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Encouraging your poinsettia to rebloom

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Poinsettia – Euphorbia pulcherrima 'Gutbier V-17 Angelika Red'
Photo: Jardin botanique de Montréal (Gilles Murray)
Euphorbia pulcherrima 'Gutbier V-17 Angelika Red'

How to get your poinsettia to rebloom

Caring for your poinsettia at home to coax it to rebloom is possible but will require special light conditions and sustained care. You’ll need to put it through a rigorous program if you want to get it flowering again in time for Christmas. Expect your plants to be less compact and spectacular than those produced in the greenhouse.

Give the plant a period of darkness

The poinsettia is a so-called short-day plant. In fall, the naturally shorter days initiate the formation of new flower buds and cause the bracts to become coloured. This phenomenon usually begins in mid-September, sometimes earlier for certain cultivars.

Often, in a home or an apartment, the naturally shorter daylength is not enough. To get a poinsettia to rebloom in time for the holiday season, it needs a period of total darkness every day.

From mid-September onward, give the plant a minimum of 14 consecutive hours of complete darkness every single day of the week, from 6 p.m. to 8 a.m., for eight to ten weeks or until the bracts start showing colour. Different cultivars may respond somewhat differently to this treatment.

Before starting this treatment, remove any weak stems, leaving only the best ones.

If the plant isn't given total darkness, the bracts may be malformed or the flower buds may drop off. Even stray light from outdoors can interfere with flower initiation.

Two tips to ensure total darkness for your plant:

  • Cover it with a cardboard box
  • Place it in a cupboard or a completely opaque room.

However, during the day, the plant needs bright light.

Temperature control and fertilization

While the flower buds are forming and the bracts changing color (mid-September to mid-November), it’s important to maintain a temperature of 20°C to stimulate the formation of good-sized bracts.

Once the bracts are fully colored, you can lower the temperature to 15-18°C to intensify the coloring.

Fertilize with an all-purpose fertilizer (NPK ratio: 1-1-1, such as 20-20-20) every two weeks. From November onwards, fertilizer with more potassium (NPK ratio: 1-1-2, such as 15-15-30) will stimulate flower formation. Following the darkness treatment, care for your plant as described on the page Caring for your poinsettia while in bloom.

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