If you have a dog, you should be extra diligent these days about examining its fur for ticks. My wife, who works next to a park resplendent with mature oak trees, brought attention to the fact that there are few if any acorns around this year. Fewer acorns mean fewer field mice, the preferred hosts for ticks and, in the absence of field mice, other hosts such as dogs and even people need to be on the look out for hungry ticks, which transmit Lyme disease.
Mystery surrounds the infrequency of acorn production. Oak trees produce heavy acorn crops every two to seven years. Years of banner crops are referred to as mast years, with off years seeing drastic decline in acorn production, all the way down to zero acorns. One popular theory holds that oak trees have an uncanny ability to sense the presence of acorn predators — squirrels, gophers and, especially, field mice. Oak trees “understand” that continual heavy acorn production in a succession of mast years would be accompanied by an explosion of predator populations. Rodent predators devour acorns before they can develop into seedling trees. Thus, by ceasing acorn production for several consecutive years, rodent numbers decline and some of the newly produced acorns, with fewer predaceous rodents around, will succeed in germinating and growing into the next generation of oaks.
Yet the relationship between oaks and field mice, at least, is more complex since field mice actually perform a valuable service for oaks. Gypsy moth larvae (caterpillars), which ravenously devour oak tree foliage, are consumed by field mice. Without field mice, oak trees could potentially be defoliated by moth larvae.
This is the perfect time to germinate acorns if you do happen to find an oak tree on which they are ripening. Pick them off the tree and remove their caps. Since acorns require stratification, or exposure to cold, in order to germinate, you will need to place them in a plastic sandwich bag and then store them in the vegetable compartment of your refrigerator for thirty days. During storage, examine your acorns from time to time. If you see any mold, wipe or rinse it off. Ideally, after a few weeks, you will observe roots start to grow from the pointed ends of your acorns. As soon as you observe these incipient roots, remove acorns and plant them either in the ground or in containers. Make sure your soil or soil mix is fast draining.
White or valley oak (Quercus lobata), native to the San Fernando Valley, is unique in having acorns that germinate immediately upon falling from the tree. If you walk beneath a valley oak in the midst of acorn drop, you will notice tiny white shoot tips protruding from acorns that litter the ground.
If you plant your acorns in the earth, they should be inserted so their top ends are level with the soil surface. As a precautionary measure, you will want to make a small cage, made from poultry wire, is placed in the loosened soil below each planting hole in order to keep gophers at bay. You will also want to cage each seed above ground to prevent mice and squirrel intrusions. Ideally, you would plant after a soil softening rain but, if no rain comes, just soften the soil with a spading fork prior to planting and make sure to water your acorns occasionally to keep them from drying out.
Seldom do people plant oak trees, or large trees in general, any more. Arguments against big trees are about money since no one can argue that big trees are more aesthetically pleasing than little or medium sized ones. Just visit the city of Claremont and you will quickly appreciate what large trees can do for the general ambience in an urban setting. When a city’s streets are lined with large trees it is positively uplifting and spiritually sustaining to to take a stroll. These days, before planting a tree, people think primarily about future pruning expense and the possibility of roots uplifting sidewalks.
Yet each time I see someone remove their lawn and replace it with artificial grass, I can’t help think about a simple alternative solution, namely, planting an oak tree. If you remove the lawn from an average-sized front yard of around 1000 square feet and plant an oak tree in the middle of it, you will have begun to create a drought tolerant, wildlife friendly ecosystem right outside your front door. Surround the oak with water-thrifty shrubs, perennials and self-sowing wildflowers, and you will have a created a vibant garden whose evolution you can enjoy for years to come.
Tip of the Week: We’re deep into November but ‘Waverly’ sage is still blooming. Then again, ‘Waverly’ always seems to be in bloom. It is a mysterious sage (Salvia species) of obscure origins and no one even knows how it got its name. In addition to blooming year around, or nearly so, it will absorb a frost just fine and may even survive temperatures in the low 20’s, unlike most Salvia species, which are much less cold tolerant.