- Author: Elinor Teague
Last season's torrential winter rains provided a much-needed relief from 20 years of drought. However, Central Valley home gardeners deal with the effects of drought every summer because, even with regular irrigation, extremely high temperatures during our long, rainless summers create drought stress conditions.
Large mature shade-producing landscape trees and bushes have been weakened by years of drought. Summer drought speeds up the normal fall process of slowing vegetative growth and also leads to smaller leaves and early leaf drop on deciduous plants. Leaves make food for trees. Trees and bushes with fewer, smaller leaves in fall have fewer stored resources and less food for next year's growth. Small, fine roots die and plants are unable to draw up and store enough water and nutrients to overwinter well and to quickly regain their vigor in spring.
Check soil moisture levels now in several places underneath large tree and bush canopies, especially those that have not received at least monthly deep irrigation during the summer months. The top few inches of soil near trees and bushes in lawn areas may be moist from sprinkler water. Sprinkler water generally only penetrates to a depth of four inches, but try to check moisture levels at least 12 inches deep using a shovel or trowel.
Deep irrigate large, mature landscape trees and bushes in early fall to a depth of 18 inches before dormancy to help them better tolerate cold or below freezing temperatures. Continue to provide monthly slow deep irrigation throughout the winter months unless rainfall from atmospheric rivers provides sufficient water to soak the soil.
Wet soil around the roots provides better insulation against cold temperatures than dry soil. During the next few weeks closely examine your and your neighbors' large trees and bushes for branch dieback to prevent damage from falling dead branches during winter storms. Winter pruning of deciduous trees and bushes should wait until after leaf fall, but dead wood can be removed at any time.
If dead branches are large or higher than 15 feet it's best to hire a certified arborist to do the work. Many large landscape trees were blown over during last year's violent windstorms. Root systems of surviving trees may have been compromised or broken from the soil from high winds. Changes in the angle of the tree trunk as it begins to tip may not be obvious.
Check the soil under canopies for evidence of root uprise with special attention to the northwest and western sides; our winter storm winds generally come from the northwest or western direction. If you see signs of tree tipping consult a certified arborist who can determine whether the tree is unsafe and should be removed before the winter storms.
Newly planted trees and large bushes should be properly staked to help them stand up to strong winds. Use strong poles and cushioned ties on the trunk and position the poles or stakes at the edge of the rootball on the northwest or west side. Most trees and bushes have a heavier side with more or bigger branches. Check that the heaviest side of the tree or bush is planted to back up to the northwest or west. Replant if necessary to correctly balance the new tree against the force of winter winds.
- Prepared by: Terry Lewis
Tasks
- Cut warm-season grasses short and over-seed with cool season grasses – annual or perennial rye or fine fescue. Better yet – let them go dormant to save water and mowing
- Check and improve drainage around plants in low areas
- Add fallen leaves, chipped trimmings, and garden debris to compost
- Remember that plants in containers or beds under covered areas may not receive adequate water from rainfall and may require supplemental irrigation in fall and winter
- Use organic mulch around permanent plants and add organic matter to the soil to prepare beds for spring planting
Pruning
- Dispose of diseased wood by discarding in the trash
Fertilizing
- Feed cool-weather plants and vegetables
- Add bulb fertilizer to planting holes before planting bulbs
Planting
- Tulip and hyacinth bulbs that have been chilled for six weeks may be planted now
- Sow wildflowers or grasses on hillsides to prevent erosion in heavy rains
- Perennials: coral bells (Heuchera)
- Bulbs, corms, tubers: Hyacinthus orientalis
- Fruits and vegetables: cabbage, peas, spinach, plant from seed
- Annuals: toadflax (Linaria maroccana), stock (Matthiola incana)
- Trees, shrubs, vines: Indian hawthorne (Rhaphiolepsis)
Enjoy now
- Annuals and perennials: stock (Matthiola) African daisy (Osteospermum)
- Fruit and vegetables: Asian pears, chard, nectarines, peas, peppers
- Trees, shrubs, vines: holly (Ilex), Chinese fringe flower (Loropetalum), Nandina
- Fall color: crape myrtle (Lagerstroemia indica), sweet gum (Liquidambar)
Things to ponder
- Do not use lime sulfur spray on apricots or walnuts
- Prepared by: Terry Lewis
Tasks
- Monitor rainfall and adjust water accordingly to keep soil moist for new plantings
- Put organic mulch around permanent plants to conserve water and prevent weeds
- Trees need to be deeply watered as they enter dormancy
- Mushrooms often appear in the lawn in the fall as growing conditions are favorable. If you do not like them, rake or pull them out and discard
Pruning
- Prune shrubs and trees to shape. Pruning junipers during cool weather prevents sunburn
- Deadhead and shape rose bushes to promote final fall bloom
Fertilizing
- Feed cool-season lawns with time-release granular fertilizer
- Fertilize flowering annuals and perennials to promote fall growth
Planting
- Continue staggered planting of cool-weather vegetables such as chard and spinach
- Perennials: agave, dianthus
- Bulbs, corms, tubers: brodiaea, crocus, freesia
- Fruits and vegetables: onions, parsley, radish
- Annuals: larkspur (Consolida), flowering kale, Primrose (Primula)
- Trees, shrubs, vines: Goldenchain tree (Laburnum), pomegranate (Punica)
Enjoy now
- Annuals and perennials: dianthus, alyssum (Lobularia)
- Fruits and vegetables: artichokes, cauliflower, figs, grapes, kale, limes
- Trees, shrubs, vines: crape myrtle, bayberry (Berberis), beautyberry (Callicarpa)
- Fall color: maidenhair (Ginkgo biloba), goldenrain tree (Koelreuteria)
Things to ponder
Store unused fertilizers and pesticides in a dry, warm place. Pesticides should be stored in a separate, locked cabinet or container
Drought tip
Postpone unnecessary fall planting until rainfall replenishes soil moisture and supplemental watering is no longer needed
- Author: Jeannette Warnert
“I'm always interested in plants with a fragrance, like rosemary,” he said.
Hemesath returned home and was working on his computer half an hour later when one of his eyes began to itch and burn. At the advice of a neighbor, he washed it out 6 or 7 times, but the burning worsened and his wife took him to the emergency room. Doctors prescribed an antibiotic ointment. The next morning, he said, his eye was swollen closed. And nearly a week later, he still didn't have clear vision in the affected eye.
The plant, Hemesath discovered, is silver spurge (Euphorbia rigida), one of dozens of drought-tolerant plants with toxic properties that are grown in California. A scenario similar to Hemesath's prompted San Diego County UC Master Gardener Francie Murphy to get the word out about toxic plants.
Murphy was trimming a stem on her pencil milk bush when sap spurted into one eye, causing stinging pain. Murphy ended up in the emergency room too.
After her experience, she and a team of Master Gardeners secured funding from the County of San Diego to develop a website and handouts to inform the community about toxic drought-tolerant plants found in many California landscapes.
Drought-tolerant plants like cacti, yucca, agaves and aloes have adaptations to protect themselves from wildlife in search of the moisture within the leaves and stems. Some have spikes or spines to ward off people and animals, other plants don't have outward signs of danger.
A key feature of the website is a database of nearly 100 plants with photos and descriptions that explain how they are unsafe and how they can be used safely in the landscape.
Fire sticks (Euphorbia tirucalli) – Sap in any form, including dry sap, is irritating and can be toxic if it gets on skin or in eyes.
Oleander (Nerium oleander) – The entire plant is toxic if ingested. The wood can be severely irritating if burned in a fire or BBQ.
California poppy (Eschscholzia californica) – The entire plant is toxic if ingested.
Milkweed (Asclepias spp.) – The entire plant of many species is toxic if ingested.
Sago palm (Cycas regoluta) – All parts of the plant are toxic to humans and pets, and the tips of leaves are surprisingly sharp.
Mexican bird of paradise (Caesalpinia spp.) – Plants, seedpods, seeds and leaves contain toxins, which can cause gastrointestinal irritation, nausea and vomiting.
Resources for more information:
- UC Master Gardener Plant Safely website, https://ucanr.edu/sites/PlantSafely/
- Drought-tolerant plants can save water, but beware of those that are toxic
Related:
Toxic Plants for Dogs, Cats and Horses
What plants are poisonous to dogs, cats and horses? How many of those plants are in your garden and your pasture? Keep your animals safe by learning to identify those plants that can be poisonous to your animals. Many of these plants we have taken for granted and never worried about it. Join MG Karen on Zoom to find out.
Saturday, November 18, 10 – 11:30 a.m.
Woodward Park Library - Zoom presentation
- Prepared by: Terry Lewis
Tasks
- Top dress warm-season lawns with well-composted manure
- Sharpen and clean tools for fall pruning
- Adjust watering schedules to reflect cooler temperatures and shorter day
Pruning
Leaf-fall is the time to start pruning — except for apricots and olives, which should have been done in August
Fertilizing
Feed cool-weather plants and vegetables to promote fall growth
Planting
This is a good time to plant landscape trees and shrubs
- Continue to plant cool-weather annuals and those that use less water such as classic Coreopsis or hybrids such as ‘Rum Punch'
- Perennials: Lantana, Penstemon ‘Margarita BOP'
- Bulbs, corms, tubers: allium, anemone, Babiana
- Fruits and vegetables: carrots, garlic, lettuce, plant from seed
- Annuals: Michaelmas Daisy (Aster novi-belgii), snapdragon (Antirrhinum), calendula, chrysanthemum paludosum
- Trees, shrubs, vines: Cotoneaster
Enjoy now
Harvest almonds, hazelnuts, walnuts and pecans when the outer hulls split open and nuts fall to the ground. Pick up nuts daily or shorten the task by shaking branches or knocking nuts down with a pole. Before shelling, dry nuts in the sun for two to three days; properly dried nutmeats should snap in two rather than bend. Use shelled nuts right away, or store in the freezer to prevent oxidation (rancidity), mold, and infestation by ants or small worms.
Fruits and vegetables: jicama, pumpkins, olives
Things to ponder
- Overnight temperatures in late October occasionally drop below freezing. Frost
protection will be needed for houseplants, citrus, avocados and other cold-sensitive
plants - Do not replace vinca with pansies in the same bed - a soil-borne fungal root rot affects these plants
Drought tip
Use drip or soaker hoses for cool-season vegetable gardens, rather than less efficient overhead or furrow irrigation
