Triple-digit temperatures and smoky conditions can create high pollutant levels
Ash collects on the leaves of a large lily plant. Debbie Arrington
Maybe consider wearing a facemask while gardening?
Ash on the leaves of plants is a reminder: With wildfire smoke comes fine particulate matter. That stuff can get in your lungs – as well as clog plant pores.
So far this wildfire season, we’ve been relatively lucky in Sacramento; our air quality has remained “moderate” to “unhealthy for sensitive people” instead of downright unhealthy for everyone.
We already have unhealthy heat; the National Weather Services issued a “heat advisory” for the Sacramento region through Wednesday night with highs of 107 to 112 degrees possible.
Triple-digit heat coupled with wildfire smoke can create another problem for plants: Ozone damage. It starts out as stippling – little dots all over large leaves. Or parts of leaves or petals may look like they were sun-bleached white or silver.
Ozone is what happens when wildfire ash and other pollutants get “cooked” by temperatures more than 100 degrees. It makes our eyes water and throats hurt. (Think of a real smoggy day.)
While ozone high up in the atmosphere is a good thing, ground-level ozone can be very bad. In Sacramento’s case, it can be created by a combination of wildfire ash and other pollutants (usually nitrogen oxides and volatile organic compounds), intensified by bright sunlight and triple-digit heat.
Ground-level ozone can prevent a plant's leaves from properly doing their job. Ozone enters the leaf's stomata and burns the leaf's tissue.
Signs of ozone damage include dark stippling and bleaching of foliage. Plants lose their vigor and stop blooming or yielding fruit. Ozone damage weakens the plant and makes it much more susceptible to pests and disease.
Some plants are more prone to ozone damage than others. Researchers at the National Park Service surveyed plants in national parks and found hundreds of species with ozone sensitivity, ranging from asters to elderberries, sycamores and yarrow. Various maple, cherry, poplar and plum trees are all on the ozone-sensitive list.
In the meantime, tackle the ash and heat with the same remedy – water. Keep plants hydrated. Wash ash and soot from leaves. And look forward to lower temperatures later this week; more normal temperatures will not only bring some relief from the heat but reduce the change of ozone damage.
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Food in My Back Yard Series
April 15: Grow culinary herbs in containers
April 8: When to plant summer vegetables
April 1: Don't be fooled by these garden myths
March 25: Fertilizer tips: How to 'feed' your vegetables for healthy growth
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March 11: Ways to win the fight against weeds
March 4: Potatoes from the garden
Feb. 25: Plant a fruit tree now -- for later
Feb. 18: How to squeeze more food into less space
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Feb. 4: Starting in seed starting
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Garden Checklist for week of April 20
Before possible showers at the end of the week, take advantage of all this nice sunshine – and get to work!
* Set out tomato, pepper and eggplant transplants.
* From seed, plant beans, beets, cantaloupes, carrots, corn, cucumbers, melons, pumpkins, radishes and squash.
* Plant onion sets.
* In the flower garden, plant seeds for asters, cosmos, celosia, marigolds, salvia, sunflowers and zinnias.
* Transplant petunias, zinnias, geraniums and other summer bloomers.
* Plant perennials and dahlia tubers for summer bloom.
* Plant summer bulbs, such as gladiolus and tuberous begonias.
* Transplant lettuce and cabbage seedlings.
* Smell orange blossoms? Feed citrus trees with a low dose of balanced fertilizer (such as 10-10-10) during bloom to help set fruit. Keep an eye out for ants.
* Apply slow-release fertilizer to the lawn.
* Thoroughly clean debris from the bottom of outdoor ponds or fountains.
* Trim dead flowers but not leaves from spring-flowering bulbs such as daffodils and tulips. Those leaves gather energy to create next year's flowers. Also, give the bulbs a fertilizer boost after bloom.
* Spring brings a flush of rapid growth, and that means your garden is really hungry. Give shrubs and trees a dose of a slow-release fertilizer. Or mulch with a 1-inch layer of compost.
* Start thinning fruit that's formed on apple and stone fruit trees -- you'll get larger fruit at harvest (and avoid limb breakage) if some is thinned now. The UC recommendation is to thin fruit when it is about 3/4 of an inch in diameter. Peaches and nectarines should be thinned to about 6 inches apart; smaller fruit such as plums and pluots can be about 4 inches apart. Apricots can be left at 3 inches apart. Apples and pears should be thinned to one fruit per cluster of flowers, 6 to 8 inches apart.
* Azaleas and camellias looking a little yellow? If leaves are turning yellow between the veins, give them a boost with chelated iron.
* Pinch chrysanthemums back to 12 inches for fall flowers. Cut old stems to the ground.
* Weed, weed, weed! Don’t let unwanted plants go to seed.
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