Five things to do in the garden this week:
1. Heavy rain leaches salt and other compounds from the soil that inhibit growth and flower production. Perhaps that is why it seems that everything is flowering with such unusual abundance this year. The trumpet trees are partying in pink (Tabebuia rosea) and yodeling in yellow (Tabebuia chrysotricha) with reckless abandon. Pink jasmine (Jasminum polyanthum), whose buds are pink but open into white blossoms, are showing off blankets of white as they cling to fences, bowers, atria, and gazebos. The saucer magnolias (Magnolia x soulangeana) are resplendent with their pink, magenta, and purple tulip-shaped blooms, and the western redbuds (Cercis occidentalis) are aglow in magenta pink. As you drive between Mulholland Drive and Sunset Boulevard on the San Diego Freeway, the large shrubs you see blooming on either side of the freeway are California lilacs (Ceanothus spp.). This is an indication of how suitable this genus is for slopes and a hint as to what you might consider planting on your slopes — or on any other well-drained area of your garden — this spring.
2. There are three self-sowing succulents that no garden should be without. They are botanical cousins and all of them are at the peak of their beauty now. Mediterranean spurge (Euphorbia characias wulfenii) is a stunning domed plant consisting of a glorious conglomeration of robust, cylindrical to spherical masses of chartreuse flowers offset by blue-green foliage. A neighbor has allowed it to take over his front yard with the exception of two California lilac (Ceanothus spp.) shrubs that are flowering now and contrast with the abundant spurge. Silver spurge (Euphorbia rigida), also of Mediterranean origin, has chartreuse flowers complemented by silvery-blue, diamond-shaped leaves. Unlike Mediterranean spurge, however, there is no symmetry to silver spurge and it sprawls upon the ground. Snow-on-the mountain is an annual spurge but puts on rapid growth to the point where I once saw it growing as a three-foot-tall hedge along an entryway leading to the front door of a house in Atwater Village. All of these plants are ideal for a slope to which access is limited and an irrigation system is out of the question. They self-sow with no more water than winter rain provides.
3. If you have weeds growing in a part of your yard where, for now at least, you have no plans, you may want to cut the weeds down to ground level but not remove them, allowing the cut portion to rot in place. Weeds serve several useful purposes as opposed to bare ground. They aerate the soil with their roots, inviting microorganisms to proliferate with the improved aerobic conditions beneath the soil surface. As the weeds die, they decompose, enhancing soil fertility. Weeds also attract both beneficial pest-eating insects and pollinating insects too. Finally, weeds hold the soil in place, preventing erosion.
4. Greg Alder (gregalder.com) has provided guidelines for irrigation in summer, whose heat can now come at any time, so be prepared to water your fruit trees as follows, depending on canopy diameter. Where this diameter is two feet, provide two gallons of water a week; with a five-foot diameter, apply ten gallons per week; a tree with a 10-foot diameter canopy will need 50 gallons per week; a 15-foot diameter will require 100 gallons per week. Generally speaking, drip system watering frequency for an avocado tree is every three days, a citrus tree is every three days, and a deciduous tree is every five days.
5. A lemon tree is a classic addition to every Southern California garden and you can plant one now through the summer. Eureka is the favorite lemon variety since it fruits all year long, while Lisbon, whose fruit is similar to that of Eureka, produces in the fall. Improved Meyer is not as acidic as Eureka or Lisbon and has a thinner skin. It also grows on a smaller tree and thus is the preferred variety for container growing. Robert Ginn, a master gardener who handled landscaping at the Hollywood Bowl for many years, sent me an image of a large lemon that looked like it could be a Ponderosa, the giant among lemons that may weigh up to two pounds at maturity. Finally, you may want to consider a variegated lemon with fruit and leaves striped in green and cream and sometimes pink.
Do you have a plant that is colorful throughout the year and of which you are particularly proud? If so, tell me about it in an email to joshua@perfetplants.com. Your questions and comments as well as gardening tips and gardening questions are always welcome.