When plants have outgrown their containers, they must be transplanted in order to continue rapid growth. Inhibited, cramped root systems grow sickly, stunted plants. Signs of root-bound plants include slow, weak growth. Severely root-bound plants tend to grow straight up with branches that painstakingly stretch beyond the sides of the pot. By the time you see these symptoms, the plant is root-bound. To check roots, remove a plant from its pot to see if roots are deeply matted on the bottom or circling the sides of the pot.
Good, strong roots must grow before cubes are ready to transplant.
When growing short plants that can be watered daily and reach full maturity in 70 to 90 days from clones or seedlings, there is little need for containers larger than approximately 3 to 5 gallons (11.4–19 L). Larger plants and mother plants will need a large pot if they are kept for more than 3 months.
Outdoors and in greenhouses, plants can grow much larger than indoors. Containers should be as big as possible to accommodate a large root mass. Big plants that produce 10 pounds (4.5 kg) of medical cannabis buds can be grown in 200- to 500-gallon (757–1893 L) containers.
Transplant into the same type or similar growing medium; otherwise, a water pressure differential (hydroscopic tension) develops between the different mediums, which slows fluid movement and root penetration. For example, when a rockwool block is transplanted into soil, it holds more water than the soil is able to hold. Roots migrate slowly into soil. Transplanting small rockwool cubes into soil works best. Each cube holds little water, and roots migrate into soil faster. Make sure to keep the soil evenly moist and the rockwool semi-moist to promote root growth into the new medium.
Starting seeds and clones in root cubes or peat pots makes them easy to transplant.
Set the cube or peat pot in a hole in the growing medium, and ensure that the growing medium is in firm contact with it. Keep root cubes and substrates evenly moist after transplanting.
Transplanting is the second most traumatic experience after severing the stem during cloning. It requires special attention and manual dexterity. Tiny root hairs are incredibly delicate and easily destroyed by light, air, or clumsy hands. Roots grow in darkness, in a secure environment. When roots are taken out of contact with the soil or an aeroponic garden for long, they will quickly dry and die.
Transplanting should involve as little disturbance to the root system as possible. Water helps the soil pack around roots and keeps them from drying out. Roots need to be in constant contact with moist aerated soil in order to supply water, oxygen, and food to the plant. But, the fine line is that these tender roots also need air (oxygen) so they are able to absorb nutrients and water.
Dip Transplants in Miticide
Dip rooted clones and seedlings into a miticidal/fungicidal solution before transplanting. Stop diseases and pests before moving plants into a clean vegetative or flowering room. Mix a fungicidal/insecticidal/miticidal dip to disinfect clones before transplanting in the growing medium. Fill a container with low (5.0–6.0) pH water and add a natural fungicide such as hydrogen peroxide in a 3 percent solution. Or include a 10 percent mix of chlorine or vinegar. Do not mix chlorine and vinegar! The resulting gas is hazardous!
Mix the clone dip, and use a rag to cover and contain soil when dipping.
Submerge the entire clone in the dip to ensure liquid covers all foliage.
Remove the clone or seedling, and gently shake off excess dip before transplanting.
Please see the Cannabis Encyclopedia, chapter 6, “Vegetative Growth” pages 63-66, for complete information on transplanting to avoid transmitting diseases and pests and a successful heavy harvest. The Cannabis Encyclopedia is available in our Headshop and at Jorge’s website, www.marijuanagrowing.com.