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How to make a Poinsettia Bloom (or Re-Bloom)

How to make a Poinsettia Bloom (or Re-Bloom)

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The poinsettia plant is better known as the Christmas Star. The flowers are barely noticeable. The leaves though, they’re the star attraction (I couldn’t resist the pun).

Poinsettia is native to Mexico so think super warm areas to keep this plant alive. However, given that it only needs warm temperatures, and that it’s even resistant to direct heat, (meaning it can tolerate being parked near a radiator), indoor growers have a fairly easy time with this.

What doesn’t come easily is getting it to bloom, or rebloom, whichever the case may be.

The most popular color choice for poinsettia is the signature red. Sales for this skyrocket near Christmas as it’s the one with the bright red leaves (bracts) in the shape of a star, with the yellow flower buds in the center. Very Christmassy!

When you buy a poinsettia at the end of the year, it’ll already be in bloom. The colors last until after the holidays, which is why this is nicknamed the Holiday Plant. After the holidays, it will lose its color. It’s just the type of plant breed it is. It’s been bred to bloom later in the year when the days get shorter.

Also note that by bloom, it’s referring to the color of the leaves, and since those are modified leaves, they’re called bracts.

Poinsettia plants are grown for their colorful bracts, not their teeny flowers. But, don’t disregard those because they’re a great indicator of when a poinsettia’s about to put on a burst of color. When the flower buds in the center are tightly closed is the post-color phase.

The shorter the days get, the more this plant blooms. But, only if they’ve had around 8-weeks of darkness with some decent sunlight, and if you’re reblooming last year’s poinsettia plants, you’ll need to have taken care of them throughout the year. Not just the eight-week period before they bloom.

Universal Care Instructions for Poinsettia Plants

  • Keep them in temperatures consistently between 60oF to 70oF (15.5oC to 21.1oC).
    • 50oF (10oC) is the danger zone. Below that can kill these plants.
  • It’s recommended to let the top inch of soil dry out before adding water. Then, when you do, only add a little.
  • Keep them away from drafts, so don’t have these near doorways, windows that are frequently opened, or close to open fireplaces.

The above are best plant care practices for indoor poinsettia plants that are actively growing or in bloom. To get them to rebloom, that’s trickier.

How to Make Poinsettia Plants Bloom (or Re-Bloom)

Getting your poinsettia to re-bloom in its second year can get you a better-looking bushier plant than the original one you bought.

The trick to making a poinsettia fill out more is, like a lot of plants, pruning and pinching.

Each stem on a poinsettia grows best with just two nodes. They’re the tiny bumps on the main stem.

You don’t want to do your pruning when the leaves are yellowing, usually January or around mid-February – it seems long for a winter flowering plant but there are new breeds that can stay in color for a few months at a time rather than the 4 to 6 weeks bloom period that traditional poinsettia usually have.

The trick is to know when to leave it be. When you start seeing the leaves lose color, cut back on watering it. Some say to cut away dead leaves, but truth be told, dead leaves will fall off anyway.

Let the leaves go brown. It sounds ill-advised, but you’re avoiding stressing it at a time that it’s likely not got a lot of energy.

Ease up on watering, keep the temperatures indoors stable (60oF to 70oF) and put it somewhere dry and dark.

Once the leaves are yellowing, only water it enough to keep the stems from wilting. Let the bracts turn brown then fall off naturally.

Pinching and Pruning Begins in April

After a couple of months of really light watering and storing in the dark, by April, all the bracts should be off the plant leaving only the stems. If you’ve watered it right, those stems should be healthy, bare, and standing upright.

Now for the sad part… cut them back. Prune the stems back to four to six inches above the soil line.

Give them warmth and plenty of sunlight to encourage new growth. Once you see early growth, start feeding it a diluted balanced fertilizer starting at a monthly frequency, up until the summer months.

By summer, or when there’s absolutely no chance of night temperatures dropping below 50oF, move your plant outdoors to soak up more sunshine. Just make sure it has some shade from the hottest afternoon sun.

When poinsettias are actively growing, they need over 12 hours sunlight daily. The more sun they get, the better.

In the summer is also when to up the ante with fertilizer, applying it at a weekly rate. The watering stays the same though, waiting until the top inch of the soil is dry. Poinsettia are prone to root and stem rot, which is why the soil needs to dry out between watering.

As new growth comes through, pinch them back to encourage bushy growth.

Poinsettias can grow to be over ten feet tall. As a houseplant, or the small ornamental Christmas Star plant we try to grow for the holiday season, you don’t want them growing upwards. You’ll want them to put out sideshoots so that they spill colorful leaves around the pot, something that only happens when you train it to do that.


Train Your Plant by Pinching

Pinching stems encourages new growth to emerge. On Poinsettia plants, the active growing season is the summer. Pinching should be done up until August to get the plant to put out the most growth. These grow in the summer, then bloom in the winter.

Pinch the tips of new growth above the second growth node. Leave two nodes on the stem and anything above that, pinch it off.

You can do this with sterile pruners, or just use your thumb and forefinger. The stems aren’t thick. They do contain toxins though so you’ll probably want to wear a pair of gloves when handling your poinsettia plant.

Prepping Poinsettia Plants for Blooming

By late August, going into September, bring your plant indoors. Do this earlier if there’s a chance of temperatures dropping below 50oF. In most areas, that’s around September. At this point, bring your plant indoors and start preparing it for blooming.

Poinsettia plants go into bloom when the days get shorter. So, 12-hours of light and 12-hours of dark isn’t going to cut it.

Reduce their daylight to 10 hours and for the other 14 hours, leave them in complete darkness undisturbed. The slightest of light will impede their potential to bloom.

If you like, go with an 8-hour light cycle to give them 16-hours of total darkness. Keep in mind though, this is done daily, and for 8-weeks, so if you prefer it, go with 10 or 11-hours.

The simplest way to keep your plant in complete darkness is to put it under a cardboard box with the lips weighted on all sides so that no light can reach it.

The dark and light cycle needs to be done daily for up to eight weeks. You’ll start to see color come through after a couple of weeks, but give it up to eight weeks to keep it blooming for longer.

Given the habit training poinsettia plants need to bloom, it’d be wise to use reminders on your phone, or even use the alarm function.