Volunteer Trees – Saving the Good Ones

When working in the landscape it’s common to find a surprising treasure – a healthy little tree. Usually, they were planted by squirrels or birds so aren’t in an ideal location, but it is possible to relocate and grow them into large shade trees. First, consider which seedling trees are worth saving.

Choosing the Right Trees - Good Guys vs. Bad Guys
Not all trees are equally beneficial to the landscape. Avoid saving trees with any of these qualities.

• Fast growers with soft wood or low aesthetic value, like silver maple (Acer saccharinum), mulberry (Morus spp.) or Siberian elm (Ulmus pumila).
• Invasive species – These trees easily spread by seed and can become invasive in low maintenance areas, crowding out native vegetation. This includes Amur maple (Acer ginnala), autumn olive (Elaeagnus umbellata), Callery pear (Pyrus calleryana) and European buckthorn (Rhamnus cathartica).
• Poorly adapted and non-native species including tree-of-heaven (Ailanthus altissima).

One great tree to consider saving? Any species of oak – they provide great value to landscapes and wildlife.

Transplanting
When it comes to moving trees, the smaller the better. Small seedling trees will reestablish on the new site quickly, if handled carefully and given good care. At a maximum, home gardeners should choose a tree with a trunk diameter of 2 inches or less to move.

Trees have the best chance of survival if moved when dormant – either in fall after leaf drop or early spring (March).

To protect the tree’s roots, you’ll dig a ball of soil and roots around the tree’s base and move it with as little disturbance to the root ball as possible. Make sure the soil is moist before beginning to dig to help the soil stick together; if necessary, irrigate the area 3-4 days beforehand.

To determine how big a root ball to dig, look first at tree height. If the tree is 4 feet or more tall, examine the trunk diameter at chest height. But remember, these are minimum guidelines. The bigger the root ball the better the tree will thrive after transplanting

Diameter at chest height (4 to 4.5 feet)

• 0.5 inches – minimum 12-inch diameter root ball
• 1 inch – minimum 16-inch diameter root ball
• 2 inches – minimum 24-inch diameter root ball

Trees less than 4 feet in height.

• 2 feet height – minimum 10-inch diameter root ball
• 3 feet height – minimum 12-inch diameter root ball

With a sharp spade, cut a trench 1.5 - 2 feet deep all around the tree. Place a tarp in the trench on one side of the ball and lean the tree toward the tarp so you can finish cutting the roots underneath. Once all the roots are cut, wrap the root ball in the tarp and move it to the new location. Don’t carry the tree by holding the trunk, instead grab the tarp or carry the ball. This minimizes soil falling away from the roots and doing damage to the small roots.

Ideally, the tree should be replanted immediately in its new location. Dig a planting hole 2 - 3 times as wide and slightly shallower than the root ball you dug. Once the planting hole is ready, set the tree in place, position it as desired, then gently remove the tarp. Be very careful with the root ball and prevent it from breaking apart. Back fill the planting hole with soil and gently firm it around the root ball. Don’t firm the soil with your feet! Pressing with your hands and removing air pockets with water are best.

Planting Your Own “Volunteer” Tree
Want to avoid the whole “digging and moving” process? It’s easy to plant oaks from seed and is a fun activity for children or grandchildren.

Start by finding an oak tree producing acorns. There are two large groups of oak species in Nebraska – white or red oak. Look at the tree’s leaves to determine which it is.

• White oaks – rounded leaf edges
• Red oaks – pointy leaf edges

Collect Acorns – Don't pick acorns still in the tree. These are immature and may not grow properly. Wait until they fall to the ground. For every tree you want to grow, collect 4 or 5 acorns. Discard any acorns with damage or holes, or which still have their cap attached. Drop the acorns in water and discard any that float.

Plant Acorns – Find a location for your new tree, ideally one with full sun and well-drained soil. Dig up the soil to loosen it. Plant the acorns about 3-4 inches apart and 1 inch deep; cap side up, pointy end down. Water the seeds thoroughly.

Protect the seeds from being eaten by wildlife by creating a tube of chicken wire mesh, at least 24 inches tall. Place it around the planting bed and bury the bottom edge in the soil or use landscape staples to anchor it to the soil. The top edges can be bent inward and secured to create a “lid”.

Your seedlings will emerge in either fall (white oaks) or spring (red oaks). They will not all emerge at once, but a few at a time over 1-2 weeks. If conditions get dry, water the seedlings each week so they don’t dry out. Once they have all emerged, decide which to keep and remove all the rest.

After planting Tree Care
Good care for newly planted trees is also critical for the tree's success. For complete instructions on post-planting care, refer to Nebraska Forest Service's publication, "Care of Newly Planted Trees"

Next week, we'll discuss how to handle those volunteer trees you don't want.

Images

1. Young oak seedling. Image by Brian Lockhart, USDA Forest Service, Bugwood.org.
2. White oak, Quercus alba, leaf. Trees in this group have rounded leaf edges. Image by Paul Bolstad, University of Minnesota, Bugwood.org.
3. Northern red oak, Quercus rubra, leaf. Trees in this group have pointed leaf edges. Image by Paul Wray, Iowa State University, Bugwood.org.