Poinsettia and Lemon Tree


1. I purchased a Poinsettia this past Christmas and would like to maintain it for this coming year. Advise if I should repot, fertilizing tips, lighting required.

2. I purchased a Lemon Tree last summer. It has done quite nicely through the Winter. Should I repot, fertilizing tips.

3. We have these small bug flies around our plants and flowers, how can we remedy this issue.

Thank you


Thank you for submitting your questions to the Toronto Master Gardeners.  I will address each one in order.


It can be a challenge to coax a Poinsettia to rebloom but not impossible.  Poinsettias are photoperiod (also called “short day”) plants, meaning they have specific light requirements in order to bloom.  If you haven’t done so already, cut the stems back to about 8” (20 cm).  Continue to water the plant and use a good, balanced all-purpose fertilizer every 2-3 weeks.

You can gradually move your poinsettia outdoors (increase outdoor time by a couple of hours each day once the risk of any frost has passed) into a shaded, but not too shady location.  Poinsettias need sun but not a lot of direct sun.  Keep the plant well-watered and prune back the stems as needed to keep it bushy.

You should move the poinsettia indoors again in early to mid-September.  Continue to keep it well-watered and fertilized.  The next three months will be critical in terms of the plant’s lighting requirements.  If these conditions are not met, the coloured bracts (modified leaves) will not develop. Your poinsettia will need 6-8 hours of bright sunlight and temperatures between 15-20C (60-70F) each day and 14 hours of complete darkness overnight.  This can be achieved by putting a light-proof box over the plant or moving it into a cupboard nightly – be sure to block up any crack under a cupboard door.  Continue this routine for 10-13 weeks and the coloured leaves should develop for the Holiday period in December. The importance of total nighttime darkness for 14 hours cannot be overemphasized in order to have success.

Whether or not you need to re-pot your poinsettia depends on its current condition. Signs of a pot-bound plant can include:

  • Roots growing out of the bottom of the pot
  • Cracks in the pot
  • White crust of salt on the soil surface
  • Need for more frequent watering

Your new container should be at least 2 inches in diameter larger than the old one and have drainage holes in the bottom.  Fill the new container with about 1 inch of good quality potting soil.  Gently extract your plant and place it in the new pot. Fill the space around the root ball with soil and water the plant to help ensure there are no air pockets. Add more soil as needed.

You may also be interested in the Royal Horticultural Society Poinsettia information page.


Lemon Tree

You can use the guidelines mentioned above to help decide whether or not your lemon tree needs to be repotted.  If you decide to repot, a wider rather than taller pot is advised as long as there is sufficient depth for the root ball.  Use good quality potting soil.  During the growing season (spring through fall), you can lightly fertilize monthly with a higher nitrogen fertilizer (for example 3:1:1).  Avoid over-fertilizing: less is better.

Insect Pests

There are a few possibilities regarding the small “bug /flies” you are seeing round your plants.  Identification of an insect pest will be easier if you are able to note the size, colour and any other characteristics of these bugs.  It is also helpful to know what, if any, damage they are causing to your plants (e.g., leaf damage, honey-like residue on plants, etc.).  Please feel free to submit additional information and send a picture to us, and we will try to help with the specific identification.

Insect pest prevention includes ensuring your plants have optimal growing conditions with the correct amount of light, water, soil and good air circulation.  Check new plants or plants that you bring indoors for pests before introducing them to your home.  Cut flowers can be a source of pests as well.