Exploring the magic of mulch and minimal watering at Descanso Gardens
The largest plant family is the daisy family (Asteraceae), with over 32,000 species worldwide. Its diversity is lavishly exemplified at Descanso Gardens in La Canada Flintridge, where I was recently a visitor. The Gardens, located at 1418 Descanso Drive, are open 9 a.m.-8 p.m. Mon-Fri and 9 a.m.-5 p.m. Sat. and Sun. For more information, go to descansogardens.org.
As soon as you enter the driveway from Descanso Drive, look to your right and you will see impressive compact shrubs with yellow daisies. With the assistance of Autumn Ayers, Descano’s plant records coordinator, I learned the name of this and a number of other species in the gardens. This one is known as Canary Island daisy (Asteriscus sericeus). Its drought tolerance is promoted by leathery, yet vibrantly glowing foliage, and it tolerates cold down to 25 degrees. It is grown by San Marcos Growers and you can find a retail outlet near you that carries it at smgrowers.com.
Near the Canary Island daisy are California native members of the buckwheat family: St. Catherine’s lace (Eriogonum giganteum), currently blanketed with creamy white flowers, and seaside buckwheat (Eriogonum latifolium rubescens), which is nothing but a mass of pink flowers at this moment
Moving on to the ticket window for an encounter with another daisy family member, a stunning specimen of variegated tractor seat (yes, the leaves are shaped like tractor seats) or leopard plant (Farfugium japonicum var. Argenteum) awaits you there. While it does produce clusters of yellow daisies, its leaves are eminently suited for ogling, reaching up to one foot in diameter. The shiny white splotches on the leaves light up a partially shaded garden bed and the plant is well-suited to container growing. It will die to the ground when temperatures plummet but will grow back up again when weather warms thanks to its rhizomes.
Entering the flower garden just beyond the main entrance, I was dazzled by the colors on display. Each plant was covered with blooms, an unexpected pleasure in the middle of July during a sizzling heat spell. Normally, heat depresses flower production, but not here.
Speaking with David Bare, director of horticulture, I learned that the drip system in place provides water twice a week for 10-15 minutes per application. The presence of mulch mitigates against evaporation of water from the soil surface and keeps roots cool so that there is less stress overall and the plants can simply flower in carefree delight.
Among the many blooming beauties, my attention focused on some fiery orange coneflowers (Echinacea purpurea), completing the triumvirate of daisy family members that caught my eye at Descanso Gardens. Coneflower is a perennial that is not that widely grown in our area, perhaps because it is native to prairies and woodlands (from Virginia to Iowa, from Florida to Texas) where, despite dry periods, rain can be expected to fall on and off throughout the growing season. Coneflowers — also available in pink, white, yellow, and red — do best in full sun although they accept some shade and are not bothered by freezing weather.
Coneflower maintains its sturdiness when cut, holding its own in vase arrangements for more than a week. It has a clumping growth habit and will spread slowly from year to year, although its lifespan in our area, based on Bare’s experience, is around three years. Coneflowers attract birds, bees, and butterflies and will self-sow. They prefer a fast-draining sandy loam soil but can also find their way in clay.
Bare informed me that the flower garden which captured my attention is populated with plants selectively chosen for their minimal water requirement and — with the home gardener in mind — relative ease of cultivation. The particular species chosen also ensure that there will be flowers on one plant or another in every season. Still, it seemed like all of them are blooming now, which is a credit to their meticulous care. I would imagine that deadheading, where flowers are removed as soon as they fade so that others will be encouraged to grow and take their place, is a daily chore.
I was thinking that there must be some sophisticated fertilization regime in place to ensure that foliage is deep green and plants are full of flowers. Perhaps liquid fertilizer through the Netafim drip tubing? The answer was no. “We use some compost when planting and keep a continuous mulch around the plants,” Bare said. “Actually, we are more religious about the mulch than the compost.
There could be no better proof that a continuous application of mulch is all plants need to thrive. Mulch breaks down into the mineral elements that plants need for healthy growth. You might be wondering: Is this some sort of fancy mulch that I could never afford? Again, the answer is no. Bare uses the same mulch available to all of us – the chips found in any tree trimmer’s dump truck. Stop a tree trimmer and explain your need. You will soon find a truckload of mulch on your driveway since it will save the tree trimmer the time and expense of going to the dump. Just make sure you have the help you need to wheelbarrow your free mulch into your yard and place it around your plants, taking care that the mulch does not touch trunks, stems, or leaves since such contact could lead to fungus problems.
For the record, when it comes to the Descanso camellia collection, which is the largest in the world, Bare topically applies a granular organic fertilizer that is formulated for acid-loving plants.
Close by the aforementioned flower garden is a wonderful species of Eucalyptus that deserves wider recognition. Known as Moon Lagoon or fine-leafed mallee, it has oval-shaped gray-green juvenile leaves with a purplish cast. Leaves of the mature plant are greener, wispy and slightly curved, unlike any other Eucalyptus you have ever seen. Moon Lagoon makes a soft informal evergreen hedge, as it grows to a height of 12 feet. Still, if you are more inclined to enjoy the fragrant, silvery juvenile leaves, you can keep it pruned to a height of 3-4 feet. This juvenile foliage is a favorite of flower arrangers, providing filler for colorful bouquets and persisting for two weeks in a vase. Moon Lagoon is also available through San Marcos Growers.
A mallee is a type of eucalypt that grows from an underground structure known as a lignotuber. Mallees tend to be shrubby rather than arboreal although some can grow as tall as 30 feet. Multiple stems grow out of a single lignotuber so that the foliage on each stem may shade its neighbor, often resulting in a small mallee “forest” of genetically identical, if spindly, tree-like clones.
Tip of the Week: I remembered noticing considerable infestations of nutsedge (Cyperus esculentus), also known as nutgrass, while on previous visits to Descanso Gardens. This time I did not see any. I asked David Bare how to cope with nutsedge and he described three practices which, used together, offer effective control of this weed: “Hand-pulling, mulching, and planting ground cover” to compete with the nutsedge. I have also seen soil solarization used for nutsedge conrol – where a weedy area is soaked this time of year with a hose and then covered with clear plastic; the steam generated under the plastic kills the plants including their underground tubers or “nuts.” However, no matter what you do, Bare notes, you will never be totally rid of nutsedge.
Nutsedge is native to Egypt, where its edible tubers are harvested and roasted. It is related to several water-loving plants that are suitable for growing in ponds. The most widely seen is the umbrella plant (Cyperus alternifolius), which may pop up almost anywhere and will spread with weedy determination unless it is relentlessly chopped back or uprooted. Umbrella plant grows up to 5 feet tall with many parasol-shaped leaves. It is valued, in some quarters, for its durability as a container plant, whether on the patio or indoors.
The most famous nutsedge relative is papyrus (Cyperus papyrus), encountered both as an aquatic and partial-shade garden specimen, growing to 6 or 7 feet tall. Misled, perhaps, by its somewhat wispy and delicate-appearing foliage, some people make the mistake of giving papyrus too much shade, which will inhibit its growth or kill it outright. Make sure that papyrus has good ambient light, but take note that King Tut, a 2-3 foot tall dwarf papyrus, is a bit more shade tolerant.