How to Get a Hoya to Flower, and Never Cut the Spur Off

The spur is permanent, the flowers are not

Hoya flowers hang from a short woody stub that grows out of the stem. That stub, the peduncle, is not part of the flower head. It stays on the plant after the flowers drop and it produces the next umbel, and the one after that, from exactly the same point for years on end.

This is the single most important thing to know about the plant, because everything about a spent hoya flower head invites you to tidy it away. The flowers go brown, they drop, and what is left is an ugly bare stub two inches (5 cm) long that looks dead. It is not dead. Cut it and you have thrown away the only place on that stem where flowers were going to appear.

If you have already cut the spurs off, the plant is not ruined. It will make new ones on new growth. But you have lost a year at least, and on an old spur that had built up to a dozen flowers you have lost more than that.

It flowers on mature growth, so it has to be old enough

A hoya raised from a cutting usually needs two to three years before it flowers at all, and often longer. There is nothing you can do to a young plant to bring that forward. Feeding it harder produces leaves, not flowers.

Flowering also depends on the plant having length. Hoyas are climbers, and the spurs form on growth that has run on and hardened rather than on the soft new tips. A plant kept short by constant trimming can grow well for a decade and never flower, because you keep removing the wood that would have carried the spurs.

1. Let the long bare runners grow A hoya throws out long leafless tendrils that look like a mistake. They are how it climbs, and they leaf up later. Cutting them off is the second most common reason a healthy hoya never flowers.
2. Give it something to climb or trail from Train the runners onto a hoop, a trellis or a length of wire, or hang the pot so they can fall. Either works. What matters is that the growth is allowed to extend and mature.
3. Do not keep repotting it A hoya flowers best when the roots are crowded. Moving it into a larger pot every year pushes it into leaf growth and delays flowering by a season each time.

What actually triggers a flush

Once the plant is mature, four things decide whether it flowers: light, a cool and dry spell over winter, being pot bound, and being left alone. The first two do most of the work.

Record the week you first see a bud cluster forming, and against it note where the plant was standing and how cold the room got the previous winter. Two years of that and you will know exactly what your plant responds to.

Buds that form and then drop

Bud drop, where a tiny cluster of pinheads forms and then falls off before opening, is the frustration everyone hits. It has a small number of causes and they are all things you did.

1. You moved it A hoya in bud should not be moved, turned or repotted. Changing the angle of the light is enough to make it drop the lot. Decide where it lives before the buds appear, and then leave it there.
2. It dried out completely Developing buds are the first thing sacrificed when the plant runs short of water. Through the bud period, water a little sooner than you normally would rather than letting it go bone dry.
3. It got too much water The opposite error does the same thing. Compost kept wet while the buds develop causes the cluster to yellow at the base and drop off in one piece.
4. The room got cold or drafty A sudden drop of fifteen degrees overnight, or a door opening onto a cold hall, will do it. Buds need steadier conditions than leaves do.

While it is in flower, and afterwards

The umbels open over a few days and last one to two weeks. Most hoyas are strongly scented in the evening, and many drip nectar, which is sticky and will mark a floor, a windowsill or the leaves below.

Do not spray the open flowers with water and do not wipe the nectar off the umbel itself. When the flowers are finished they drop on their own. Sweep up what falls, wipe the nectar off the floor and the leaves below, and leave the spur exactly where it is.

Many hoyas flower two or three times in a season from the same spurs, so a plant that has just finished may well be building the next cluster within a month.