Although plants of every description experience a spurt in root growth this time of year, this is especially true of deciduous species — those that lose their leaves — since there is no competition whatsoever from shoot or foliar growth. Thus, when Paula Hayes, who gardens in Woodland Hills, recently emailed to ask about the best time to plant crepe myrtle (Lagerstroemia indica), Chinese elm (Ulmus parvifolia), and peach (Prunus persica) trees, all of which are deciduous, I answered without hesitation that the time is now.
When it comes to deciduous shrubs and trees, fall and winter are the seasons they get serious about root growth. In places like Southern California, where the ground never freezes, roots never stop growing. However, as long as leaves, fruits, and seeds are developing and ripening, root system expansion takes a back seat to growth of these above ground plant parts.
Another good argument for planting now, as opposed to waiting until spring, is that we can experience heat waves as early as April. It is much better for a plant to have established a strong set of roots heading into spring than to have just been planted when scorching weather suddenly arrives.
Ms. Hayes asked me to recommend peach tree varieties for our area. I recommend low chilling varieties such as ‘May Pride’ and ‘Eva’s Pride.’ These varieties are grown by Dave Wilson Nursery (davewilson.com) and Otto & Sons Nursery (ottoandsons-nursery.com). Contact them for names of nurseries in your neighborhood that carry their trees.
Deciduous fruit tree varieties are categorized by the number of winter chill hours they require to produce flowers and initiate fruit growth; the colder the winter, the more varieties you can grow (excepting northern states where spring frosts are the norm and would kill the flower buds of many fruit trees). This is a disturbing and counter intuitive notion for novice gardeners. Although plants are ultimately disqualified as garden selections based on their inability to tolerate the average coldest winter temperature in a particular region of the country, with deciduous trees it’s just the opposite.
The vast majority of deciduous fruit and nut tree varieties — whether apples, pears, plums, peaches, cherries, apricots, walnuts, or almonds — will never produce fruit or nuts in Southern California since winters here are just too warm for these varieties to flower, and without flowers no fruits will form.
The process of flower development in deciduous fruit trees is cold dependent. Every bud on a deciduous tree begins as a leaf bud. When winters are sufficiently cold, certain leaf buds differentiate into flower buds but when winters are warm, this differentiation does not occur and all you get are leaves. The vast majority of apple varieties will not produce in Southern California. They may show a lot of leafy growth and develop into robust trees, but not a single flower will appear.
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If you are considering which garden ornamentals to plant this time of year, you may be pondering the possibility of finding species that bloom in fall or winter. Before doing so, I urge you to consider species whose beauty is given primarily by their foliage since they provide garden interest in all four seasons.
Just the other day, I saw an arresting display of ‘Gold Mound’ Duranta with English lavender. English lavender will give a significant bloom for several months during the warm season but its greyish foliage is wonderful year around as a contrasting sidekick to gold leaf Duranta. Both plants grow 3-4 feet tall and wide.
Tip of the Week: Cranberry hibiscus (Hibiscus acetosella) is a reddish bronze foliar beauty, boasting rose-pink flowers as well, that is just now finding it’s way into the nursery trade and with good reason. You could easily mistake it, at first glance, for a burgundy Japanese maple on account of its deeply cut and serrated palmate leaves, each of whose five fingers comes to a point. This leaf is not to be confused with the maple shaped leaf on the Canadian flag either, as the cranberry hibiscus of the nursery trade, although a hybrid, finds its parentage in the tropics of central Africa. Still, cranberry hibiscus is actually hardier than the familiar Chinese hibiscus (Hibiscus rosa-sinensis) that flowers in red, pink, orange, and white.
Young leaves of cranberry hibiscus are edible but contain oxalic acid and should not be consumed more than once a week and only in small quantities. The plant grows rampantly, as much as six feet a year, and it needs to be regularly pruned to stay in bounds. It does not live for more than two or three years but is easily propagated from stem cuttings, which root easily in soil or water, at this time of year. Keep your rooted cuttings as indoor plants and then transplant them back into the garden in the spring.