Spring Tree Care: Mulching and Fertilizing

Thanks to Tom & Dawn for asking me the following question last week about their trees:
The Autumn Blaze Maple & Aristocrat Pear trees buds are appearing. Is it time to remulch and fertilize?

Well, yes. And maybe not, too! This wishy-washy answer really applies to everyone's trees as we head further into spring and are enjoying (finally!) some warmer weather. The fertilizer question is the easier part of this to answer: Sure, go ahead and apply your starter/root-stimulating fertilizer now on your new trees. New trees are those that have been in the ground for three years or less; starter fertilizer has a low nitrogen content and higher phosphorus for promoting root growth after transplanting. Tree roots will grow whenever the soil temperature is above 40F, so even early April would have been an ok time to put on the root stimulator. Nitrogen based fertilizers, on the other hand, should only be used for trees after a soil test indicates it's needed. If you want to have your soil tested, talk to the MSU Extension Office about how they can perform those tests for you.

Now for the mulch half of the question. There are a few variables here that need to be addressed. The first is - does the tree actually need more mulch? If the existing mulch has decomposed to 2" depth or less, the answer is yes. In that case, now we want to consider whether the soil is starting to dry out from all these massive rainfalls we've been having. Soils that are still pretty wet under the surface should probably wait a week or two before they get any new mulch. Damp or dry soils can definitely be treated with mulch now. What's best to use? Bark mulches - hardwood or red pine - for their acidifying and health promoting qualities are my favorites.

And here's a thought about adding to size of the mulch area - I like to increase the size of a mulch bed around evergreen trees every couple of years, to keep mowers away from the branches. Now is a good time to do that, again thinking about how wet the soil is below. You can use your favorite lawn-removal method: newspaper, roundup, or a shovel - and add up to 4" depth of fresh bark-based mulch. A one-foot strip around the perimeter of the tree does wonders for its branch safety!