[Originally published on the UC Master Gardener Program Statewide Blog on January 10, 2023]

A flooded backyard in Elk Grove, Calif. following exceptional amounts of rain in January. Taking steps to improve drainage and reduce water damage following flooding is crucial to the health of your plants and lawn. Photo credit: Erica Schroepfer, used with permission.

Proper irrigation and drainage are critically important for the health of plants and trees. But what happens when Mother Nature throws an atmospheric river curveball, and your yard or garden is now under water from heavy rains or floods?

Good garden soil contains a network of pore spaces filled with water and air. Both are necessary for healthy roots and beneficial soil-dwelling organisms. When the pore spaces fill with water, air is no longer available to the root system, and the roots become susceptible to root-rot organisms. Understanding the effects of flooding on plant health and caring for them after a flood event is important to saving your plants and garden.

Once the floodwaters have receded, assess the damage to your garden and begin the recovery process. There are a few things you can do to minimize the damage to your plants from flooding:

1. Remove any debris, such as mud and silt, that may have shifted and accumulated on your plants. 
   
   
2. If the soil is waterlogged, improve drainage by digging ditches or furrows to redirect water away from plants. 
   
   
3. Check the soil for compaction and loosen it up with a garden fork. This will help to improve drainage and make it easier for water and nutrients to reach the roots of your plants. 
   
   
4. Wait until the soil dries out before working with it in order to reduce additional compaction. Avoid walking on waterlogged soil to prevent compaction and further root damage. Stay off a boggy lawn!
   
   
5. Inspect your plants for damage to the roots, leaves, and stems. Remove any damaged parts, and prune your plants back to healthy growth if necessary.
   
   
6. Remove contaminated material. Consider that any garden produce touched by floodwater may be contaminated and discard it. While the risk of contamination is low in residential areas, runoff from septic systems, pastures, or industrial areas can carry potentially harmful microbes and chemicals.
   
   
7. Monitor your plants closely for signs of stress, such as wilting or discoloration, and address any issues that arise as soon as possible.
   
   
8. Once dry, start to water your plants gently and gradually to help them acclimate to the new soil conditions. 

Connect with your local UC Master Gardeners! 

Recovering from a flood can be a difficult and time-consuming process, but with proper care and attention, your garden can recover and thrive. The UC Master Gardener Program is available to help! For gardening questions and local county resources, click here to Find a Program. You will be redirected to your local county website and contact information. 

Source: Flood: Plant Stress in Extreme Wet Conditions, https://marinmg.ucanr.edu/PROBLEMS/EXTREME_CONDITIONS/Flood/

Avoid walking on waterlogged soil to prevent compaction and further root damage. Stay off a boggy lawn! Photo credit: Erica Erica Schroepfer, used with permission.

Credit: Steve Garner, Flikr.

An immense amount of rain has fallen across California in recent weeks. While rain is incredibly beneficial, in excess it can cause serious problems. The continued wet conditions opens the door for many pests, so see the list of dos and don'ts below for common wet weather pest prevention tips.

DO

• Check for snails and slugs. These critters thrive in moist environments and can often be seen on sidewalks and driveways after rain. Their feeding causes irregular holes on leaves and flowers, and they'll leave behind a slimy trail. Pesticide sprays and dusts will not be effective under such wet conditions and therefore, should not be used. Instead, hand pick them or trap them using a wooden board trap.
• Remove weeds and unwanted plants. When the ground is wet it is much easier to pull weeds and remove unwanted plants from your garden or landscape. Use this time to your advantage by catching up with any winter annual weeds, like oxalis, nutsedge, and groundsel. Be on the lookout for more in the coming weeks.
• Dump standing water. As the weather warms, any areas left with standing water will be a breeding zone for mosquitoes. This wet winter is already favoring a big mosquito season, so do your part to reduce habitat around your home. This can include dumping flowerpots and saucers, wheelbarrows or buckets, and cleaning clogged storm drains or gutters.
• Continue to conserve water. During the fall and winter months, adjust your irrigation schedule to reflect the increase in rainfall. Consider purchasing a rain sensor for your sprinkler system to avoid irrigating while it is raining. Overirrigating your plants during this time can lead to root rots and other water-borne pathogens so do what you can to reduce excess water.
• Be on the lookout for ants, cockroaches, and earwigs. These insect pests may invite themselves into your home when flooding or heavy rains make it unfavorable for them outside. Seal any cracks or openings in your home to prevent them from coming indoors. Use weatherstripping and door sweeps, and place sticky traps near entryways. Keep food sealed tightly and maintain a clutter-free environment to prevent these pests from establishing indoors.
• Remove mushrooms. Wet weather encourages the growth of above ground fruiting bodies of fungi. While not harmful to your garden or lawn, you may want to remove mushrooms to prevent children and pets from consuming them.

 DON'T

• Fertilize your garden, lawn, or outdoor potted plants. Any fertilizer applied now will likely be washed off the ground or rapidly leached out of the soil and into our waterways. Wait until the winter storms have passed and there is a stretch to time between days with rain.  
• Use pesticides (sprays, dusts, drenches). Similar to fertilizers, these products are more likely to just contaminate waterways than control any pests. Pesticides applied to foliage as sprays will be washed away quickly with daily rainfall and those applied to the soil as a systemic drench will likely not be taken up by the plant in waterlogged soils and instead will become runoff. Pesticide dusts need to remain dry to be effective, so now would not be the time to use those outdoors either.
• Prune plants. Unless necessary to remove damaged limbs or branches from the recent windstorms, avoid pruning plants under wet conditions. Pruning at this time can make plants vulnerable to pathogens and easily spread disease from one plant to another. Apricots, cherries, and olives should never be pruned during cool, wet conditions. 
• Worry about tiny piles of soil. Earthworm activity is increased during rainy weather, so if you are seeing piles of soil on top of landscape beds or the lawn, don't worry—it's just the earthworms coming out and getting some air. As they do this, they help aerate the soil. Earthworms deposit castings when they ingest soil and leaf tissue and emerge from the soil surface to remove fecal matter. Castings are rich in nutrients and organic matter and can provide some benefits to turfgrass plants.
• Compact your soil. Avoid driving or excessive walking on soft ground and keep heavy machinery off wet soils. Compacted soils make lawns, trees, and shrubs more susceptible to diseases, drought, and insects as they restrict oxygen and water from plant roots.   

For year-round actions to keep landscape plants healthy, reduce pest problems, and prevent future issues, see the Seasonal Landscape IPM Checklist to find monthly activities specific to your county or region.

Weather patterns are highly variable across the state of California. They change from year to year and across locations. While parts of the state may be experiencing drought conditions this year (Figure 1), each location can have dramatically different weather. For growers and agronomists, location-specific weather information is essential to understand plant growth and water use. It is also important for planning field management activities such as fertilization and irrigation.

Figure 1. Historical (10-year, left) and current (right) seasonal precipitation between 10/1/2020 and 1/31/2021 for California.

We have created a new interactive website where users can access their location-specific precipitation and temperature data:

http://smallgrains.ucanr.edu/General_Production/weather/

Here, users can choose a specific location and enter a date range of interest. The website uses these inputs to produce interactive graphs of precipitation and temperature patterns. The graphs show the historical (10-yr average) and current season data making it easy to compare this season to other seasons and to see changes over time.  Forecasts are also available in the main crop-growing regions of California (e.g. Figure 2). Users can also download their location-specific data for further exploration.

Figure 2. 2020-21 water year patterns for a field in Solano County where there has been ~5 in. less precipitation than the 10-year average as of the beginning of February.

That's what Bob Brendler wrote back in 1988.  Bob was the Veg Crops/Strawberry Advisor in Ventura County for 40 years and was a student of the weather.  He loved data and was the first in our office to computerize in the 70s.  Before he would crank out data on a calculator.  Literally, a big old hand crank calculator..  It went to three decimal points.

Here's his article and the results of the study he did on how cold winters had been over time. He looked at the number of days that orchard heaters were "fired" up in order to evaluate the cold for that winter.  He showed that winters since 1945 were getting warmer.  And they still are.

For years, Terry Schaeffer did frost forecasting for the Ventura area.  He knew every cold spot in the county.  We don't have that on the ground experience to tell us what to expect now, but there are still some decent forecasts out there for growers.

If you are looking for current frost forecasts, go to the California Citrus Mutual website for the Central Valley, Ventura and Desert forecasts.

https://www.cacitrusmutual.com/industry/weather-watch/

 And check out our blog on preparing for winter

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=44155