Newly planted trees need a steady supply of water and this reality presents a special challenge when the trees in question are planted in parkways along city streets. In Los Angeles, the concrete parkway sidewalks and asphalt streets that border or surround such trees reflect light and radiate heat onto the freshly planted trees, causing them considerable heat stress. It appears, however, that a solution for this dilemma is at hand.
Just the other day, driving west on Ventura Boulevard, in Tarzana, as I approached Reseda Boulevard, I noticed brown plastic donuts encircling young parkway trees to my right. Upon closer inspection, I saw that “treepans.com” was stamped on the donuts.
I contacted the company through the website and was informed by Ben Brown that these TreePans, as they are called, had been installed by the Los Angeles Conservation Corps. Brown also expanded on their purpose. “Water that evaporates from the soil around the tree condenses on the underside of the top of the tree pan,” he explained, “and then drips back onto the soil. This keeps the ground moist and serves the same function as mulch in preventing evaporative water loss from the soil.” The advantage of a TreePan, as opposed to mulch, is that mulch will absorb and take away some of the water that would otherwise be taken up by roots.
One of the major benefits of the TreePan, whose diameter is three feet, is protection of the tree trunk: protection from lawn mowers and string trimmers (weedeaters), protection from rodents which can also nibble on roots, protection from grass and weeds competing with the young tree for water and minerals. The opening around the trunk may also be enlarged as the trunk caliper (diameter) increases in size, all the way up to one foot.
Several other devices, known generically as tree cocoons, are available for the protection and sustenance of newly planted trees. These devices are essentially water reservoirs, designed so that the water within never evaporates but is slowly made available – at the rate of 3 ½ tablespoons per day — to plant roots by means of wicks that reach the soil through tiny holes in the bottom of the cocoons.
The WaterBoxx and Growboxx (groasis.com) are designed so that, once their twin water holding reservoirs in either box are full, the newly planted tree, as long as it is native to the area or compatible with the local climate, should never need to be watered again. The lid of the box channels rain water and dew into the reservoirs so that as long as you have 10 inches of annual rainfall (5 inches less than the Los Angeles average) and regular dewy nights, the reservoirs will always be full.
Even when rainfall is scarce, dew alone, every drop of which is funneled from the hydrophobic lid into the water reservoir below, may be sufficient to sustain your tree. Ancient Nabatean farmers in the deserts of the Middle East, for example, nurtured grapevines by surrounding them with stones that, beveled towards the vines, trapped and directed dew directly to vine roots.
The Growboxx is biodegradable but lasts for three years, by which time the young tree, especially if it’s a California native, should be able to stand on its own, without supplemental irrigation.
The plastic Waterboxx, on the other hand, may be recycled any number of times. Growth in both boxes is remarkably faster than trees grown by conventional methods, including drip irrigation. The reason for this is not only due to daily, if parsimonious, application of water through wicks but to the insulating property of the water cocoon that surrounds the tree. The water reservoir keeps the tree cool in summer and warm in winter, stress free and always primed, when temperatures allow, for a burst of new growth.
Both of the above devices have been successfully utilized in growing trees on nutient poor or depleted soil, from deserts to abandoned mining sites.
The COCOON (landlifecompany.com) is a single, covered, biodegradable reservoir with a tree in the middle. Americorps has planted COCOON seedlings in the Santa Monica Mountains and will be planting thousands more in reforestation of wildfire ravaged areas.
All of the three tree cocoons mentioned above utilize mycorrhizae as a growth supplement. Mycorrhizae are fungal organisms that live in symbiosis with plant roots. Mycorrhizae not only make certain minerals more available for root uptake, but increase roots’ water absorption capacity as well.
What do these tree planting and nurturing devices mean for the backyard gardener? Well, for one, it makes it possible to plant an orchard, for example, without an irrigation system. Cocoons keep the soil moist without a need for supplemental irrigation of any kind.
If you have an area of your property, such as a slope or a side lot, that you never planted because the expense of an irrigation system ruled it out, you might want to reconsider now that these tree/plant cocoons are available.
Here’s another advantage to cocoons. Let’s say you want to plant a new landscape of trees and shrubs but need to go out of town soon afterwards. Relying on an automatic irrigation system is always a worry due to power outages, line breaks, and clogged emitters. With cocoons, you just plant and walk away since no supplemental irrigation is required.
Finally, where California natives are concerned, cocoons seem the perfect vehicle for making sure your plants are properly watered – which can be a tricky proposition the first couple of years after planting — until they become established and can fend for themselves.
Tip of the Week: Ronald Chong, our faithful correspondent from Hacienda Heights, emailed a picture of a kumquat tree heavy with fruit, wondering which variety it is. He gives it regular water and timely doses of citrus fertilizer which helps to explain its magnificent yield.
It’s more than likely that this is a ‘Nagami’ kumquat, the most popular and available variety. The fruit of ‘Nagami’ is consumed whole. While kumquat pulp is always bitter, the peel of ‘Nagami’ is especially sweet which makes it a wonderful snack in late winter and early spring when the fruit are present. During summer, fragrant kumquat flowers are a nice accompaniment to any garden experience. The fruit is also highly ornamental against a backdrop of lush green leaves.
Other attractive feautures of ‘Nagami’ include its manageable size (which tops out at 8 feet tall and 6 feet wide), its cold hardiness (down to 20 degrees Fahrenheit), its resistance to pests and diseases, and its ability to grow in almost any soil type. It also makes a satisfying subject for a patio or balcony container and may even be grown indoors in a sunroom or where there is an extremely bright and sunny exposure.