Imagine being responsible for all the lives of these noble spirits, when they are planted at the hands of you and yours. Plant Redwood and Ash and Maple and Cottonwood and Oak and Sycamore. The earth gives thanks. The Egrets return. Life is good.
Redwood trees live a thousand years, when the climate makes them happy. But here in this northern California valley of Santa Clara, or silicon, south of the cool native redwoods in the coastal mountains, drenched out here by abundant sun and little rain, they take special nurturing if they are to live well.
When the earth is impacted by the repeated crossings of heavy equipment, 20 ton tracked vehicles used for road construction, for example, trees cannot live well. When the earth is covered for two or three feet with a layer of rock and gravel, with a clay
content of less than 50 percent, trees cannot live well.
Do you want to plant trees in this soil? Do you want them to live well? Fixing the problem is easy, if you have a truck mounted, 24 inch diameter auger. Make sure that your truck is convertible to either tracks or 4 wheel drive with knobby balloon tires, since many of the trees are needed on steep embankments.
Do you want happy urban trees? Well then, simply drill a 24 inch diameter, 4 foot deep tree holes in the impacted soil. Then interconnect with deep trenches all of the holes to each other and to a drainage grade using a 6 inch wide, two foot deep 20 horsepower trencher. Refill the holes and trenches with a mix that incorporates at least 70% of the original dirt (with big rocks and boulders removed), 15% imported sand (get a dump truck for this), and 15% (or less, avoid overdoing it here) imported planter’s mix (you know, potting soil).
Then plant the trees in the refilled holes. Your trees should have be at least 4 feet tall and should have at least a 12 inch deep, well developed root ball. They are being thrown to the wolves. A two inch diameter, eight foot stake, at least one per tree, is recommended.
The more trees you plant together the better. Their canopies and their root systems will interconnect, allowing them greater wind stability and moisture retention.
The urban forest is a technological forest, an artificial forest, one that must be maintained if it is to thrive, and your job isn’t done yet. Water the trees via bubblers (all of them adjustable up to 30 gallons per hour each) which drip into a 4 inch diameter 2-4 feet deep gravel filled PVC pipe (perforated every 3 inches on the pipe surface with 1/2 inch diameter holes), into a 6 inch diameter three foot deep hole. Make sure there are nearly as many bubblers as trees, and position the bubbler holes adjacent to either trenches or tree basins. Another method that works on freeways and places where the systems will be undisturbed is to use soaker hoses. Your watering system should be on an automatic timer and you need to water the trees once per week all summer long (enough to fill percolation basis around their canopies) for their entire lifespan.
If all that heavy equipment is too rich for your blood, prepare to do it yourself. You will need to spend a season breaking earth with a pick and digging it out with a shovel and hauling it around with a wheelbarrow. Give yourself a break, using the 2.5 pound pick as much or more than the 5 pound pick, and try to alternate between a right handed stance and a left handed stance. You should probably get yourself a good pair of gloves, too, and be sure to wear safety glasses when you are breaking through rock. You may need a 20 pound “breaker bar.” And remember to install that watering system, while you’re at it…
Then plant an urban tree grove, and watch it thrive. Every 10-20 years you should consider planting, removing or replacing trees throughout the grove in order to keep its total biomass increasing as fast as possible. It will bring our global carbon debt down.
Yeah, and it will make it nicer too. We know, Gilligan.