How Long Does it Take for a Hemp Plant to Fully Grow?

Growing a cannabis plant can take anywhere from 4-8 months depending on the location and type of seed used. Learn more about how long it takes for hemp plants to grow from seed to harvest.

How Long Does it Take for a Hemp Plant to Fully Grow?

Growing a cannabis plant can be a lengthy process, taking anywhere from 4 to 8 months depending on the location and the type of seed used. Generally, it takes 10 to 32 weeks, or about 3 to 8 months, for a weed plant to go from seed to harvest. Starting with a clone or an autoflowering seed can reduce this time significantly. The first step in growing a cannabis plant is germination.

This is when the seed is placed in a slightly damp paper towel and covered with a plate, or put in a glass of purified water. It's important to keep the seeds away from light during this stage. Once the seedlings emerge, they should be kept in soft lighting, such as a dimmed LED or CFL bulb, for 16 hours a day. The seedlings will have small, rounded leaves called cotyledons.

As the plant grows, fan leaves will start to appear. When you see four sets of five leaves in a fan shape, the plant should be strong enough to transition to a larger pot. This usually happens after two to three weeks. The vegetation phase is when the plants will grow quickly and many fanned stems and leaves will appear.

To help boost this growth, vegetative plants need additional nitrogen in their feeding schedules. Photoperiodic plants will flower when the daily amount of light is limited. If given enough time to grow, you'll get more buds and higher yields. Training techniques such as doubling or covering can also increase performance. In general, cannabis plants are ready to be changed after four to eight weeks.

During this stage, you should maintain a daylight schedule of at least 18 hours and use fertilizers with high phosphorus content to develop larger buds. Female plants can produce both buds and seeds when pollinated by male plants, but this will reduce trichome production. The average indoor cultivation of cannabis takes 3 to 4 months from seed to harvest. The full range is 2 to 6 months and depends on the strain and the desired size of the plants. Monitoring flowering plants is similar to monitoring vegetation, but you'll need to transition to flowering nutrients and lower the ambient temperature slightly (~ mid-70°F).

You should also be very attentive to signs of mold or hermaphroditism during flowering. A less common type of hemp is ruderalis, or autoflowering variety, which grows differently from the common light-sensitive or photoperiodic variety. These cannabis plants start producing buds automatically after about a month from germination and are ready to harvest when they are 2 or 3 months old. Knowing where cannabis plants are found in their life cycles will determine when to prune, train and trellis plants, and when to harvest. Equipped with the right tools, indoor growers like you can control these factors to reproduce optimal weather conditions and grow and harvest hemp all year round.

Jane Engwall
Jane Engwall

Unapologetic pop culture lover. Hipster-friendly zombie aficionado. Incurable bacon buff. Passionate problem solver. Incurable student.