Question: We planted this knife acacia about eight years ago. It remains spindly and hasnβt grown as fast or lush as the previous one. (I think it succumbed to a three-day hard freeze a few years back and went to plant heaven). Do you believe it needs more/less water or should we start over? I dislike giving up on a plant that may thrive with some changes. Itβs on a drip currently watering three times a week for 30 minutes, less in colder months
Answer:Β Your acacia might have been damaged by a frost a while ago but I see no remaining damage and this species (Acacia cultriformis, aka knife-leaf wattle) is supposed to be frost tolerant. Mostly it appears to be lacking nitrogen and/or receiving too much water according to the yellowing leaves. Actually, theyβre not really leaves but rather leaf-like flattened stems called phyllodes. Since it is a plant that typically does well in arid regions, you should switch to irrigating it more deeply and less frequently. I think once every three weeks to a depth of 24 inches would be better than your current schedule. You could also apply a slow-release fertilizer to the surface around the root zone that can be watered in over time. I agree with your idea of not giving up on this plant. Itβs a very nice one and worth another effort.
Peter L. Warren is the Forest Health Program coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
