Keeping your citrus trees healthy and more to do in the garden this week

1. David Herrig sends the following prescription for successful growth of a dwarf Satsuma mandarin tree: “We purchased ours from Home Depot back in 2002 when we lived in West Covina. It lived in a pot on our patio through 2014 when we moved to Pomona. The only issue we had in the pot was insufficient drainage. I drilled some holes in the bottom and set the pot up on blocks rather than directly on the cement. We fertilized it 4 times a year starting in January according to a schedule we got from the San Gabriel Valley Tribune. We use the citrus/avocado food from Home Depot. In January 2015, we planted it in the backyard here in Pomona where it has thrived ever since. We continue to fertilize on the same schedule and it gets water every other day when it is not raining. The soil here is very sandy so it does not hold water. Starting in mid-to-late November every year and continuing through January we harvest and eat at least 5 or 6 dozen Satsumas of various sizes.”

The citrus fertilization schedule to which Herrig refers was the recommendation of legendary horticulturist, the late Jack Christensen, who penned the Five things to do in the garden and more in Southern California News Group publications for many years. “Mature citrus trees need a yearly total of 1.6 pounds of actual nitrogen fertilizer,” Christensen wrote, “divided into four equal portions applied in late January, early March, late April and early June – about six weeks apart – and distributed around the drip line. Since one pound of any dry fertilizer equals about two cups, that is about four cups of ammonium sulfate, two overflowing cups of ammonium nitrate, or 1.5 cups of urea, each time you apply it. Be sure to water it in well.” The fertilizers listed by Christensen may not be available and so you can use a citrus/avocado formula, as suggested by Herrig, instead.

2. In Los Angeles, spring comes in February and proof of this can be seen in flowering peaches, pears, plums, apricots and cherries with their blinding clouds of blooms. The “flowering” moniker indicates that these fruit trees are grown entirely for their flowers since fruit either does not form or, if it does, it is not edible. An exception would be certain flowering plums whose fruit can be eaten although it is tart as opposed to sweet. Descanso Gardens is worth a visit if only to see its bellflower cherry tree (Prunus campanulata) covered in dark pink bell-shaped blooms. Along the periphery of Lake Balboa in the San Fernando Valley, you can see dozens of luminous Pink Cloud flowering cherries (Prunus serrulata var. Pink Cloud). And Huntington Gardens has long been famous for a gnarled but resplendent Japanese flowering apricot (Persica mume) that blooms about this time. Also included in this group are evergreen pear (Pyrus kawakamii), a massive globe of blinding white flowers, flowering plum (Prunus cerasifera cultivars) with usually pink but sometimes white flowers, also know as purple leaf plum due to bronze purple foliage, and Peppermint flowering peach (Prunus persica) whose blossoms are variegated pink and white. 

3. Monrovia Nursery has a list of perennials and annuals to plant for early spring color. They will start to bloom as soon as temperatures warm which, in this part of the world, could be only a month from now. One of Monrovia’s recommendations is Hellebore. This rhizomatous species has flowers whose colors are often understated but appear in yellow, pink, salmon, red, and purple to nearly black, as well as white. Foliage is often bluish-green. Hellebore is a clumping plant that is the perfect candidate for a semi-sunny to shady garden. Dianthus is a long-blooming biennial (that is, it takes at least two seasons of growth to bloom) or perennial, depending on the species. And then there’s the gerbera daisy. Gerberas are probably the happiest plants on earth as their large daisies in vivid yellows, oranges, pinks, and reds may well be described as boundless botanical smiles. Although Monrovia lists it as an annual, I have seen patches of gerberas persist for decades. The key is to grow them in a very fast-draining soil. Gerberas also make outstanding cut flowers, or you can just cut the flower heads and float them in shallow bowls. Monrovia has a new variety of Agapanthus or lily-of-the-Nile known as Baby Pete which seldom forms seeds and thus flowers for a longer period of time than conventional Agapanthus types. Seed formation on any plant depresses subsequent flowering.

4. To keep your houseplants healthy, give them a quarter turn each week to keep them symmetrical, allowing sun to reach each of their four sides in equal measure. For more compact plants, pinching of new growth is required. If your plants become leggy due to lack of light, improve illumination with a LED light. Gooseneck LED lamps are ideal for desk plants. Any sign of etiolated (light-deprived) or stunted growth is a warning sign since disease and insect problems may occur when plants are stressed by lack of light or, for that matter, any other factor. You want to delay fertilization until new growth begins. Slow-release fertilizer pellets that break down quicker in warm weather are probably a safe bet since their outer coating is not likely to dissolve until prime growing conditions return. This is the proper moment to air layer plants that have grown too large for their location or their pots. With air layering, you remove an outer ring of stem tissue and cover it with moist peat moss that is enclosed in plastic wrap and tied off on both ends. Roots will eventually begin to grow and when you see they have made a robust cluster, you can cut the branch above and below the rooted segment and pot it in its own container.

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5. This is the time to weed, especially where the soil is still moist from our heavy rains. Where soil is dry, it is advisable to water it the day before you embark on your weeding project. When soil is moist, it is much easier to pull out your weeds along with their root systems so resprouting cannot occur. If seeds are formed, it is not enough to pull the weed and drop it in place, even if it will eventually decompose and improve soil fertility. Those seeds will eventually germinate where they lie. On the other hand, by removing weeds before they flower, you can distribute them around your plants as mulch or put them in your compost pile. Actually, though, if your compost pile is hot enough,even weeds with seeds can be tossed in since the seeds will die from the heat before they can germinate.

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