They are very light-sensitive for blooming. If someone added an outdoor light, it can be enough to decreas ebloom set.

Also, they are short-lived perennials, so they might be wearing out.

Fertilizer? Any one meant for shrubbery would do.

Short-lived perennials? There are poinsettias in my neighborhood that are more than 15 years old. You could well be right about the light, lazygardens, but that wouldn't affect the growth or health of the bushes.

If your whole garden is getting weak this year, alba gardener, the first thing I would check is the water source--changing from a pure well to salty river water, or vice-versa, can make a big difference. Also, a water softener can make a big difference, too, if your irrigation system (or hose) is connected to it. Potassium water softeners will have the same effect, in time.

Another possibility is phosphate overload. The alkiline soils prevalent in the Southwest hold phosphate ions very well. Consistent use of high phosphate fertilizers--such as Super Bloomer, Bloom Booster, or even the old formula of Miracle-Gro (15-30-15)--can cause stunting and/or chlorosis, over time. The cure is to leach once or twice, preferably with humates to "chelate" the extra phosphates and make them more soluble, and use only low-, or no-phosphate ferilizers for a while.

Hope this helps,
Kevin : )

Thanks Lazygardens,for your reply to my question regarding the pointsettias.
Kevin, thanks for your information too. These poinsettia shrubs have been in the garden for many years. This house was built in 1939, and we bought it from the original owner after he passed. These shrubs have pretty thick trunks which leads me to believe that their old. I would like to keep them healthy as they are beautiful when they're in bloom during the holidays.
alba in Ca

Look for changes:
Different water source.
Institution of chlorination and/or floridation of water supply--usually not a problem, but sometimes the first few months or years of a program can be a little overzealous.
Re-landscaping, root pruning by trenching machine, change of grade, extension of pavement, washing of cement mixers, etc.
Change of watering system or schedule.
New "mow & blow" guys, especially if they offer extermination, weed control, or fertilization services--sometimes the worst garden pests are those "helping" us!
Unusual weed control on the part of your neighbors--some "weed controls" are actually soil sterilants, some of which travel up to several hundred feet in the soil, with rain, and persist for years, without treatment.
Here in Arizona, long term drought has changed the chemical nature of our water supplies, making them more alkaline and higher in sodium, and making acidification and salt control more critical.
Urban heat island effects and, possibly, global warming, have caused night temperatures to rise over the last decade, and I know that Poinsettias are one of the more sensitive species to heat damage. Heat mitigation techniques, such as mulching and soil aeration, now become necessary in some climates, and more critical in others.

Sometimes the most absurd changes, such as a broken water timer, or an inventively lazy teenager, can have profound effects on plant growth.

Good luck!
Kevin