From Humble Origins


A master gardener recently asked me how to germinate acorns because she had repeated failures. To be successful, collect the acorns soon after they have fallen from the tree. Never collect acorns that have caps still attached because those acorns are most likely empty. Only solid, firm acorns that have fallen from the tree without caps should be collected. A healthy, well-developed acorn is one that has separated from its cap while still attached to the tree.

After you have collected a few dozen acorns, float them in water. Those acorns that are firm and are most likely to germinate will sink to the bottom, while those acorns that are weak and possibly empty will float at the surface.

One out of four acorns has been attacked by insects and has an insect egg buried just inside its shell. The eggs will hatch soon after the acorns fall to the ground. To kill the egg without damaging the acorn, immerse them in a kettle of hot water with continuous agitation for at least 20 minutes. The water temperature should be 120 degrees, sufficient to kill any insect eggs without harming the acorns. Allowing the temperature to rise to 123 degrees or higher will kill the embryo of the acorns, and they will not germinate.

As soon as you finish heat-treating the acorns, sow them in rich garden soil, covering them with a mesh screen to prevent squirrels from digging them up. Acorns of the white oak species will sprout a root within a few weeks of being planted, but it will not sprout a stem until next spring; acorns of the red oak species will germinate in the spring, sprouting both roots and stem at the same time.

Acorns are generally planted one to two inches apart in rows and allowed to grow in place for two years before they are dug and transplanted into rows. Digging and transplanting oak saplings encourages the development of well branched roots.

When collecting acorns, keep only the largest and firmest acorns you can find. Research has shown that oak trees grown from large acorns grow faster and produce stouter stems during their early years of growth than oak trees grown from smaller acorns. This is important if you want your oak tree to develop a straight stem that will not have to be staked and tied. No one wants an oak tree with a crooked stem.


Discolored Azalea Leaves

Q Amidst this really dry period, some of our (relatively shaded) azaleas exhibit discoloration. They were watered about a week ago. Is this an ailment?

–Kent Mountford, Lusby


A The injury is possibly weed killer-related. The only nutrient-deficiency symptom that expresses itself like that is molybdimum, and I have seen that only once and then on poinsettia. Another possibility is that these azaleas are near a crushed blue-stone patio or walkway. Or was crushed bluestone used as a mulch? The injury could also be caused by nickel toxicity.