NATIVE TREES AND PLANTS

COMPANION PLANTING

All plants thrive in communities and suffer in isolation. Both soil and root health is directly dependent on the plant life that covers and fills the top layers of soil. Especially for a newly planted street tree, planting the entire tree box, instead of just using mulch, is likely to significantly impact the health and longevity of that tree, decrease the need for watering and eliminate the need for fertilization.  

Most longer-lived tree species, like Oak or Maple, actually grow stronger branches and are overall more healthy when, if in their early years, they grow in the shade of other trees. In city conditions, this is difficult to reproduce, but it opens the possibility to planting slower growing, longer lived trees as smaller, younger plants alongside a faster growing, shorter lived species in the same tree well. By the time the shorter lived species is ending its life, the longer lived tree will be ready to take over and thrive. The intermingling of the roots of those trees will benefit both, and the dead roots of the shorter lived tree that are left in the ground once that tree is taken down will create a more natural and healthier soil that will benefit the older growing tree far into the future. Equally significant is the ability to plant smaller, younger trees for the longer lived species, and using the shorter lived species to protect them for the first few years. Younger plants are far better at adapting to the new conditions of a transplant—their roots are ready to grow, whereas an older tree that is transplanted has just had its roots removed and will never fully recover from that trauma. Even if that tree survives transplanting, its longevity is significantly compromised—it will never grow to be the 100-year old tree it is genetically capable of becoming. Ideally, long-lived trees should be planted with no more that 1” caliper (stem diameter). Planting young trees also saves costs in both production and transportation, as well as in maintenance, as they will require less from us once they are planted (large trees will always require supplemental watering for the first 2-3 yrs.).  

Covering the ground around the tree with native grasses, sedges, ground covers, and wildflowers instead of bark mulch would also greatly benefit the young tree newly planted and create additional habitat for pollinators and other native insects. Plants direct rain water with their leaves and roots into the soil and then hold it there. Mulch, especially when walked on, acts more like an umbrella, shedding water rather than absorbing. Plus, by design, mulch decreases the life in the soil—it keeps weeds down, for a while, but also decreases the microbial life that would be living among the roots of those plants. It is that microbial life that is so important to the health of the tree planted there, and so mulching with bark mulch instead of plants is counterproductive.