Roots that are too shallow form a dense mat near the soil surface. Errant roots can twist, spiral and kink, and this abnormal growth can cause the plant to die in the pot or after transplanting into the garden. Imagine all your seedlings growing strong straight roots right down into the soil. That's what they can do in root trainer pots. You can grow crop plants, flowers and tree seedlings in root trainers.
Strong Root Growth
Unlike the smooth sides of traditional planting pots, root trainer pots have ridges and grooves that angle downward, training the developing roots to grow downward rather than laterally. The basic shape also differs from traditional pots. Root trainers tend towards tall and narrow, either cylindrical or rectangular. The long narrow shape encourages roots to grow deep, while the grooves and ridges guide them. Taproots grow straight and feeder roots grow dense and strong.
Pruning Roots With Air
Air-pruning doesn't involve any clippers or shears; all you need is a root trainer pot These pots have holes in their sides. As roots develop in any container some grow down while others grow out. The ones that grow out of the holes are exposed to air, which dries them. Otherwise they would circle around at inside wall of the pot and continue to twist or spiral, causing a weak root structure that can't take in nutrients or water as well as it should. New roots form to replace the air-pruned ones, adding to dense and healthy growth.
Saplings Starting on the Right Foot
Young trees put down a deep tap root early in their development. If you grow a sapling too long in a container, the tap root will grow in a circle around the bottom of the pot stunting growth and hindering the tree's chance of putting down a good strong root system once in the ground. A root trainer pot with a hole in the bottom is ideal for starting young trees. The taproot grows to the bottom and then you can transplant right away. Just don't let the tap root emerge and dry out.
Benefits and Drawbacks
You can start any type of seedling in a root trainer pot; simply use it in place of nursery containers or seed flats. Some of these pots have hinges that allow you to open the sides of the container and remove the seedling. This cuts down on the risk of damaging fragile seedlings while pulling them out of a container. One drawback to root trainers -- they tend to dry out quickly so make sure to water frequently, especially during dry weather.
How To Use Root Trainers
Design varies depending on the product maker. The cylindrical root trainers fit into a stand so that the bottom of the root trainer is suspended. When you water, excess moisture drips through the hole in the bottom. Fill root trainers with potting soil as you would a regular planting pot and plant the seeds to the specified depth for that plant.