Since we are getting to the end of the Wet season here in the tropics, the next few weeks is about the last chance for dividing up heliconias and ginger rhizomes. It really needs to be done when the weather is still warm, and the humidity is high.
Propagation of heliconias and ginger species is usually done by dividing up the underground rhizomes from which the leafy stems and flowers grow. Lots of plants are propagated this way, but tropical plants are a little bit different, in that they often don’t have storage tubers which are a method of helping the plant survive over winter or dry seasons. Most heliconias and some gingers are native to the true tropics, where they have plentiful water and good growing conditions, all the year through.
Some gingers however, such as Curcuma, do come from areas where there is a dry season, sometimes of several months duration. You will find that these die back, sometimes completely, sometimes partially, or at least stop growing, in that time, so they sometimes have small storage tubers attached to the rhizome. These storage tubers do not have growth points on them, so it is no point in planting them, and expecting to get a new plant.
The piece of rhizome that you need to take is a section of the thick, sometimes woody, root which grows horizontally, just under the ground, from which the leaf stems grow up and the feeder roots grow down. This thick root, which is called a rhizome, can be divided into pieces, each of which needs to have a growth eye on it. With luck and a lot of TLC it is from this eye your new plant will grow.
Generally speaking, the larger the section of the root you take, the better your chances are for the new plant to grow up successfully. If possible, your piece should have several eyes, as insurance, and preferably, one of them at least should be starting to develop into a new shoot of leaves.
Roots on the new shoot are not necessary, because they usually get damaged in the digging process, and a damaged root doesn’t really serve any purpose, since it no longer is able to absorb water or nutrients. In fact you will find if you buy rhizomes from interstate or overseas (if quarantine rules permit), all the roots will be trimmed off. This is done to ensure that no soil adheres to the rhizome, which might carry pathogens, or insect pests.
After you have selected or received your rhizome, you should soak it in a weak solution of liquid fertiliser, since the skin of the rhizome can absorb water and dissolved fertiliser. This will ensure that the rhizome is fully hydrated when you plant it, and a bit if plant food will give it a boost. Plant your rhizome, with the old shoots and the eye pointing up, and the root stumps pointing down. I always prefer to start everything off in a pot, so you can keep it a bit protected, until there are signs of active growth, then when the weather is right, and the plant looks fit and healthy, it can be planted out in its spot, with a good dose of liquid fertiliser, mulch and a stake to hold it in place, while it organises its roots firmly in the ground. Don’t forget to label it, because it might be a year or two before it flowers for you, and you might need to know which is which.
First photo is a Heliconia rhizome. The stem on the extreme left is a new shoot, about 50 cm tall, and has been left intact; the next stem is a mature stem, and its leaves have been trimmed off, to prevent dehydration through the old leaves and to force the new shoot to quickly produce. It also has an active eye at its base, pointing forwards. The stems behind are old flowered shoots, which could be trimmed off and planted separately, since they may have dormant eyes which will reactivate, or maybe not. If you are buying rhizomes, this piece is unreliable.
Second photo is a red torch ginger rhizome, Etlingera elatior. The left hand shoot here is also well advanced, but the mature shoot has two very strong shoots emerging, which, barring mechanical damage, are sure to emerge as strong new growth.
Third photo is the contents of a pot of Curcuma, which was going dormant (which they will do, whether you water them or not). Here you need to select the pieces which are firm and crisp. The old roots and stems on the lower left are all that remains of last year’s planting, the newer, creamy pieces are the bulbs formed this year for next year’s growth. The little round pea shaped bulblets are the starch storage for next year’s growth, and should be planted with the bulb – they will not shoot themselves. Now you can pack these in a paper bag in a cool place, or replant them in a pot, keeping them slightly damp until they shoot. If stored, check regularly, and when
new shoots are beginning to emerge, plant them out or in pots. Don’t store rhizomes in a plastic bag – they will sweat or go mouldy.Since we are getting to the end of the Wet season here in the tropics, the next few weeks is about the last chance for dividing up heliconias