Question
I have a Sultan plum tree planted 2 yrs ago. It has not been vigorous, and now has pinkish leaves and little new growth at the end of our summer. It had a dozen good plums this season, picked about 2 weeks ago. it is in sandy/silty soil, very good drainage, but maybe short of some nutrients?? Can you help me please??

Answer
Hi Murray,

It is possible that your tree could use a little fertilizer, but it would helpful to determine exactly what it needs.  You may want to have the soil tested for nutrients.  There are many soil testing labs and I simply searched on the internet for "New Zealand soil testing" and found several.  You send the company soil from under the plum tree and they will help determine what you need to add.  In general, I prefer to fertilize trees in late winter or early spring, right when the buds start to swell.  But, if the trees are extremely deficient, it may be helpful to split the fertilizer application and apply some now and some at the beginning of the next growing season.

If you choose not to have the soil test, you will have to guess what the trees need.  It is best to use a balanced fertilizer such as a 10-10-10.  These numbers refer to the amount of nitrogen-phosphorus-potassium in the fertilizer.  I would recommend a fertilizer for trees and shrubs because these are often granular and can be sprinkled under the tree.  They will slowly release in the soil during rain events.  

Good luck with your trees!
--Jen