Gardener’s Corner

Monthly Article by Cate White,

San Joaquin County Master Gardener

(Note: Cate is taking a break during August and this information on watering is so important that it will be posted 2 months)

This year the entire western United States is facing severe drought conditions.   Not only has rainfall been scarce, but snow run-off has also been far less than expected.  Reservoirs are running low, and groundwater pumping is becoming more regulated as underground aquifers are being depleted.  Water has always been a precious resource in California, and this year it is even more so.

So, what does this mean for those of us who love to garden?  Practicing water conscious gardening doesn’t necessarily mean we are limited to growing succulents and cactus; there are many plants that have low to moderate water requirements. The University of California Cooperative Extension provides two good resources for finding appropriate plants to grow in our area.  WUCOLS (Water Use Classification of Landscape Species) offers a website that allows you to research plants name or by type (such as groundcover), giving water use needs for each.  The Arboretum All Stars web site is a listing of plants along with their water needs that thrive in our area.  Both usually have pictures and cultural information that can help you decide if a particular plant fills your needs.  The plants pictured in this column come from the All Stars site.  Another good resource is the Sunset Western Garden Book.  Many attractive options can be found using these resources

You may need to ration water, giving priority to those plants that are hardest to replace, such as trees and shrubs.  Mature trees should be able to get by with minimal watering.  Shrubs, fruit and nut trees will have slightly higher requirements.  The lowest priority should be annual flowers, herbs, and/or vegetables.  Turf less than a year old will have greater need for water than more established turf.  This year, I decided to grow fewer vegetables, letting one of my planting beds go fallow for the summer.

The following are additional tips for managing water in your yard:

  • Be familiar with your irrigation system.  Know how to set up your watering program, and review it regularly.  Check often for broken lines, misdirected sprinkler heads and faulty valves. 
  • Rotor sprinkler heads are best for lawns.  To be sure that your lawn is watered evenly, try the “tuna can test”.  Place tuna cans in strategic locations around your lawn, then run the sprinklers.  After the sprinkling cycle, check the cans to see how much water is in each one.  If the amount in each can varies greatly, adjust your sprinkler heads to get more even water distribution.
  • Try to place plants with similar watering requirements in the same watering zone.  If this is not possible, it might help to add more drip lines to thirstier plants, or use drippers with a higher water flow rating.
  • Manteca generally has sandy loam soil, which dries out more quickly than the clay soils found in most areas of California.  Use a screwdriver to measure the moisture in your soil.  It should be damp to a depth of 2 inches.
  • Early morning watering is most efficient 
  • Adding compost helps retain soil moisture.  Mulching with bark or compost to a depth of 2 to 4 inches also helps, but keep bark away from trunks of trees and shrubs to avoid rot.  Compost makes good mulch for vegetable and flowerbeds.
  • Withhold fertilizer, especially fertilizer high in nitrogen, as that stimulates growth, in turn increasing the need for water.
  • Plants in pots and raised beds will need more water than those in the ground
  • Keep beds free from water hungry weeds.

Household water can be saved in buckets or jugs and used to water plants with high water needs, such as those in pots.   I keep a bucket in my shower to collect the water I run until it is hot enough for showering.  The same thing can be done with containers by the kitchen sink.

Follow city of Manteca Water Conservation Guidelines. 

  • Residences with odd numbered addresses can water Wednesday, Friday and Sunday, while even numbered addresses may water Tuesday, Thursday and Saturday.  No watering is allowed Mondays, or within 48 hours of measurable rainfall.  Watering early in the morning avoids excess evaporation and wind drift.  The city recommends watering before 4 am or after 7 am, when water pressure is highest.
  • Watering must be done before noon or after 6 pm. 
  • Avoid run-off.  If run-off occurs, adjust your watering program.  You might try a two-phase system, programing your irrigation to run for half the total time once through, then a second time after an hour or more for the other half. 
  • Water should never be used to hose off sidewalks, driveways, or patios.

For more information about best irrigation practices, go to:, and click on Water Conservation in the Home Landscape.  Let’s hope for some good rain this coming winter!

August Garden Checklist

  • Continue checking irrigation lines and valves to be sure they are functioning correctly. Adjust timing according to weather conditions.
  • Be on the alert for mosquitoes. Eliminate all standing water. For birdbaths and ponds, control by adding Bacilus Thurengiensis israelensis or mosquito fish
  • Continue baiting for ants.
  • Check for aphids, whiteflies, caterpillars and spider mites. Use a strong spray of water on whiteflies and aphids, and mist the undersides of leaves for spider mites. Neem oil and insecticidal soaps can also be used, but only during cool parts of the day and when bees are not present. Spray Bt (bacillus thurengiensis) for caterpillars.

  • Use neem oil as described above for powdery mildew.
    • Mow lawn down by no more that 1/3 when weather is hot
    • Put out traps to control yellow jackets.
    • If you have trouble with blossom end rot on your tomatoes, (dark leathery spots on the blossom end), be sure you are applying water evenly, keeping the soil uniformly moist, neither dry nor saturated. Follow recommended fertilizer amounts. Some tomato varieties are more susceptible than others, but since this is not caused by a pathogen, there are no pesticide solutions.
    • Deep water young trees every week or two in hottest weather.

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