Article written by
Dipak HemrajHead of Research and Education
Content reviewed by
Dr. Lewis JasseyMedical Director - Pediatric Medicine
Table of contents
The question, “When should I harvest cannabis?” should actually be two questions:
- What time of year should I harvest my cannabis?
- At what stage in the flowering cycle is the right time to harvest my cannabis?
Harvest time depends on when you planted and whether you’re in the Northern or Southern hemisphere. The best time for harvesting cannabis depends on its growth pattern (indica, sativa, or hybrid) and how well its trichomes have developed (glandular hairs that contain cannabinoids and terpenes).
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How to Tell Cannabis Is Ready for Harvesting
When it comes to the optimal time to harvest marijuana plants, instead of looking at the entire plant, it’s more beneficial to look at the color of its trichomes and leaves and the shape of its buds.
It’s inaccurate to assume that a cannabis plant is ready to harvest because it’s in its flowering period and has started producing buds. Instead, look at the color and development of its trichomes.
Trichomes are primarily found on the plant’s flower and leaves (sometimes, they are called “sugar leaves” when covered in these substances).
Doing this with the naked eye can be hard, so use a magnifying glass, digital microscope, or jeweler’s loupe to get a closer look.
- Clear trichomes: The hairs are translucent, and the plant still produces resin in its glands. This is not the ideal time to harvest, and the plant’s cannabinoids and terpenes are not at peak concentration.
- Milky/cloudy trichomes indicate that cannabinoid production is at its peak. A cannabis plant is usually ready to harvest when half of its trichomes resemble cloudy, white hairs. This can result in a more uplifting, energizing effect for some users.
- Amber trichomes: Amber trichomes tend to indicate that the THC/THCA in cannabis has started to deteriorate, meaning there may be more cannabinol (CBN) in the flower. CBN can have sedative effects; many report feeling those effects with amber trichomes.
Many users like a mix of milky and amber trichomes, although the split proportions come down to personal preference. Some prefer all or mostly cloudy with few amber trichomes for more cerebral or psychoactive effects. Others prefer a 50:50 split between cloudy and amber trichomes for a balanced head and body effect. Others prefer 60% to 70% amber trichomes for a less stimulating, more sedative effect.
Healthy cannabis plants should have fan leaves that are a vibrant green color.
A color change to yellow or brown leaves indicates the plant has nutritional deficiencies or root rot. Feeding the plant too many nutrients (“overfeeding” or “nutrient burn”) is also a problem that can discolor and dry out the plant’s leaves. If growing in soil or a soil-coco mix, it is best to be sparing with nutrients and let the soil do most of the work.
If your plant starts to brown after all the trichomes have developed, the plant is probably dying. These plants should be harvested as soon as possible!
Different strains of cannabis can produce different bud shapes and densities. In general, cannabis buds are ready to harvest when they thicken and their white pistils start to darken.
Tips and Tricks for Harvesting
There are many different tips and tricks for harvesting, which can depend very much on the growing environment and medium. Here are some pro tips and tricks that can help regardless of your growing environment:
- Do not feed the plant any nutrients in the last week of flowering. You will want to flush out all nutrients in the growing medium so it doesn’t end up tainting the buds.
- Low-stress training (LST) can help increase the plant’s yields and vigor. LST is the practice of gently bending stems and tying them in place to increase bud production. Think of LST as “exercise” for your plant, where providing a little resistance can help it grow stronger.
- Pruning the bottom leaves during flowering can help the plant focus its energy on bud production.
- For those new to cannabis cultivation, consider the environmental factors involved in the process. Pick a forgiving variety that is well-suited to your environment. For instance, if you can only grow in small, indoor spaces in a cold climate, growing an equatorial sativa should be avoided.
Unless you’re an outdoor grower in a tropical or subtropical climate where cannabis can be planted year-round, you will usually start growing cannabis outdoors during the spring months and harvest during the fall.
In the Northern Hemisphere, the spring months are March, April, and May, and the Fall months are September, October, and November. In the Southern Hemisphere, the seasons are swapped.
The spring and summer months generally constitute the vegetative period of growth, during which the cannabis plant establishes its roots and accumulates resources needed for flowering and reproduction. Flowering is triggered when the days get shorter, usually by the end of summer or the beginning of fall.
Depending on location, 1 -2 outdoor cannabis harvests are possible annually.
You can grow cannabis indoors year-round in a grow room, although monitoring the ambient temperature outside your grow space is wise. Hotter weather may require more fans, for example.
People regularly growing indoors can expect four to eight or more harvests per year, depending on how often they plant and what strain of cannabis they’re growing. This is called “perpetual harvesting.”
How Long Does It Take for Cannabis to Grow?
Cannabis growth is divided into four stages:
- Seed germination stage: Seeds start sprouting, usually between days 7-14, although sprouting can sometimes take just a few days if the seeds are fresh.
- Seedlingstage: Lasting about two to three weeks, this is when the seed opens, and the cannabis plant starts producing leaves, starting with small, round leaves (cotyledons), then serrated leaflets. As the plant develops, it eventually produces the digitated leaves we visually associate with cannabis.
- Vegetative stage: For three to six weeks, the plant starts to establish and grow stronger roots, stores energy, and prepares for the flowering stage.
- Flowering stage: This stage lasts about six to 16 weeks, depending on genetics. The first five weeks of flowering are when the plant starts to produce flowers and buds, and the rest of the flowering period is when the cannabis ripens. Depending on genetics, the plant is ready to harvest after eight to 16 weeks.
The flowering period for indoor and outdoor cannabis plants is generally the same, lasting between eight and 16 weeks, depending on the plant’s genetics. Indoor plants usually have shorter vegetative periods, as plants can be forced into flowering by switching to a 12/12 cycle (12 hours light, 12 dark) within a few weeks.
- The flowering period for indica strains (varietals) is usually about eight weeks, although some may have shorter flowering periods (around six to seven weeks) and others longer (up to 12 weeks).
- Sativa strains, with plants that tend to be tall and lanky, can take 12-16 weeks to flower.
- Hybrid strains/varietals blend short, stout, quick-growing indicas and tall, thin, long-growing sativas and can exhibit characteristics of both. Hybrids can take six to 12 weeks to finish flowering.
Strains That Grow the Fastest
Cannabis indica and Cannabis ruderalis varieties tend to grow fast, usually ready to harvest after eight weeks of flowering. Some varieties may take as little as six or seven weeks, others nine or 10 weeks. Some examples of fast-growing cannabis cultivars include:
- Lowryder, White Ryder, Hobbit, and many other ruderalis-indica crosses
- Early Girl
- Red Dwarf
- Bruce Banner #3 Fast
- Speed Queen
Strains That Take the Longest to Grow
Sativa and sativa-dominant hybrids often take the longest to grow, usually taking 12-16 weeks to reach maturity. Cannabis strains that can take a long time to grow include:
- Neville’s Haze
- Colombian Gold
- Chocolate Thai
- San Fernando Valley OG
- Malawi Gold
- Durban Poison
The Bottom Line
Knowing the best time to harvest cannabis is an art; finding the best time to harvest a particular variety can take a few tries. You may also have personal preferences that dictate when you harvest.
For example, if you want buds with lower THC levels, harvesting when more amber trichomes are present may be best. On the other hand, if you’re looking for optimal THC content, harvesting when your plant’s trichomes are cloudy is a good idea.
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Frequently Asked Questions
How do you know when to harvest cannabis?
As a general rule, cannabis buds are ready to be harvested when 50% or more of their trichomes are cloudy or milky.
What do you do with buds after you harvest them?
Once you’ve completed your harvest, your buds must undergo a drying and curing process. This will involve items like a drying rack and containers like glass jars.
How many months does it take to harvest cannabis from seeds?
This can depend on whether you grow indoors or outdoors. Indoors can take 3-4 months to harvest cannabis from seed. Outdoors is usually around six months.
How often can you harvest a cannabis plant in a year?
Many people think that you can only harvest a cannabis plant once. However, it is possible to conduct multiple harvests on the same plant twice or more through a process called “revegging” or “regeneration.”
To do this, you must:
- Prune for a bushy plant.
- Don’t trim during flowering.
- Harvest good buds a little earlier than usual (keep the harvest window to six to seven weeks instead of eight to nine), keeping all the leaves and less-developed buds intact.
- Feed the plant nitrogen throughout its flowering period, then put it back on a 24-hour light cycle to revegetate.
You will eventually be able to harvest again. This process can be hard work and is recommended for more experienced growers. Head here for other tips on maximizing your yield.