September in the Contra Costa Garden
September Garden To Dos
Drought Tips and Practices: Drought is the New Normal.
Wait for fall rains to add new plants to your landscape. All new plantings, even native and Mediterranean drought-tolerant plants, require water until they are established. Many drought-tolerant plants are not fully established for at least 2 years. In the meantime, there are many helpful websites to help you plan a water-wise garden.
To find the water requirements of potential new plants, head over to the Waterwonk website at http://www.waterwonk.us. Waterwonk provides easy access to WUCOLS (Water Use Classification of Landscape Species), a UC-developed database of plants commonly grown in California located at http://ucanr.edu/sites/WUCOLS/.
To use the Waterwonk interface, first select your town. Then, search for plants by how much water they need, look up a specific plant to see if it’s right for your area, or just display California natives for your area. WUCOLS is an essential resource to find great, less-thirsty plants for our climate.
Rainwater is now a precious commodity and is likely to remain so for the foreseeable future. You may be surprised how much water can be captured using rain barrels and in-ground cisterns. Southern California has been at the forefront of this technology, but numerous projects in our area are going on right now. Check out this comprehensive guide by the City of San Diego: http://www.sandiego.gov/water/pdf/conservation/rainwaterguide.pdf
Here’s an easy-to-use calculator to discover how much rain you might be able to capture: http://ucanr.edu/sites/scmg/files/30178.pdf
Mulch, mulch, mulch…
It’s a year round necessity! Mulch keeps the soil temperature lower and helps retain soil moisture to make the most of the water you do provide. It also helps keep water-competing weeds under control.
- Maintain approximately 3" of mulch on all planting beds.
- Resist the temptation to mulch over 4”...it's possible to have too much! Very thick mulch decreases the flow of oxygen into the soil.
- Apply coarse-textured mulches up to 4" deep
- Fine-textured mulch packs more closely, so apply no more than 2" deep.
- When applying mulch near trees and woody shrubs, keep mulch at least 3” to 6" away from each trunk.
For more info, see the Sonoma County Master Gardener Program article: Mulch—a Gardener’s Best Friend at http://ucanr.edu/sites/scmg/Sonoma_Gardener_Articles/Mulch--a_Gardeners_Best_Friend/
Prioritize your mature trees during the drought.
- Avoid pruning, which can stimulate excessive growth, leading to higher water demands. Instead, wait until the winter dormant season. Consult a qualified arborist on what to prune when.
- Prioritize your trees. Water two times per month, several weeks apart, to a depth of 12” inches below the soil surface. Distribute water evenly to soil within the drip line. Water conifers up to 3'-5' beyond the drip line. Following is a calculator to determine how much water your tree needs each month http://www.waterwonk.us/how-much/.
- Another helpful article on drought care for trees. http://ccmg.ucanr.edu/files/219422.pdf
More drought tips:
- Sheet mulch your drought-stressed lawn. See http://ccmg.ucanr.edu/files/172352.pdf.
- Keep pollinators in mind whenever planting. They still need our help. Check out UC ANR’s Pollen Nation website at http://ucanr.edu/sites/PollenNation/ for great tips on gardening with pollinators.
- Considering using native plants? Visit the California Native Plant Society website at http://calscape.cnps.org/ to see native and native pollinator plants suitable for your area. Just click your location on the map to search.
General Garden Care:
- Adjust your irrigation. In spite of hot days, the evapotranspiration (ET) rate has plummeted, so watering time can be reduced by 25% from a month ago.
- Start fall cleanup in flowerbeds. Cut back anything that has finished blooming or is diseased.
- If you have let your lawn die, be sure to keep the weeds in check, removing them now if possible. Once the rains come these opportunistic plants will spread all over and be a bigger headache to you and your neighbors. Consider sheet mulching, an ideal method to reduce weeds and improve the soil too.
- Avoid fertilizing plants with nitrogen; this will stimulate new growth that drought-stressed root systems cannot support.
- Pick pears, late season apples, late peaches. Irrigate if rains have not started. Pick up all fallen fruit; compost if possible.
- Fertilize citrus for the last time this year.
- Plant winter vegetable seedlings: bok choy, broccoli, cabbage, chard, Chinese cabbage, cauliflower. Mulch around plants with straw or dry leaves to retain soil moisture.
- Direct seed beets, carrots, leeks, mache, onions, peas, radishes, sugar snap peas. Add mulch once the seedlings are well established.
- If you want to start lettuce or spinach, the seeds germinate best in cool soil (75° F. or lower). Depending on local conditions, your soil may be cool enough to plant this month, or you may need to wait longer. For best results, use a soil thermometer to check before planting. To improve germination rates, soak seeds in room temperature water for 24 hours. After soaking, air dry on a paper towel for a day. Then, plant the seeds or store them for up to a week in an airtight container kept in a cool place.
Flowers & Landscaping
- This is a good time to shop for Lagerstroemia spp. (crepe myrtles). Many are still blooming so you can choose flower color; plant next month for best rooting.
- Fertilize roses for the last time this year. Use a liquid fertilizer and make sure it is well watered in.
- Dig up and divide overgrown Agapanthus, daylilies, primulas, Shasta daisies, Penstemon, Iberis sempervirens.
- Purchase bulbs for fall planting: Allium, Anemone coronaria, Babiana stricta, Crocus, daffodil, Freesia, Homeria, hyacinth, Ixia, Leucojum, Lycoris, Muscari, ornamental Oxalis, Ranunculus, Scilla, Sparaxis, Tritonia, tulips, species tulips such as Tulipa clusiana or Tulipa saxatilis, Watsonia.
- Look for large firm bulbs with unbroken skin. Chill tulip, crocus and hyacinth bulbs in the refrigerator vegetable bin for planting during October or November.
- If shot hole disease was a problem on apricots during the past season, spray your trees after leaf fall but prior to rain with a Bordeaux mixture or fixed copper fungicide. Don’t use sulfur on apricots. For more info, visit the UC IPM page on shot hole disease at http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/DISEASE/shothole.html.
- If powdery mildew has been problem on your roses in prior months, spray now with a preventive mixture of 2 tsp. baking soda + 2-4 tsp. lightweight summer oil + 1 gallon of water, repeating every 7-10 days. For more info, visit the UC IPM page on powdery mildew at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7493.html.
- Check ant bait stations around home perimeter. http://www.ipm.ucdavis.edu/QT/antscard.html.
- Block pest entry by caulking cracks and crevices.
- Check yellowjacket bait stations; replenish as needed. http://www.ipm.ucdavis.edu/QT/yellowjacketscard.html.
Local Weather Information
Linked data is from the California Irrigation Management Information System (CIMIS) weather stations. Visit CIMIS web site.
Contra Costa County Stations
USDA zones range from 8-9B
Sunset zones range from 7-17
West County: Sunset 15/16/17
Average min. temp 56.6°F (*)
Average max. temp 70.3°F
Average rainfall 0.59 inches (*)
Central County: Sunset 14/15
Average min. temp 57.7°F (*)
Average max. temp 83.0°F (*)
Average rainfall 0.32 inches
East County: Sunset 14
Average min. temp 55.4°F (*)
Average max. temp 87.4°F (*)
Average rainfall 0.51 inches (*)
(Weather averages: September 2014 data from California Irrigation Management Information System (CIMIS). (*) indicates flagged, possibly inaccurate and/or missing data.)
- The name September comes from the Latin septem for seven, since this was the seventh month of the Roman calendar. The month was named during a time when the calendar year began with March, which is why its name no longer corresponds with its placement in the Julian and Gregorian calendars.
- In the northern hemisphere, the Autumn Equinox occurs and fall begins. This takes place on September 22nd or 23rd, depending on the year.