Question
I recently re-potted a poinsettia of mine, using a bag of old
potting soil that had been left out in the shed most of the
summer. After re-potting and bringing it back inside, I've
started to notice these super tiny little black
larvae/worms/creeping bugs (like pen-dot size, really tiny and
thin) on the shelf around the pot, seeming to congregate in any
little splashes of water from watering. I haven't had these
before now, so I think they must have been in the soil I used.
If you could please let me know what they are and how I get rid
of them, I'd be most appreciative. Also, any tips on "re-
blooming" the poinsettia would be helpful. I've had it almost
three years now and haven't been able to get it to change color
again since that first Christmas.

Thanks so much!

Answer
Jen,

The soil you used has a lot of peat moss and it attracts fungus gnats if you leave water in the drain tray or water it excessively. It holds a lot of water and if water is left in the drain tray or if you water every other day the fine roots of plants begin to rot and that attracts the fungus gnats which are just like fruit flies being attracted to rotting bananas. You need to empty the drain tray an hour after  watering the plant and do not water it again until the plant feels light weight and the soil surface has felt dry for 4 days.  

As for getting it to rebloom you must follow the following instructions explicitly:
June: More the poinsettia outside, pot and all. Keep it in a partially shaded location and maintain your watering and fertilizing schedule.

July: In early July, pinch back each stem by about one inch. This is to encourage a stout, well branched plant. If left unpinched, the poinsettia will grow tall and spindly.

August: By mid-August, the stems should have branched and leafed out. Once again, pinch or cut the new stems, leaving 3-4 leaves on each shoot. Bring the plant back indoors and back into your brightest window. Continue watering and fertilizing.

September: Continue regular watering and fertilizing. Make sure the temperature stays above 65 degrees F.

October Poinsettias are short-day plants, meaning their bud set is affected by the length of daylight. To re-bloom, poinsettias need about 10 weeks with 12 hours or less of sunlight per day. You will have to artificially create these conditions and it抯 crucial that you be diligent.

Beginning October 1st, keep your plant in complete darkness from 5 pm to 8 am. Any exposure to light will delay blooming. Use an opaque box or material to block out light. Many people place their plants in a closest, but if light gets in though the cracks or if you open and use the closet, it will affect the bud set.

Move the plant back to the sunny window during the daytime and continue watering and fertilizing.

November: Around the last week of November, you can stop the darkness treatment and allow the plant to remain in the window. You should see flower buds at this point

December - Stop fertilizing about December 15th. Keep watering and treat your plant the way you did when you first brought it home in bloom. If all has gone well, it should be back in bloom and ready to begin the process all over again. What about poinsettias being poisonous?

If you have more questionss feel free to write again. Good luck.

Darlene