To plant my new tree, is top-dressing with Leafgro better than mixing it into the soil?

Asked October 24, 2019, 4:15 PM EDT

Hello. We are planting American Elms and Redbuds, and have read that it is no longer advisable to mix the soil amendment (such as Leafgro) into the soil in the planting hole, but rather it is better to top-dress. Do you agree? If we top-dress, how deep should the Leafgro be? and then should we mulch with wood chips and if so how deep? Thank you.

Baltimore County Maryland

1 Response

You can add some organic soil amendments to backfill when you are planting, but the backfill should be predominantly the same as surrounding soil. this allows the roots to move more easily into the surrounding soil.

A generous hole allows room for roots from the rootball to move outward. Some organic material is helpful, but what you're aiming to avoid is the "bathtub effect" which is a hole full of organic matter in a clay soil. When it rains, the hole quickly fills with water and cannot drain out quickly into clay. Thus it sits there and can drown a tree.

Top dressing with organic matter is always great. It serves many purposes--mulch, breaking down into nutrients to feed the plant, and improving soil structure (very very slowly.)

You can use bark mulch as soon as you plant. Two important rules: Never pile mulch on the base of the plant--keep it back a few inches. And, do not mulch too deeply--2-3" is good.