Tammy digs deep on what’s happening below the soil and shows us how to divide roots for more plants.
Leaves, flowers and fruits are the stars of the plant world and capture our hearts with beauty and delight. But it’s the unsung heroes deep below the surface that are doing much of the hard work. Roots take up water, oxygen and nutrients for the rest of the plant, as well as sometimes storing energy. They offer anchorage and stability and support the glamourous beauty above.
The key to healthy roots is to choose the right soil because bringing them home means giving them a modified environment. Many indoor plants have roots that trace back to the rainforest, so they love premium potting-mix, rich with composted bark and organic matter. Whereas plants whose roots trace back to the desert, like cacti and succulents, love free-draining mix with sandy, grainy textures. You can find out more about your plants' preferences by checking the label or asking your local nursery. The right soil will allow the right balance of air and water to support the functioning of these very valuable roots.
Tap roots:
The humble carrot is a fine example of a tap root. It consists of one main single organ with only a few light root hairs. It’s strong and tough allowing it to penetrate down deep to access water. Much of the plant’s sugars are stored here which is why carrots taste sweet when cooked.
Fibrous roots:
Many grasses, bulbs and ferns grow fibrous roots. These are dense networks which spread out from the centre stem in search of water. Some plants may grow in clumps where an offshoot from the root or stem has the potential to be a new plant on its own. Clumping systems like zebra plant and flamingo flower can be easily divided.
Adventitious roots:
Adventitious roots are a broad category that are specialised for different functions. Orchids and Monstera have aerial roots which evolved to harvest water from the air and help climb high into the canopy. You can prune these off if unsightly. Other plants such as kikuyu grass, Snake Plant and Rabbit foot fern grow from rhizomes which are underground stems that function like roots. Rhizomes spread sideways sending up new shoots and roots at each node with all the material needed to form a new plant.
Vegetative reproduction:
Plants can create a new plant without a flower or a pollinator and it’s easy to take advantage of this to create more plants! Tammy shows us how to divide and multiply clumping roots and rhizomes.
Dividing Clumping Roots:
- Remove the plant from its container and loosen soil around the root system.
- Look carefully for a natural separation of plant material. There may be individual root systems coming from separate crowns (crown = connection point between root and stem).
- Gently tease these root systems away from each other. For smaller plants you can often do this by hand. Larger plants may be interwoven tightly, a sharp hand tool or spade may be required.
- Check each plant has a healthy set of roots and stems, discard ones damaged in the process.
- Shake off excess soil and remove dead growth or root fragments. Keep moist until planting.
- Prepare soil and re-plant at the original planting depth as soon as possible.
- You may want to cut back some foliage and water in with liquid feed to reduce plant shock.
Dividing Rhizomes:
- Look carefully along the rhizome for nodes of growth that have either a shoot or root forming.
- Using a clean sharp, non-serrated blade, cut into sections that retain one to three nodes each.
- Allow the individual plants to air-dry for a day or so before re-planting – this helps the open wound harden over and better regulate water intake.
- Plant close to the surface, only a few centimetres under the soil and water in.
- Keep moist until you can see new growth sprouting from the nodes of the rhizome. Depending on your plant, this may take 1 to 4 weeks. Anticipation is the most fun part of the process.
Plant roots are amazing! They are hardworking and often provide invisible support to the plants we know and love. Treat them well and they return the favour with lots of lush healthy growth.
