UC Master Gardeners of Monterey & Santa Cruz Counties
University of California
UC Master Gardeners of Monterey & Santa Cruz Counties

Home Gardening Tips

Care of Potted Citrus

Lemon tree
Fall and winter are the times of year when the average outdoor garden plants take a little breather, but not citrus! If your potted Meyer lemon or Bearss lime trees are like mine, they are flowering and fruiting, even as the rest of my garden rests. Thus the care of potted citrus can be a little bit different than other garden plants.

First of all, fertilize!

Citrus is a heavy feeder, particularly on nitrogen. Fertilizers are generally labeled with numeric ratios such as 3-1-1. Those numbers reflect the ratio of nitrogen (N) to phosphorus (P) to potassium (K), or N-P-K. Because citrus likes a lot of nitrogen, you want to purchase a fertilizer with at least a 2-1-1 ratio, or twice as much nitrogen as phosphorus and potassium. Citrus also requires trace minerals, which may be present in the fertilizer you purchase. If not, supplement with trace minerals such as a foliar kelp-based application. Feed according to the directions on the packaging.


According to the Four Winds Growers website, citrus can be pruned any time of year, except in the winter for outdoor trees. If you will be overwintering your citrus tree indoors, you can prune now to reduce legginess and suckering. If your trees stay outside like mine, save the pruning for spring. Visit the Four Winds Growers website for more information on pruning.


Lime harvest
Citrus prefers to be watered deeply and less frequently. Citrus likes moist, but never soggy, soil. Even if the surface of your potted citrus is dry, be sure to check the soil moisture at the roots to determine if it is time to water. A wilted tree that doesn't perk up after watering may indicate soggy roots and excessive watering. Keep an eye on leaves, too. Yellow, cupped leaves may also indicate too much water. For a potted citrus, watering deeply once to twice a week is usually adequate.

Protect from Cold Temperatures

Citrus trees vary in the amount of cold they can tolerate. Lemon and lime trees are the most cold-tolerant, probably one reason why there are so many of them around the central coast. But all varieties of citrus need some protection from frost and/or freezing. A quick and short-lived plunge in temperature won't be as damaging as a prolonged exposure to cold. If you hear that a cold front is coming, get ready:

  • Water all garden plants thoroughly before a freeze, since freezing soil will pull moisture from the plant roots
  • Put old fashioned heat producing Christmas lights on your trees or landscape lights under your trees. Be careful that the hot bulbs don't come into direct contact with leaves as the leaves may scorch.
  • Use frost cover blankets draped over your trees and attached to the ground to trap daytime heat. Be careful if using plastic covers because the trees could overheat during the day.
  • If you have the space, you could also overwinter your citrus tree indoors to avoid frost. Move the tree gradually to avoid shocking it. It's also best to let the roots get a bit dry to ease the transition and prevent the roots from staying too wet through the winter. Ensure the tree gets at least 6 hours of sun per day, or supplement with grow lights. Once danger of frost has passed, gradually move the tree back to full sun in your yard.

The gift giving season is nearly upon us. Consider a potted citrus for yourself or a loved one! They'll repay you with evergreen foliage, sweet-smelling blossoms, and tasty fruit for years to come! For much more information on citrus, visit the Four Winds Growers website. There is also an abundance of information on citrus on the UCANR website (search for citrus). And visit our earlier blog post on how to prepare your citrus for winter here. Don't forget to subscribe to our blog so that you receive an email notification when a new post goes up. If you have questions, contact us online, by phone or in person to get answers to your gardening quandaries. 


Posted on Sunday, November 19, 2017 at 9:46 AM

For the birds: California native berries that birds love

California quail. Image credit: H. Vannoy Davis © California Academy of Sciences.
People love berries and so do the birds! 

Each of these is native to California and attracts California thrashers, western bluebirds, American robins, northern flickers, Nuttall's woodpeckers, mockingbirds, cedar waxwings. scrub jays, northern flickers, yellow-rumped warblers and game birds such as wild turkey, pheasant, California quail and grouse. The blue elderberry on this list can be enjoyed by both people and birds! I have seen all of these bird species except grouse and pheasant in my yard; they are part of our area.


Holly-leaved cherry - Tall, dense shrub 

Manzanitas - Multiple species of shrubs or trees   

Toyon (Christmas berry, California holly) - Mounding form to 8 feet 

Wax myrtle - Mounding form to 30 feet 

California coffeeberry (buckthorn)Dense shrub that is easily pruned 


Blue elderberry -

Hollyleaf cherry. Image credit: Beatrice F. Howitt © California Academy of Sciences.
This is edible by humans as well. Has profuse berry clusters and grows quickly to a 15 foot tree 

California wild rose - Mounding form   

California grapes - Climber or woody ground cover 

Fuchsiaflower gooseberry - Mounding growth, has scarlet flowers and thorns 

Poison oak too! - Let the birds plant their own or control it if you prefer

Additional references:

Toyon. Image credit: J. E.(Jed) and Bonnie McClellan © California Academy of Sciences.
California Native Plants that attract birds: http://www.laspilitas.com/bird.htm

Birds and the plants they like: http://theodorepayne.org/mediawiki/index.php?title=Birds

Our own blog: Wildlife Friendly Gardens Part I and II

Don't forget to subscribe to our blog so that you receive an email notification when a new post goes up. If you have questions, contact us online, by phone or in person to get answers to your gardening quandaries! 


American Robin. Image credit: Gerald and Buff Corsi © California Academy of Sciences.


Fuchsia flowering gooseberry. Image credit: William R. Hewlett © California Academy of Sciences.
Posted on Sunday, October 15, 2017 at 9:46 AM

Wildfire Prevention and Readiness

In light of all the terrible news about wildfires this week, I would like to share some websites which can help you make your home and surroundings as safe as possible.

What you can do for you

UCANR has a Homeowner's Fire Mitigation Guide that includes a lot of information about how to fire-proof your home and surroundings. Take a look at the toolbar on the left side of the webpage. Under “Additional Information” there are several useful checklists including Quick Fixes, Pre-Fire Readiness, and a Pre-Evacuation Checklist.

This blog post has a list of UCANR fire experts (with contact info) who can answer questions related to fire prevention, impacts, and general wildfire science.

UCANR has a Center for Fire Information and Outreach. Of interest is their Fire Information Toolkit, which contains information for homeowners including a Homeowner Wildfire Assessment and after-fire resources for when it's time to go back to your property and start rebuilding.

CAL FIRE has up-to-date information on all the active fires in California. The site also has evacuation information, including video instruction for evacuation pre-planning.

What you can do for others

I read a news article that stated that the average age of fire victims so far is about 80. If you have some elderly neighbors, check in with them to see that they have the resources they need to be safe. 

I'm sure there are a lot of great organizations out there collecting donations of goods and funds to help people displaced by fire. I'll list a couple here and feel free to add more in the comments. As always, you need to make sure that an organizations values and priorities are aligned with yours before making a donation. Redwood Credit Union is collecting donations for North Bay Fire Relief. 100% of your donation goes to victims of the fires and you can designate a county for your funds or have the funds equally distributed among all the counties affected by fire. Nature's Select, a Northern California pet food company, is offering a buy one-get one deal where if you purchase a bag of dog or cat food, they will match it with a second bag. The company is delivering the pet food to families affected by fire. 



Posted on Sunday, October 15, 2017 at 9:03 AM
Tags: wildfire (1)

Pest Profiles: Fungus Gnats

Fungus gnat on a sticky trap. Photo by Jack Kelly Clark.
Fungus gnats have started making an appearance in my home. Not huge numbers, but enough to be noticeable. Fungus gnats are small flies that lay eggs in moist organic material such as potting soil or compost. They look sort of like mosquitoes and are usually between 1/8 and 1/16 of an inch long. You may mistake them for fruit flies but fruit flies look a little beefier and also are better fliers than fungus gnats. Fungus gnats are attracted to light, so you may see them near windows but they usually hang out on leaves of houseplants or on the soil in your houseplant pots. They lay eggs in the soil and the larvae burrow into the soil and feed on root hairs and other organic material in the soil. Usually they're just a nuisance in the house, but they can grow to such numbers that a plant's ability to take up water is compromised because fungus gnat larvae have destroyed the plant root hairs. Larvae may also spread plant pathogens, especially in commercial nurseries. A reproductive cycle from adult laying eggs to those eggs hatching larvae which grow to adulthood takes about 17 days and may happen more quickly when it's warm outside.

Fungus gnat larvae. Photo by Jack Kelly Clark.
There are all kinds of folk remedies for these critters. Common treatment suggestions include covering plant soil with a layer of sand or other inorganic mulch, sprinkling cinnamon on the soil surface, or even treating soil with fabric softener. But it turns out that these remedies are pretty ineffective. While mulching with inorganic material does block the gnats' ability to lay eggs on the surface of the soil, if the soil dries out and pulls away from the sides of the pot, the gnats will enter at the sides. In fact, fungus gnats have even been found to enter and lay eggs at plant pot drainage holes. So cultural remedies are unlikely to completely eliminate the problem, although emptying excess water in plant saucers and not overwatering your plants is a good start. 

If you suspect you have fungus gnats, yellow sticky traps placed on the surface of the plant soil will trap the adults. Larvae can be monitored by placing chunks of raw potato in your plants, with the cut side down on the soil. The larvae will enter the potato, at which point you can throw it away and replace it with fresh chunks.

If you determine that you have a fungus gnat problem, there are a couple of biological control agents that will control them in pots and container soil mixes. These include Steinernema nematodes, Hypoaspis predatory mites, and the biological insecticide Bacillus thuringiensis subspecies israelensis (Bti). Bti is readily available in retail nurseries so it may be the easiest agent to acquire. Bti doesn't persist or reproduce indoors, so you may have to do repeated applications at about 5 day intervals to provide control. Nematodes and mites can be mail-ordered but are live and perishable, so must be applied immediately upon receipt. Nematodes can reproduce and provide longer term control of fungus gnats. If your fungus gnats are an outdoor problem, several natural predators will help manage the population, including predatory hunter flies. Avoid broad spectrum insecticides to conserve these and other natural enemies. 

For more information, take a look at the UCANR literature on fungus gnats here and here. Don't forget to subscribe to our blog so that you receive an email notification when a new post goes up. If you have questions, contact us online, by phone or in person to get answers to your gardening quandaries!


Posted on Sunday, October 1, 2017 at 12:33 PM
Tags: fungus gnats (1), houseplants (1)

Pest Profiles: Spotted Cucumber Beetle

Last weekend I went out to my back porch to water and deadhead my container garden and came across some damage to my cosmos. The petals of most of the flowers had multiple small holes. I looked more carefully and noticed that the tomato plant next to the cosmos also had small holes in the leaves and in the fruit. Now I was curious! What was causing this damage to my plants? As I started turning over leaves and rotating tomato fruits, I spotted what looked like a yellow ladybug. A-ha! A potential pest! But who was this spotted critter?

Damage by western spotted cucumber beetle. Photo by Jack Kelly Clark.
Some time on Google netted me the moniker spotted cucumber beetle. Armed with a common name, I started looking for information on the University of California Agriculture and Natural Resources website. Pretty soon I had a scientific name, Diabrotica undecimpunctata undecimpunctata. Not just a spotted cucumber beetle, but the Western spotted cucumber beetle. Although I haven't run across this little dude in my garden before, it turns out he's the most abundant cucumber beetle in California.

As is indicated in the common name, Western spotted cucumber beetles and cucumber beetles in general are common on cucurbits, that is melons and cucumbers. But they also will feed on other tender succulent portions of garden plants, including the flowers and leaves. The life cycle includes several generations a year, with eggs laid at the base of plants or in soil cracks, larvae which burrow into the soil and eat plant roots, and adult beetles that attack the aboveground portions of plants. Adult beetles are shiny with black heads, long antennae, and yellowish bodies with black spots. There's also a related striped cucumber beetle that has stripes rather than spots, but does pretty similar damage in the garden.

Western spotted cucumber beetle. Photo by Jack Kelly Clark.
The good news: older plants can support substantial numbers of cucumber beetles without serious damage. The bad news? Although there are some predators on these critters, including a parasitic tachinid fly, predators may not be enough to dent the population, especially in commercial farming. There are no effective cultural controls for cucumber beetles. Because the larvae are underground, the only life stage that's treatable with pesticides is the adult beetle stage. For the home gardener, the best solution may be to grow seedlings under a protective cloth which can be removed when the plants are old enough to tolerate damage. 

For more information, check out the UCANR Integrated Pest Management information here and here. Don't forget to subscribe to our blog so that you receive an email notification when a new post goes up. If you have questions, contact us online, by phone or in person to get answers to your gardening quandaries!

Posted on Monday, September 18, 2017 at 3:23 PM

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