Cloned plants being placed into sprouting boxes at Stepwell Soil in Toronto, Ontario. (Photography by Jonathan Coward/Herb)
Cloning means growing a new cannabis plant from a cutting of another cannabis plant. Basically, you chop a branch off a cannabis plant and replant it in a new pot. It’s kind of like surgery. It’s important to carry out the operation with care. Monitor your patient. Keep your workspace clean. Use sterile tools.
Clones become extremely fragile after they’re cut. It’s the most precarious time in a cannabis plant’s life. But if you know what you’re doing, cloning is not hard. In fact, with the proper guidance, you’re almost guaranteed success.
While you can technically take clones from plants at virtually any stage of their growth cycle, for the best results, clones should be taken from mother plants (which can be female or male cannabis plants) that are at least two months old. The larger and stronger the mother plant, the better your clone will be.
Small cuttings with small stems grow roots the fastest. Smaller cuttings also require less moisture, making them easier to keep hydrated and avoid stress.
Your clone will also have more success growing roots if it’s planted in a medium that has a pH level of 5.5 to 6.6.
Your clone will be ready to transplant to a larger pot after 14 – 28 days, depending on whether your clone was taken from a young mother plant or an old mother plant. Here’s everything you need to know about how to clone a cannabis plant.
Step 1: Choose the strain you want to clone (e.g. purple og). Since your clone will share properties with the plant it comes from, you want to take a cutting from a healthy mother plant. This plant should be at least two months old for the best results.
You can help improve your chances of a successful clone by leaching the soil of your mother plant with 7.6 L (2 gallons) of water for every gallon (3.8 L) of soil each morning for about seven days. Make sure your soil has good drainage, meaning it can hold water well. Alternatively, you can mist your plant leaves with lots of plain water every morning for about seven days.
Step 2: Sterilize a sharp blade as best you can. Ideally, you should do this with isopropyl alcohol. If you don’t have that, just wash it thoroughly with dish soap. Take the blade and make a 45-degree cut into a strong and healthy branch, amputating it from the mother plant. The branch you choose should be about 3 – 6 mm thick (0.124 – 0.25 inches), and 5 – 10 cm tall (2 – 4 inches). Make the 45-degree cut right through the center of a node.
Step 3: Trim off the leaves and growth nodes near the bottom of your clone’s stem, leaving a clean length of stem at the bottom of your clone that can be planted into your soil. There should still be at least two sets of leaves at the top of your clone, above the soil line. The part of the stem where you trimmed the leaves and growth nodes should be below the soil line. If you’re not ready to plant your clone right away, put the cut end into a glass of water right away (the same as you would do with a bouquet of flowers).
Step 4: Take a red dixie cup and cut slits in the bottom to allow for drainage. Fill the red dixie cup with moist soil to put your clone into. Fill it nearly to the rim, so that there’s only about 2.5 – 6 cm (an inch or two) of space between the top of the soil and the top rim of the dixie cup. Plant your clone in the soil, and gently pack the soil around the stem. Put your cup with the clone in it on a tray so that the water that drains out the bottom doesn’t leak all over your floor.
Step 5: Mix together some water and clone rooting solution, according to the measurements provided on the package. If the solution you buy isn’t made specifically for cannabis, use the ratio of rooting solution and water for softwood cuttings. To find clone rooting solution, simply call local hydroponics stores, gardening stores, and head shops. If you can’t find any rooting solution there, you can order it online. Pour the solution into the soil around the plant to lightly water it. Pour some of the rooting solution mix into the trey, so that it rises above where you cut the slits in the bottom of the dixie cup. You’ll want to make sure your clone remains in evenly moist soil at all times. Overwatering or under watering can kill your clone so be careful.
Step 6: Put your clone in an area with low levels of light for 18 – 24 hours a day. Cool, white fluorescent lights are ideal for helping your clone to root. Put the fluorescent light 15 cm (6 inches) above the clone.
Step 7: For the first two days, keep the humidity levels in your room around 90 to 100 percent. Over the course of the following week, slowly reduce the humidity to 80 – 85 percent. This process can be made easier by purchasing a humidity tent or dome. Always leave openings for airflow. If you have no access to a humidity tent or dome, you can mist your plants lightly with water throughout the day. If at any point you notice any rotting or dead parts of the plant, cut them off.
Step 8: Keep your growing medium (like soil) warmer than the surrounding air, if possible. This will help your clones to root faster. The medium should be 5°F to 10°F warmer than the surrounding air. But be careful: if your growing medium exceeds 85°F (29.4°C), however, this will cause issues for your plant. You can warm your growing medium with a heating pad or heating cables.
Step 9: If your clones look like they’re drooping or wilting, just be patient. It takes about a week for clones to begin rooting and regain strength as their own independent plant. If your plant still looks wilted after a week, it might be a lost cause.
Step 10: Your clones should be rooted in 1 to 3 weeks. You’ll know your clone is ready to be transplanted to a larger pot once the roots begin to exceed their growing medium. For example, if you see roots beginning to penetrate the outside of their growing medium (e.g soil or rockwool cubes), you know it’s time to transplant. Yellowing leaf tips are also a sign that your clone has successfully rooted.