sea minerals). If you choose to fertilize, organic alternatives are recommended such as Gaia Green 4-4-4, Kelp meal, and Reindeer fertilizer.

Outdoor growing is helpful when it comes to space, either in the ground or in a pot. Remember the plant will grow as big as the pot will allow it. When growing outdoors it's important to know cannabis doesn't like rain but appreciates humidity. If rain were to reach a flower bud is at high risk of bud rot. Ideally, you'd want your fall to be long and dry to ensure no rain during flower production. If you are having issues with rain, a tarp, and fan are very helpful to keep moisture down. If growing outdoors your plant will want 18-20 hours of light to reach its vegetative growth and 2-8 weeks if average for peek vegetative growth. Your cannabis will then need 12 hours of uninterrupted darkness for it to begin to flower. Be sure to turn off any solar or motion detector lights near your outdoor plants. Overall most strains will talk 8-10 weeks to finish flowering if outdoors.

Indoor growing is ideal if you're looking to have flowering plants year-round. There are grow tents that come in many shapes and sizes to accommodate your spaces, all of which are reflective and have ventilation. During vegetative growth, 20-23 hours of light is ideal for increased resin production, but will still need 12 hours of uninterrupted darkness during flowering development. There are many hydroponic systems that you can buy to reduce the labor of watering, but there are also systems you can make yourself at home. One of which is called Alaska grow bucket which consists of multiple medium-sized buckets with holes in them, fabric grocery bags, one large water barrel, plastic tubing, and kitchen colanders. The water barrel is slightly elevated so gravity can allow water to flow to the float valve control at an appropriate rate and plastic tubing runs from the elevated water barrel through the float valve bucket to each grow bucket. The reusable bags line the medium-sized buckets with a colander underneath each to hold the fabric off of the bottom and create a shallow reservoir. The buckets contain lots of holes to provide ample ventilation to prevent root rot. The float valve ensures the proper amounts of water are being provided to each grow bucket, and the water barrel should be refilled around once a week.

Training your plant is an important part of growing and once your plant is about half a foot tall it's time to begin. Low-stress training is best for beginners because the plant will recover quickly and there is less room for error. One method of low-stress training is tipping, this is when you remove the very tip of the plant and pinch the top to create 2 terminal shoots, but be sure not to remove too much, so the branching has a stable base to offer support and strength. Another option is pulling and tying down the branches to create a better shape through apical dominance. This is when the plant wants to grow upwards, so it causes the side branches to take over the lead role of growing, sending off multiple terminal buds and increasing surface area. These two methods can be combined to have two stems tied down to increase the final product even further.

Some option for high-stress plant training is fimming caused by tipping the top leaves but leaving 20-30% of leaves remaining. This will allow for up to 5-6 new branches coming for your origin of tipping. Will offer you a more bushy plant with more room for bud flowers to form. Another option is supper cropping, which is caused by bending a branch as far as it will go without breaking it. This process makes your plant think it's been eaten by pests. This bend will cause its nutrients to be sent to where it thinks it has been bitten. This region will then get an increased amount of nutrients. It's best to do a branch every week so it doesn't stress out your plant. Super cropping will cause a knuckle to form that is strong and durable. Will overall help to increase the yield of a flower bud to form on the supper cropped branches.

One of the greatest challenges, when cannabis is growing are pests and diseases that can devastate your crops. It's important to have a toolbelt of repellents and pest management options so you can prevent the loss of crops. An organic bug repellent spray recipe consists of 2Tb neem oil, 1⁄2 crushed aspirin, 1tsp baking soda, a few drops of soap, and top with water all combined into a 1L water bottle. Yellow sticky traps can help will thrips and fungus gnats. Fungus gnats grow in the soil on the surface of a plan and like warm wet topsoil best. These pests will eat organic debris and roots, one way to fight this is to cover the soil with perlite or sand. Overwatering will increase the likelihood of these critters. For root aphids, you can use a botanic guard. Spider mites favor high temps and low humidity, they produce webbing in between branching or on the backs of leaves. Leaves will become stippled as the mites suck on the leaves. Bud rot which has been mentioned is caused by, cold temps high humidity, and low light, it will start in the middle biggest bud, unfortunately, it's highly spreadable, if you catch it early and close to harvest you can cut it out. Bud rot is more prominent in Indica as they have denser buds. Keeping good airflow and compost tea helps protect from excessive moisture.

Before beginning the process of drying your cannabis you want to remove all the fan and sugar leaves, but keep in mind that the sugar leaves contain highly concentrated trichomes, so they can be put aside and used for other purposes later. After that, you can hang your flower cuttings in an area that sits at 20-25 degrees Celsius with about 50% humidity, and a fan to ensure air movement. You can tell it is dry once the branch snaps when bent, if it does not snap it is not dry enough. Once dry, cure in a mason jar, and take the lid off for 10 minutes a day for a month or so. The cured flower should keep for up to two years, but to help ensure this, store it in a dark place and use terpene shields to control humidity levels within the jar.

Propagating cannabis is quite simple whether it is from cuttings or seeds. When propagating by cuttings, having a cup of water available to put your clippings in right after your initial cuts can increase your likelihood of success by preventing air bubbles from entering the stem. Cut just above a node leaving a couple of nodes on your clippings and then remove the lower leaves and immediately place them in your cup of water. Applying root hormones to your cuttings before planting them in a moistened seed starter and placing them in a humidity dome can also help raise your chances of success. Provide 20-23 hours of light and 20-25 degrees Celsius temperatures and your cuttings should be new plants in no time. When starting from seed, placing them in a moistened seed starter and humidity dome is also ideal, but it is important to keep in mind that only female cannabis plants flower. One way of preventing your chances of growing a male plant is to feminize your seeds. This can be done by regularly spraying your female cannabis plant with colloidal silver in its early flowering stage. This will cause the plant to form female pollen sacs rather than budding and when you pollinate other female plants with this pollen they will only produce female seeds, leaving you with only flowering plants.

Cannabis is an extremely versatile plant that has endless unique qualities from medicinal and recreational uses to textile properties. There are many different techniques beginner growers can try out, so what better plant is there to learn to grow?