Here is a very basic start guide to growing your own cannabis in California.
Who can grow their own?
With passage of Proposition 64, anyone in California over 21 years old can have up to six plants. If you’re a medical marijuana patient with a doctor’s recommendation, you can have as many as you and your doctor decide you need.
That said, all non-commercial cultivation for “adult use” (what it’s officially called in California) and medical use is subject to local regulations. Many cities and counties require permits even for personal use and many ban outdoor growing entirely, requiring you to grow indoors under lights. Check your locality’s rules.
Where can I grow my plants?
The best place is outdoors in sunshine and fresh air, where plants are happiest. Plant them in the spring or summer and harvest in the fall. However, if you don’t have access to garden space or your local jurisdiction doesn’t allow outdoor cannabis growing, you can grow them indoors under high-powered “grow” lights. Check with your local city or county officials to see if there are specific limits on where you can grow.
Growing any plants indoors under artificial lighting, but especially cannabis, requires some research, skill and practice. There are many books and websites dedicated to it.
We recommend outdoor growing in the normal gardening season, so most of what follows is somewhat specific to outdoor cannabis gardening.
First, some basics about cannabis plants.
Cannabis is a “genus”, a taxonomic unit used by biologists to classify living organisms, that contains several species: Cannabis indica, Cannabis sativa and Cannabis ruderalis. These interbreed freely, resulting in “hybrid” species that contain features of both parent species. (Note that Cannabis nomenclature is changing. Stay tuned.)
Cannabis has been the subject of such intensive breeding that there are virtually no “pure” sativa or indica strains. Virtually all are hybridized.
Boys and girls
Cannabis is also “dioecious”, which means male and female flowers are borne on separate plants. This may seem weird, but it is quite common in the plant world. Pistachios, date palms, stinging nettles and Gingko trees all have male and female flowers on separate plants. Just as only female pistachio trees produce nuts, only female cannabis plants produce the useful flower clusters commonly called “buds”. Male flowers are tiny and fall off once they’ve bloomed and shed their pollen.
The process of identifying which plants are male and which are female is known as “sexing”. It is an important part of cannabis cultivation that takes an experienced eye. At the nursery, we take the guesswork out of it and guarantee that our plants are all female.
While you can grow both male and female plants together, you will end up with low-quality “bud” that is packed full of seeds. By excluding the males, the female flowers will never be pollinated, allowing the clusters to grow bigger and more potent. Male plants, once identified at the nursery, are either composted or given away to medical patients who often juice the leaves.
Seed-grown or clone?
Plant Humboldt is one of the very few cannabis nurseries to offer female plants grown from seed. This is the original Humboldt grow-your-own tradition. Many cannabis farmers—old-timers and first-timers, medical users and commercial growers—still prefer seed-grown starts.
Others prefer starting from rooted cuttings, known in the industry as “clones”. Clone plants start as small branches cut from a “mother plant” and rooted in trays indoors under lights.
There are advantages and disadvantages to both seed-grown and clone-grown starts. Seed-grown plants tend to be more vigorous, but can sometimes show variation in their production and need to be sexed properly to exclude males (something we take care of at the nursery). Clones, being genetically identical to the mother plant, will produce bud with consistent look, smell and potency, but are often less vigorous plants and have specific light requirements that can be tricky for beginning growers (see below). Clones are only cut from known female plants, so all clones are female from the start.
Along with seed-grown plants, we sell clones in 4” pots that are well-rooted and acclimated to natural light and air, so they are ready to plant in your garden straight from the nursery.
Night and Day
Cannabis is an annual plant and has two seasonal growth phases: vegetative and flowering. During spring and summer (“veg” phase), the plant puts on extensive leaf and stem growth, often in massive amounts.
As the days get shorter and nights get longer in late summer (August in the Northern Hemisphere), the plants are triggered into flowering phase (“budding”). If you’re an outdoor grower, you will typically plant in the spring and harvest in the fall, whether you’re starting your plants from seed or clone.
But, with clones there’s a catch. Clones are cut off of a mother plant that is kept indoors under artificial light for 18 hours or more per day, so the mother plant and the little cutting “think” they’re living in an endless summer of long days and therefore remain in vegetative phase. If you put that rooted cutting outside in the spring under natural daylight, when the days are short, it thinks it’s fall and time to flower. A seedling, on the other hand, will wait till the light naturally fades again in the fall to go into flower.
At the nursery, we add a few hours of supplemental light with low-wattage LEDs in order to trick the clones into thinking it’s endless summer and therefore keep them in vegetative phase. After about June 1st, you can plant a clone in your garden and it will grow normally, with no extra light needed. Before June 1st, you will need to add supplemental lighting for a few hours each evening (or early morning) or the plant will go immediately into flower and you’ll end up with a tiny plant with one little bud on it. Supplemental lighting can be as little as a single low-wattage bulb on a timer next to the plant. You don’t need expensive horticultural grow lights because all you’re doing is tricking the plant a little.
Cannabis is as easy to grow in your garden as a tomato plant, but there are some rules of thumb that will dramatically improve your yield and quality.
Soil: We recommend all first time growers use commercial potting soil, not native garden soil. Master gardeners can grow cannabis successfully in natural dirt, but beginners will have much better results with bagged soil.
Container: The bigger the roots, the bigger the plant. You can dig a large hole and fill it with commercial potting soil or use a plastic pot or fabric grow-bag above ground. The bigger, the better. Many Humboldt commercial cannabis farmers use 200 gallon (or bigger) fabric grow bags, but these are expensive and require a lot of expensive soil to fill. For a personal-use amount of finished marijuana, a 20-gallon pot will be manageable and can be put on a patio or deck. In the ground, dig a hole at least 30” across and 18” deep and fill it with commercial potting soil.
Fertilizer: You can spend $100 on a bottle of plant fertilizer with a fancy label, but there’s no need to. Any organic fertilizer will do. Some commercial potting mixes, especially those formulated for cannabis, have significant amounts of plant nutrients included. In vegetative phase, cannabis likes more nitrogen (marketed as “grow” formula fertilizers). Once your plants switch to flowering phase they need lower nitrogen but more phosphorus and potassium (“bloom” formula).
Spacing: When provided proper care and large root space, outdoor, seed-grown plants can easily grow to be eight feet tall and equally broad. In some cases they can grow twice that size, all in one short season. Even for a beginning gardener, a well-cared for cannabis plant in a 20-gallon pot can still get four feet tall by equally wide, so plan your space accordingly.
Trellising/staking: Modern cannabis strains have been bred for heavy flower (“bud”) production, often to the point where the branches will break under the weight if not supported. As the branches grow out, gently tying them to thin bamboo stakes with plant tie wire (available at garden stores) will keep them from breaking off later during flowering phase.
Cannabis is relatively pest-free, but there are a few that can ruin your entire crop, particularly mites and molds. Detailed pest control descriptions are available online, in books and through cannabis-centered grow shops. Below is a quick overview of what to look for. We recommend getting a 100x pocket microscope and checking your plants regularly, especially the undersides of the leaves where mites live. These are available at most grow shops for about $20.
Mites: Spider mites and russet mites can destroy your plants and buds. Spider mites leave white “stippling” spots where they suck the juice from the leaves. Large infestations will build up webs on the plants. (Learn to distinguish from the webs of actual spiders, which are beneficial!) Spider mites are barely visible to the naked eye, but easy to identify with a pocket microscope. There are many available organic treatments.
Russet mites are microscopic, but visible with a 100x pocket microscope. The reason they are so feared among growers is that by the time damage becomes visible, the crop is often irrecoverable. That is why it’s important to do preventative pest control and maintain constant vigilance. Don’t wait till your plants look sick! Russet mites look like tiny milky colored maggots with four legs in front. They are much harder to spot at first and, unlike spider mites, are literally microscopic and can only be seen with a 100x pocket microscope. Growers are still struggling with organic control methods. Natural insecticides based on essential oils, neem and yeast enzymes all seem to work to varying degrees. Check with your local grow shop. We recommend doing routine preventative control even if you don’t see russet mites with your microscope. The good news is that anything you do to control russets will also control spider mites, thrips, fungus gnats and most other cannabis pests.
Detailed pest control is beyond the scope of this page, but you’ll need a small hand-pump sprayer and some organic pesticide. Any good grow shop can advise you. You don’t need to spend a ton of money to do basic preventative control. At the nursery, we use various organic pest control sprays preventatively about twice/week, but most home growers won’t need near that often of a spray schedule. If you are diligent with your microscope inspections, you may not need to do much at all if you don’t see any mites.
Fungi: Powdery mildew, also known as “powder mold” or “PM”, is a fungus that grows as a white powdery coating on the leaves and buds. In small amounts it will not hurt the plant, but you don’t want to be smoking it if it gets on the flowers near harvest. It is easy to control with dilute hydrogen peroxide, potassium bicarbonate, bacterial anti-fungal solutions (e.g. Actinovate, Serenade) and many other off-the-shelf and DIY concoctions. Look online, in books or ask at a grow shop for detailed information.
Brown/gray mold, also called “bud mold” or “stem mold” is a systemic fungus that rots buds from the inside out. The best way to prevent it is to keep the plants from getting rained on during flowering phase and to provide extensive dry airflow. Once mold is identified in a bud, remove and discard the infested part and harvest the adjacent bud to limit the spread.
Harvest and storage
The rule of thumb is that when most of the pistils (commonly known as “hairs” for their appearance) on the flower clusters (“buds”) have turned from white to brown, it is time to harvest. If possible, have an experienced friend take a look and give you harvest advice, or check online.
To harvest, cut the branches, remove all the large leaves by hand or with a scissors and hang the branches in a cool, dry place with plenty of airflow but minimal heat. There is an art to proper curing and it takes some experience to get it right. The main mistakes are drying too fast with too much heat and drying too slowly which can cause mold. A cool, dry (not damp and moldy!) basement with a small fan blowing on a string full of branches is ideal unless you want to invest in specialized climate control equipment like commercial growers do.
The proper dryness is when the buds are dry, but not crispy to the touch. A good rule of thumb is to bend the stems below the flowers. If the stems snap but don’t break clean through, the flowers are probably about the right dryness. If the stems merely bend, let the cannabis dry some more. If the stems snap clean through, the flowers are probably too dry. If needed, they can be placed in a slightly more humid environment briefly to rehydrate so they don’t crumble when handled.
Once the proper dryness is reached, clip the buds off the stems and store in a cool, dry place. Glass jars in a closet are perfect. Be sure to check the moisture levels regularly to avoid mold.
Note: we would like to add links to competent online how-to resources for first-time growers (there is A LOT of BS out there!). If you have suggestions, please let us know via email to firstname.lastname@example.org