I have used these fertilizer spikes on some evergreens for three years. I have gotten at least 2 feet a year of growth. Frankly I have no idea if that is normal but my lawn guy was quite impressed with how well they did. We had a particularly cold winter here in
last year and many evergreens were "browned out". Mine were no exception but they have bounced
back beautifully. That was also
mentioned by my lawn guy that he has seen many that browned out but did not
come back very well. I used these in
spring and fall and they really seem to help.
I am not an arborist and this a purely anecdotal review.
If reviewing a product, it may have been received free of charge. That will NEVER have a bearing on my recommendations.