By: Mary Ellen Ellis
Tuberoses don’t have true bulbs but are often treated like plants that grow from bulbs. They have large roots that store nutrients, like bulbs, but these roots don’t contain all the plant parts as bulbs do. Dividing tuberose plants takes some careful maneuvering as you separate those roots to grow new plants.
Tuberose plant division can be tricky. You can end up with some useless bits of root that won’t put out new growth if you don’t do it right. Start by cutting back the browning and dying foliage. Cut it so that there are 2 to 3 inches (5 – 7.6 cm.) above the soil.
Use a trowel to dig around the plant. Take care not to damage the roots with any tools. Get the trowel right under the root system and gently lift it out from the soil. Brush off excess soil from the roots and check them over for damage, soft spots, and rot. You can cut off these damaged portions of the roots.
Cut the roots apart with the trowel, or with a sharp knife if necessary. Each section you cut should have eyelets, similar to potatoes, but can be hard to see. You’ll have to brush the dirt away and look carefully. You can replant the root sections right away, putting them in the soil to a similar depth of the original plant.
If you are in a climate that is too harsh in winter for these Mexican natives, overwinter the sections indoors. Keep them in a cool, dark place that gets no colder than about 50 degrees F. (10 C.).
Fall is the best time to divide tuberoses. Wait for the foliage to die back before you dig up the roots for division. You don’t have to divide them ever year, but don’t simply wait until you want to grow new plants. It’s best for the health of the tuberose plants if you dig up and divide the root systems every four to five years.
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5 techniques for 5 different bulb types
If an established bulb planting has begun to bloom sparsely, the cause is probably overcrowding—and that means it’s time to dig and divide.
You’ll also need to divide bulbs if you want to make more plantings of a favorite kind. Because each of the five bulb types increases in a different way, techniques for division differ as well.
To divide true bulbs, carefully break apart the parent and the increase (smaller bulb) at its base. To divide lily (Lilium) bulbs, remove outer scales from the basal plate, dip the ends in rooting hormone, and plant.
Corms renew themselves each growing season by producing a new corm and (sometimes) small cormels on top of the old corm. To divide, separate healthy new corms and any cormels from the old corms.
Tubers increase in size and in their number of growing points as they age, but most of them don’t form separate increases. To divide, cut a large tuber into two or more sections, making sure each has a growing point.
Rhizomes produce new plants from growth points along their sides. To divide, break the sections apart at the natural divisions between them be sure each division has at least one growing point.
Tuberous roots form multiple growing points. Some, like daylily (Hemerocallis), form separate plants that can be pulled apart this is usually done in summer or fall, when the plant is growing. Others, like dahlia, do not separate as easily. To divide the latter, cut clumps apart so that each root has a growth bud do the job before planting in early spring.
For fragrance and flowers in the garden you could look at a plant we commonly call Tuberose. The botanical name is Polianthes tuberosa, and they are commonly known simply by the common name of Tuberose. Popular as they are easy to grow, and do have great fragrance. The bulbs multiply readily and are very easy to divide.
Tuberose are a popular fragrant flowering bulb with fragrant white waxy flowers. Used initially in the perfume industry and now widely in the cut flower industry. The long lasting fragrance is a real attraction, even in the cut flower industry. Lovely white flowers around 2 – 3 cm long are often used in floral arrangements.
These are a warm climate bulb originally from Mexico and is a highly fragrant plant with masses of waxy white flowers on tall stems. Excellent as a cut flower and used for making perfume as well, yes it is that fragrant. These have been used in cultivation since the 1600s when they were first grown in the UK in Greenhouses, a real status symbol back in the day.
A sunny position is essential either in a container or in the garden. They flower late in summer so colder climates can be a problem. Tall growing to around .7m if you can grow them, and like perfumed plants, then this one for you.
Plant in spring and cover with around 4 – 5 cm of soil, water with a liquid seaweed fertilizer every week and try not to let dry out to much. Lift bulbs every 4 years and divide to promote better growth and increase the size of the clump. A little mulch in winter does wonders, so does good drainage.
Polianthes geminiflora is a separate species often difficult to find.
Tuberose plants grow from a rhizome, they will reach nearly 1m in full flower. Plant bulbs or rhizomes in late winter for summer and spring flowering. A humus rich but well drained soil in a sunny is essential. In colder climates these bulbs are lifted over winter, not sure this is needed in most areas of Australia
Best grown in warmer climates, they will grow well in cooler areas as long as they are well protected from frosts.
Tuberose bulbs flower and then form offsets, it is the offsets that you will digging and dividing.