My neighbor is a very active and observant bird watcher and on my daily dog walk he told me to take a look at the stand of Chinese pistache trees down the block. “They're full of red berries and the little birds are feasting on them,” he told me. “You might even see a yellow Wilson's warbler; they're migrating now.” I didn't spot any warblers in the trees, but did see about 30 noisy finches and sparrows flitting around the berry clusters.

I had never noticed that those three trees were loaded with berries and full of small birds in fall. Maybe that's because almost all the trees in my neighborhood are male varieties; it's rare to see female or flower and fruit-bearing landscape trees in any neighborhood.

The rationale for planting only male trees has been that female fruit, nut and seed-bearing trees trees create litter that can make a mess on sidewalks, patios and cars. They can also attract rats, squirrels and other vermin. Male trees aren't as messy, but they do produce pollen – one of the main reasons allergy problems have increased in recent years. Nurseries often stock only male trees.  

According to a report on the Audubon website, the population of birds in North America is nearly three billion fewer than in 1970. Other sources state that 90% of the decline in the U.S. bird population is in just 12 bird families, including small warblers, sparrows and finches, seed and berry-eating birds that are very common in our urban neighborhoods. The decline is driven by climate change, heat stress, urbanization and the loss of agricultural land. Some birds – including crows, riparian black Phoebes and Anna's hummingbirds – have been better able to adapt to changing conditions, unlike desert birds whose populations have plummeted. 

We try to encourage home gardeners to plant bee- and pollinator-friendly gardens that include a variety of flowering plants that bloom at differing times in order to provide a constant source of pollen and nectar for beneficial insects (and hummingbirds). We might also stress the need to plant a variety of flowering trees and bushes in home gardens, which will provide shelter, nest-building materials, habitat, seeds, fruit, sap and insects for birds throughout the seasons.

Native trees, which will attract and feed native birds, are the obvious first choice, but finding them can be difficult. Many new housing developments have very limited yards or green space and lack parking strips where trees can be planted, so size at maturity is another factor. Nursery labels often don't indicate whether trees and bushes are native, whether they produce seed that is edible for birds, or when fruit and seed production will take place. However, more local nurseries and garden centers are setting aside space for and emphasizing native plants, and their staff is becoming more knowledgeable.

The most bird-friendly Central Valley gardens would include a few smaller evergreen conifers, one deciduous fruit or flowering tree, two or three groupings of perennial seed and berry bushes as well as flowering annuals and perennials that bloom over the length of the growing season and hold seed through the winter.

Sources:

Plant Native Trees That Attract Birds, Birdsandblooms.com, Jan. 21, 2022   

Climate change, urbanization drive major declines in birds, UC Berkeley News, Feb.22, 2023

North America has lost more than 1 in 4 birds in the last 50 years, new study says, Audubon, Sept. 19, 2009

"The Allergy-Fighting Garden," Thomas Leo Ogren, 2015, Ten Speed Press, ISBN: 978-1-60774-491-7

 

Fall has arrived on the calendar but the summer heat continues. October is the best month to plant and transplant here in the Central Valley but once again this year we're having to postpone fall planting until daytime temperatures are consistently in the 80s. Weather forecast models show that it will probably be mid-October before Central Valley gardeners can risk planting.

Nurseries and garden centers also wait until temperatures are cooler before risking bringing in their fall stock. Our fall planting season usually ends in mid-November. We may well have just four weeks or fewer to plant seeds and transplants of cool-season vegetables and spring-blooming annuals instead of the used-to-be-normal six weeks of fall planting time that encouraged stronger growth and root development before cold winter temperatures arrived.

‘Hardening off' allows nursery transplants to adjust to the differences in light conditions and temperatures in the garden by spending several days in a sheltered spot outdoors in their nursery containers or cell-packs before planting. That period of adjustment will be a critical step this year.

Amending garden soil two weeks before planting by adding copious amounts of humus and compost will improve the soil's water retention and drainage. Regularly amending the soil is another critical step in helping seedlings and transplants develop healthy, extensive root systems that aid in surviving higher fall temperatures and heat spikes.

Many large landscape trees are looking pretty shabby at the end of this September. Some have already dropped most of their leaves and many branches look to be dead or dying. This summer's brutal heat clearly stressed them to their limits.

Trees planted in parks, lawns or parking strips which received shallow sprinkler irrigation rather than regular, slow and deep irrigation will show more signs of early senescence or untimely decline. Give all landscape trees, young and old, a really deep soaking (or two or three depending on temperatures and the tree's condition) this month. Deep irrigation allows root systems to take up enough water to sustain trees as they enter winter dormancy before the winter rains arrive and also promotes full dormancy and more vigorous growth in spring.

This summer really tested the capacities of heat and drought-tolerant plants to survive extremely high temperatures. The high temperatures also negatively affected bee, butterfly, bird and beneficial insect populations. If replacing plants that died or that are so damaged that it will take months to recover, consider replanting with flowering perennials and annuals that provide food, pollen, habitats and shelter for a variety of beneficial species. California native plants should be among the first choices.

Nursery and garden center labels may not indicate which flowers attract which beneficials but many seed companies now provide that information online and on seed packets. Try to plant all of the three flower types (umbrella, tubular, open) as well as bushes that produce edible berries. Add a fountain to your landscape to provide clear, trickling water for bees and baths for birds and keep the bird feeders cleaned and filled this winter.

The damage to plants from extreme heat spikes this June and July is now obvious. Mature drought and heat-tolerant sycamores that did not receive regular deep irrigation have lost two-thirds of their leaf canopy. Crape myrtles that should be in full bloom in summer have lost nearly all of their blossoms. Lawns grasses have turned to yellow straw, rose petals look fried (they are) and fruit trees are dropping most of the immature fruit well before harvest time.

Consecutive weeks of daytime temperatures exceeding 100 degrees and nighttime temperatures remaining in the high 70s have killed many plants and trees and weakened or stunted many others. Determining whether severely heat-stressed plants and trees are dead or dying and whether they have a chance to recover vigor and good health will be a challenge during the next few months. Branch dieback, premature leaf drop, dropping of immature fruits and nuts, dead leaves, blossom drop and flower desiccation as well as yellowed or brown lawn grasses are all signs of severe heat stress as well as drought stress. 

Determining the extent of the heat damage this next month will determine whether a plant or tree is salvageable. Dead leaves don't necessarily indicate that a plant has died. Remove dead leaves on flowering annuals and summer vegetables and scratch the stems to check for green tissue underneath the top layer of bark or stem tissue. Green tissue is still alive. Check leaf nodes for swelling which indicates that new leaves are forming at the node.

Keep the soil moist and delay removing plants which show signs of life. They may well recover and begin producing again in late August.

Protection from the scorching sun this month will speed recovery when temperatures cool in fall. Try to provide full shade this month for damaged plants or plants that do not recover easily from wilting. Move container plants into full shade. Place market umbrellas and shade structures where they can provide the most shade and leave them there. 

If major structural branches on mature landscape trees and fruit and nut trees are dead, the remaining branch scaffolding may not be strong enough to hold a crop or may create a hazardous imbalance. Branches that have lost their leaves or which still hold crispy brown leaves may look dead but still be alive. Remove any dead branches that can become projectiles during fall storms, but wait until deciduous trees are dormant in mid-winter to restructure branch scaffolding. Continue to deep irrigate trees and bushes into the fall months whenever a heat spike is predicted. 

Wait to fertilize all heat-stressed plants and trees until late August when nights will be longer and a little cooler. Deep irrigate before and after fertilization. It will be tempting to feed heat-stressed plants heavily to encourage rapid new growth but feeding at half the recommended rate for the next couple of months will encourage a slow and steady recovery. Apply low-nitrogen fertilizers on landscape plants and bushes and on summer vegetables. Give fruit and nut trees one feeding of a high-nitrogen fertilizer after harvest or in September if there was no crop left to harvest. 

             

Here in the Central Valley, summer heat spikes are becoming more frequent and lasting longer with extremely high daytime and nighttime temperatures. Regular deep, slow irrigation of mature landscape and crop-producing trees is key to keeping them in good health during heat spikes. The goal is to maintain soil moisture in root zones at a depth of 1 to 2 feet. 

We need to deep irrigate more frequently than the previously recommended once a month and deep irrigation must begin at least one day before temps are predicted to be above 95 to 100 degrees for several days.

Check soil moisture levels underneath large landscape trees and deep irrigate whenever the top 5 to 6 inches of soil is dry. That could be several times a month from June to October. Younger trees and bushes planted within the last three years also may need several soakings a month. Soaker hoses are the most efficient and effective means of delivering deep slow irrigation at the outer edges of the canopy where the feeder roots lie but small oscillating sprinklers will also work. Drip emitters are not as effective. It will take at least 3 to 4 hours of slow irrigation for water to penetrate and soak the root zone. 

Insufficient water is the most common cause of poor crop set and premature fruit and nut drop. Fruit and nut trees need regular deep irrigation to maintain consistently moist soil from bloom until harvest time. Citrus trees need sufficient water in spring to set fruit and regular deep irrigation in summer through fall in order to hold and produce good-sized, juicy fruit.

During heat spikes, monitor soil moisture levels under citrus trees and deep irrigate whenever the top three to four inches of soil has dried. Plan on irrigating citrus every 3 to 4 days during heat spikes in July and August and once a week during the warm fall months.

Cool-climate redwood trees have been heavily planted in the hot and arid Central Valley to provide dense shade. Often in spaces too small for the mature tree. As a common practice, redwood trees are thinned and lower branches are removed. The heavy branch structure on redwoods creates a cooler microclimate in the interior of the canopy and thinning and removing branches on redwoods exposes the trunk and bark to the hot rays of the sun and high temperatures.  

In July, the inner needles on redwood trees will turn brown and fall. It's a normal process referred to as redwood dieback. The fallen needles form a thick mulch that will help cool the soil for these shallow-rooted trees and also slow evaporation. Redwoods will benefit from increased deep slow irrigation in summer.

Branch tip dieback is the earliest and most visible sign of drought-stress. Even one long-lasting heat spike without sufficient irrigation can cause tip die back on any type tree. Gusty winds now often accompany heat spikes. Dead branches can become hazardous projectiles and should be trimmed off when noticed, but corrective pruning to reshape branch scaffolding should wait until deciduous trees are dormant in late fall and winter.