Small Acorns Produce Great Oaks
Nov. 1, 2017 at 9:21 a.m.
We are fortunate in East Texas to have many native species of deciduous and evergreen oaks which make excellent landscape trees. However, many of these species cannot always be purchased in retail garden centers since they are not commercially propagated. So, if you see a native oak you would like to have in your landscape, the only way of getting one would be to dig the native tree, which is often impossible or to grow one from an acorn.
There are many benefits which can be gained by selecting acorns from the most desirable trees native to our particular area. Characteristics worth noting when choosing a mature tree for a seed source are desirability of leaf color and shape, drought tolerance, absence of galls, trunk form, vigor and umbrella-shaped canopies. However, you should realize that oaks are wind-pollinated. This means you know one parent but not the other. The undetermined pollen source in the formation of the acorn may dilute the desirable characteristics sought.
Collect acorns in the fall of the year from October to December. It is not uncommon for the white oak group acorns to germinate while on the trees. Ripe acorns can be picked off the tree before they fall; often it is wise to do so in order to escape weevils which attack those acorns that fall to the ground.
Physiologically, mature acorns are brown in color while those which are yellowish are not ripe. As a rule of thumb, a mature corn will snap cleanly from its cup without leaving a tissue residue. To ensure success with your acorns, use the "sinkers" test. Place the acorns in water and discard acorns that float in the water along with those that show pin-sized weevil exit holes.
Fall seeding of oaks is preferable to spring seeding. The white oaks have little to no dormancy and will germinate as soon as they mature in the fall, while the black oak group needs a 1 to 3 month chilling treatment in soil before they will germinate in the spring. Therefore, by planting the acorns in the fall the acorns will germinate when they need to, and it will take all the guesswork out of which groups your selected group belongs to. Since acorns of most species lose their viability when stored, you will also avoid that potential problem. As little as 15 percent moisture loss can reduce viability by 96 percent. This is why acorns that have been lying on the ground for two days may not germinate.
Ideally, acorns should be planted immediately after collection. Acorns can be planted in shrub beds and moved after one year of growth or seeded directly in the area you would like the tree to grow. Prepare the soil by adding organic matter before planting. Plant the acorns one to two inches deep.
Organic mulch such as peat moss or compost applied to the seedbed will conserve moisture, protect against soil crusting, weeds, rodents and cold temperatures.
Blue jays, crows and squirrels have an uncanny ability to find planted acorns so it may be helpful to cover the area with hardware cloth until they start to germinate.