Category Archives: watering trees

Watering Tips when Planting for the Birds & Bees

Western Tiger Swallowtail butterfly

I may not be so fond of gophers but I never tire of the birds, butterflies and bees that visit my garden. I’m always on the look out for plants that will attract even more of these exquisite creatures and it’s one of the top requests for nearly every garden that I design. Fortunately there are many plants that fit the bill and have low water requirements for our summer dry climate.

Trees that provide fruit, seeds, nectar and protein from insects attract many kinds of songbirds. Our native Big Leaf Maple is a favorite of the Evening Grosbeak who relish the seeds and early spring buds. Another bird magnet is the dogwood. Our Pacific dogwood as well as the Eastern dogwood and even the hybrid of the two, Eddie’s White Wonder, all are very valuable sources of food for many birds. Their summer berries are high in fat and important for migratory and wintering birds.

Lesser goldfinch

There are many great low water-use shrubs and perennials that attract birds. My favorite Lesser Goldfinch is partial to the seeds of yarrow, buckwheat and aster. Kevin’s mahonia is favored by Western bluebirds. Blooming now in our own neck of the woods is Mexican elderberry. Their butter yellow flowers will form purple berries rich in carbohydrates and protein and attract an incredible number of birds. And I always can find space for another variety of manzanita or ceanothus.

Mimulus ‘Jelly Bean Gold’

Both hummingbirds and butterflies are attracted to flowers that provide nectar. Among their favorites that won’t break your water budget are natives such as penstemon and salvia. galvezia, mimulus, monardella. California fuchsia and ribes are also important nectar sources for birds in your garden. Add a couple non-native, drought tolerant perennials like lavender, gaura, coreopsis, verbena, scabiosa, lantana and wallflower and you’ll provide a feast for all your winged visitors.

So how much water do different types of plants need during the heat of summer?

As a rule of thumb, trees and large shrubs need deep but infrequent waterings. They should be on a separate valve than your smaller shrubs and perennials. Water ornamental trees 1-3 times per month depending on the type and soil. Tree roots grow 12-36” deep and require 10 gallons of water per inch of trunk diameter.

Sambucus nigra berries

Apply with a soaker hose, drip system emitters or hand held hose with shut off and soft spray attachment according to your water districts restrictions. Don’t dig holes in the ground in an effort to water deeply. This dries out roots even more. Be sure to water the root zone to the indicated root depth every time you water. Watering deeper than the root zone only means you are wasting water. You can test how deep you watered by pushing a smooth rod -1/4” – 3/8” in diameter- into the ground soon after you irrigate. The soil probe should easily slide through the wet soil but become difficult to push when reaching dry soil.

The roots of smaller shrubs are 12-24” deep in the soil. Established native shrubs may need only monthly irrigation to keep them looking their best while other shrubs may need watering every 7-10 days during the heat of the summer. Perennial roots only go down 12” or so and may need watering once or twice a week depending on type.

With lots of mulch and the above watering tips you can keep all your plants happy and healthy for the birds, butterflies and bees to enjoy.

Save Water – Save Trees

I had to do it. I couldn’t resist. Even though I’d vowed not to get any new plants until fall planting season when I saw the one gallon Pride of Madeira just begging for a new home I succumbed to my impulse. I rationalized this plant was on my wish list and will be drought tolerant so I wasn’t being totally irresponsible.

I’ve always wanted an echium fastuosum on my hillside. I admire those huge spires of purple-blue flowers whenever I see them in other gardens. These are tough plants getting by with no summer water once established and the flower spikes are bee magnets. I covered it with a layer of shade cloth for a few days because it was so hot when I planted it. This will help it establish more quickly while the roots take hold in the soil.

Flame_tree
Flame tree on Stanford campus

In your own garden it’s wise to establish a drought to-do list. I’m talking about what plants get your precious water and what to let go.

As we enter another dry year many of our ornamental and fruit trees are dying. Many were watered along with the lawn you have now let go brown. Others might have been surviving on natural rainfall. Whatever the case in your garden don’t let your trees die.

Nature has already killed an estimated 12 million trees in Calif. forests since the drought began four years ago. Most of these have fallen victim to bark beetles that attack trees weakened by drought.

In our own neighborhoods, trees are a long-lived asset. A tree is not something that can be easily replaced. It’s OK to appropriately water trees. Dying trees can be a safety hazard and removing a dead tree is expensive.

It takes years to grow a tree to mature size. Save and use shower and cooking water to help them out. Maybe it’s time to install an simple laundry-to-landscape system to water your landscape trees. Or set up a separate drip or soaker hose for your trees and give them a good deep drink at least once or twice a month. And remember that the tree’s feeder roots are not at the base of the trunk but out at the drip line and a little beyond.

laurel tree.1600
Laurel tree on Stanford campus

A rule of thumb for determining when to irrigate is when 50% of the water has been depleted from the soil in the plants’ root zone. This allows a buffer of water in the soil in case the weather suddenly turns hot and windy and applies to trees, shrubs and perennials.

Sandy soils hold less water than clay soils and must be irrigated more frequently. A common misconception is that it takes more water to grow plants in sandy soil than in clay soil. Actually the total amount required for the whole year is the same for both soil types. The amount of sunlight, wind, temperature and humidity control how much water a plants needs – the soil is only the reservoir.

To check the water content in the soil dig 8-16 inches down into the soil with a trowel, shovel or soil tube and feel the soil. At about 50% available water:
* Course soil appears almost dry and forms a ball that does not hold shape.
* Loamy soil forms a dark ball that is somewhat moldable and can form a weak ribbon when squeezed
between the finders.
* Clayey soil forms a good, dark ball and makes a ribbon an inch or so long and slightly sticky.

If you are planning to plant some new trees this fall, be sure they are drought tolerant natives or low water use non-natives. There are many nice specimens to choose from. And don’t skimp on the mulch.

It’s important to maintain our existing tree canopy and plant for the future. Even in times of drought, no especially in drought, planting and stewardship of trees is critical. Not just for their future but for ours as well.