Answer: It's usually best to wait until new growth begins in the spring before applying fertilizer. Since you're promoting lush, green, vegetative growth in your boxwood, choose a balanced fertilizer such as 10-10-10 or 20-20-20 and apply in amounts recommended on the label. You want flowers to develop on your bougainvillea so you'll want less nitrogen (the first number on the fertilizer label) and more phosphorous and potassium (the second and third numbers on the label). Phosphorus promotes flowering. For the bougainvillea, choose a 10-20-20, or similar formula with less nitrogen than phosphorous and potassium.
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