By C.J. Walke
As the days grow longer and the sun climbs higher, we are slowly rolling into the month of March, and it’s time to prune your fruit trees and maintain the structural framework that will support bushels of beautiful, organically grown fruit. Remember to keep your tools sharp and your cuts clean, and a healthy tree will heal its wounds and respond with growth that improves fruit quality and overall tree vigor. (For a full write-up on pruning, see The MOF&G, Dec.-Feb. 2011.) Once pruning is finished and March slips into April, dust off the shovel, fill your wheelbarrow with compost and mulch, and head to the orchard to plant a few more fruit trees.
Planting Young Trees
Ideally you prepared for your new trees by tilling, cover cropping and amending the soil during the last growing season, but an impulsive green thumb has a hard time passing by a young plant in need of an earthy home. I understand. However, a year of soil preparation is extremely valuable for getting young trees established and off to a solid start.
A soil test, the first step in the process, determines how to adjust your soil pH, what your nutrient levels are and which amendments are needed for balanced tree growth. (Of course the amendments should be approved by OMRI – the Organic Materials Review Institute.) Then you can till or dig the future tree locations, mix in aged compost and needed amendments, and cover crop or heavily mulch to keep out weeds and continue to build the soil.
Whether young trees are potted or bare-root will determine the best way to dig the hole and set the young tree. For a potted tree, the hole should be as deep as the height of the rootball, so that when you back-fill the hole, the top of the soil just covers the top of the rootball. The base of the hole should be firm, so that the tree doesn’t sink as it and the soil settle.
Plant a bare-root tree at roughly the same depth that it was planted in the nursery. This may be hard to determine, but usually the color changes where bark tissue transitions into root tissue. Most fruit trees tend to have darker bark tissue than root tissue, and often the root tissue has a slightly orange-ish color. I like to loosen the soil at the base of the hole, build a small mound to set the bare taproot into and gently lay the lateral roots outward while carefully backfilling. Handle these young roots gently and don’t tamp the soil aggressively.
Planting too deep can “choke” the tree by burying bark tissue that should be exposed to the air; it can also disrupt the flow of nutrients from the root system up through the rest of the tree.
Plant dwarf and semi-dwarf trees with the graft union about 2 inches above the soil; with deeper planting, the wood above the graft may send out roots, turning your dwarf tree into a full-size standard tree.
Shallow planting can expose roots to excess air, even when they’re right under the surface of the soil, causing them to dry out quickly and eventually die.
Mulch to Suppress Weeds and Build Soil
Once the tree is in the ground, I like to build a small berm of soil around the perimeter where disturbed soil meets the undisturbed, roughly 3 feet in diameter, to help retain and concentrate water on the young root system. I also like to mound aged wood chips or mulch hay over this berm to help retain soil moisture while suppressing sod and weed growth. Since we typically plant trees in fields or other open spaces, suppressing sod so that it does not compete with tree roots will give the tree a great jump on life.
Keeping weeds out of the bare soil in the planting zone, inside the berm, is also crucial for reducing competition and can easily be done by lightly scratching the ground with a hoe every week or two.
Mulching is also a great way to build the soil around trees, as well as other perennial crops, since disturbing the soil can damage roots or even kill a young tree. Aged hardwood chips, also called ramial chips, effectively recycle nutrients into the soil and provide the necessary conditions for beneficial mycorrhizal fungi to thrive. In the MOFGA orchards, I typically mulch with hay for the first year to suppress weeds and build soil, then bring in ramial wood chips.
Getting your trees off to a good start in the early years will help ensure healthy and fruitful trees for years to come.
C.J. Walke is MOFGA’s development associate, librarian and organic orchardist. You can address your orcharding questions to him at 568-4142 or [email protected].