These stars of fall flower gardens are starting to appear for sale in nurseries

There is a Chinese proverb that says: “The best time to plant a tree was 20 years ago. The second best time is now.”

This is a metaphor for doing something without further delay, even if it could have been done 20 years ago, since it is never too late to embark on a new venture and there is no time like the present to start. However, this proverb is not meant to be taken literally since although China, like the USA, has areas with mild winters, it also has Alaskan style winters in certain regions where temperatures reach 30 degrees below zero. And you would never plant a tree in such weather.

And yet, where the greater Los Angeles area – all the way up to the Antelope Valley — is concerned, you could take this proverb literally. As long as the ground does not freeze – and there is no record of it ever having frozen here — you can plant trees.

The best time to plant trees or any woody perennial is the month of October. Summer’s heat is usually broken by then, but the ground is still quite warm so that roots of trees planted at that time will grow rapidly even while the need for water is not as critical as it was during the previous months. Moreover, the wisdom of October planting comes from the fact that your young tree will have more than six months to settle in before the onslaught of next summer’s heat.

A fall application of a mostly phosphorus fertilizer such as bone meal is recommended for young trees in need of quick root system expansion since phosphorous is the mineral element most favored by roots. Note: bone meal is rich in phosphorus and, yes, since it comes from bones, dogs have been known to dig it up and dine on it. Although some dog food brands contain small quantities of bone meal, straight bone meal – as well as blood meal fertilizer, for that matter — can be toxic to dogs so keep this in mind when using this product where your canine critter is concerned.

The hole dug for your tree should resemble a satellite dish. It should be the same depth as the container in which it was brought home from the nursery and its diameter should equal at least three times the diameter of that container.  The most important roots on any tree are those in the top few inches of soil. Deeper roots are for stability and mining water during a drought but the roots that absorb most of a tree’s water and minerals are close to the surface. This helps explain the sagacity of mulch application since it offers a layer of insulation, keeping these shallow roots relatively cool and unstressed.

Horticulturally speaking, you can do almost anything in any season in Los Angeles, including tree planting, and so when I am asked what is the best time to plant or prune or fertilize I sometimes say, “Whenever you remember to do it.” It is best to prune nearly every kind of tree in the winter, but tree trimming companies stay in business by pruning in all four seasons and they would not be able to do so if pruning out of season was harmful to our local trees.

There is one practice, however, that is definitely seasonally dependent and that is bulb planting.  Strictly speaking, plants under the bulb rubric also grow from bulb-like organs such as rhizomes, corms or tubers but most get lumped together as bulbs for purposes of late summer to early winter planting. There are two broad categories of bulbs. Those native to Mediterranean climates such as our own – many of which are indigenous to South Africa — that do not require a significant dose of winter cold or any refrigeration to bloom and are best planted between now and September, and those known as Dutch bulbs (some require refrigeration and some don’t) which are not native to Holland but have been hybridized and glamorized in that country as if they originated there.

Some Mediterranean climate bulbs naturalize in the garden which means they proliferate as their asexual bulbous organs multiply underground and expand their presence. In this regard, bearded iris, Watsonia, crocosmia, nerine, Hippeastrum, and naked lady (Amaryllis belladonna) come to mind.

Foremost among Dutch bulbs is the tulip, whose habitat stretches from southern Europe to Central Asia. The word “tulip” has the same etymological origin as “turban,” a headdress that describes the tulip’s shape.

The three most famous Dutch bulbs – tulip, hyacinth, and crocus — must undergo a period of vernalization or exposure to cold temperatures in order to bloom. Place them in the crisper drawer of your refrigerator for six to 14 weeks. They may be planted anytime between November and January yet regardless of when they are placed in the ground, they will bloom between February and March. Treat them as annuals. Dutch bulbs that do not require vernalization and will also naturalize or spread throughout the garden from year to year include narcissus (daffodil), Hycinthoides hispanica (Spanish bluebells), muscari (grape hyacinth), and Dutch or bulb iris. Ranunculus, anemone, and freesia round out the Dutch bulb category.

The most wonderful display of Dutch bulbs may be ogled annually in Holland in Keukenhof Park, located twenty miles outside Amsterdam, in which 39 acres are devoted exclusively to seven million bulbs that are planted each fall. The garden is open to the public only eight weeks out of the year from mid-March to mid-May when the millions of bulbs burst into bloom. You can view spectacular photos of the bulb display at albertdros.com and enjoy a video tour at keukenhof.nl. The display is continual over these eight weeks due to the planting method, where three bulbs are placed in each hole, one on top of the other. The topmost bulb blooms first, followed by the one beneath it and, finally, by the one on the bottom.

Chrysanthemums, of East Asian origin, have begun to appear in nurseries. They are the stars of the fall flower garden. Although grouped with sun-loving autumn annuals such as snapdragons, pansies, and Iceland poppies, chrysanthemums will live for several years or more as fall-blooming perennials. The one caveat to growing chrysanthemums as perennials is that they tend to flop over unless tied or staked in an upright position. After flowering is over, they should be cut back considerably so as to assume a bushier stature for the following year’s growth. Miniature chrysanthemums are ideal for hanging baskets and containers.

Tip of the Week: Jeanie Muehl of Garden Grove sent the following email: “I have had my plumeria for lots of years but I have never had a problem like this. The leaves start to turn yellow, curl and disfigure, and fall off. There is also some powdery mildew and some whitefly. I think it must have every disease available and probably has the COVID virus!”

The first problem you mention is a result of “tentative Steven’s leafhopper,” an insect that was initially identified on a plumeria in San Diego in 2015 and has moved throughout Southern California since then. It is 1/8 of an inch long and looks like a mini-grasshopper.

An unmistakable symptom of its presence is “hopperburn,” where the leaf yellowing you mention eventually takes on orange, red, pink, or bronze tints. Sprinkling 3 in 1 Rose and Flower Bayer systemic granules around the base of your plant and immediately watering it in is recommended by Don Doerfler of the Southern California Plumeria Society. You can also release beneficial insects that prey on leafhoppers such as parasitic wasps, ladybugs, lacewings, and pirate bugs. Keep leaves hosed down and dispose of fallen leaves immediately because they may contain leafhopper eggs.

What you describe as powdery mildew, if it appears on leaf undersides, might actually be milky plumeria sap which is left where leafhoppers wound leaf surfaces when feeding or depositing their eggs. Whiteflies are deterred by applying a layer of earthworm castings around the plant.  Plumeria is in the same plant family as oleander, which was plagued for years by a leafhopper (the glassy winged sharpshooter) that was eventually brought under control by the release of parasitic wasps.  It is hoped that a similar type of wasp will soon be found to control the leafhopper that is currently wreaking havoc on our plumerias.