Proper tree selection and appropriate site preparation are essential to the success of new trees in the garden. In spring, searching for new trees can be fun yet overwhelming. With so much new stock at the nursery, it can be difficult to decide what to buy. A quick site analysis of your garden’s conditions (soil, sun/shade, wind exposure) will help narrow your options. To be sure your investment in new trees pays off, take the time to prepare the site, condition the soil and nurture them.
Before you plant your new trees, find out the composition and pH level of your soil. Soil test kits are readily available at most greenhouse and nurseries. With some exceptions, most plants will thrive when the pH level is somewhere between 5.8 and 6.5. It’s difficult for plants to get the nutrients they need if the level is too high or too low. To adjust a pH level which is too high, meaning the soil is alkaline, add aluminum sulfate. If the soil is acidic and the pH level too low adding lime will create more favorable planting conditions.
Soil composition is also an important factor when planting trees. Most trees don’t thrive in soils which are too sandy and dry or in poorly drained clay soil. While wetland trees, such as red maple, can tolerate some standing water, most trees cannot. For poorly drained clay soils, adding composted bark or other course textured organic material will improve drainage. Be sure the finish grade of your garden slopes away from the planting beds and avoid low spots as water may not drain for several days.
When planting a single tree in extremely poorly drained or compacted soil, set it about 2” to 4” higher than its original planting depth and build the soil up to the base of its trunk. This will allow oxygen to reach the tree’s roots and prevent water from collecting beneath it‘s roots. The top of the root ball may dry out quickly in the summer, so be prepared to water frequently during hot weather.
Sandy soils drain too quickly, don’t provide many nutrients well and often dry out quickly. As a result, sandy soil requires the addition of organic matter such as manure, compost and peat moss in order to help the soil retain water. When adding your soil conditioners, steer clear of wood chips as they tend to rob plants of nitrogen. Use well composted organic products with a rich, earthy smell and a crumbly, dark brown appearance.
Once you have the proper soil conditioners you’re ready to plant. Dig a hole at least twice the diameter of the root ball and just as deep. It’s important to be sure that the top of the root ball meets the existing grade of the garden (planting new trees below the top of the rootball may cause premature plant decline). The wider the hole the easier it will be for new roots to grow and spread. Once you’ve reached the correct depth, place the tree in the hole. If the tree comes balled in burlap, remove the nylon twine and pull the burlap away from the trunk of the tree and tuck it down beside the rootball. Burlap is biodegradable so there's no need to remove the burlap completely; removing it can sometimes cause the soil to fall from the roots.
Container grown trees are planted the same way that balled and burlaped trees are. Before removing the plant from the container check the bottom of the container; roots often will begin growing out of the drainage holes, if they are cut them. If the plant has become root bound loosen the roots before planting.
Next, backfill around the rootball with a mix of existing soil and appropriate soil conditioners. At about halfway, tamp the soil down lightly to prevent air pockets from forming, water and let the soil settle. Finish backfilling, construct a saucer around the trunk of the tree and water again. Staking may be necessary if the plant is tall or exposed to wind.
Applying 2 to 3 inches of bark mulch around the trunk of the tree will help prevent weeds from growing, increase the soil’s water retention and will eventually break down adding organic material to the soil.
Planting trees in the spring gives them an entire growing season establish themselves in the garden. Hot dry weather can stress newly planted trees so monitor them and irrigate as needed. In general, trees are very low maintenance and with proper site preparation they can last generations.