- (Public Value) UCANR: Promoting healthy people and communities
[Originally featured in the Winter 2022 Issue of UC IPM's Green Bulletin Newsletter]
Weeds can be a problem in any landscaped areas including around trees, shrubs, flower beds, or lawns and turf. As we move from cool weather to warmer temperatures, you will see winter weeds grow and become a problem in established landscape plantings. Effective control of weeds include hand-weeding, hoeing, mulching, and herbicide applications. Good management depends on early attention to where weeds are establishing and adjusting the conditions that allow them to thrive.
Managing weeds in landscape plantings
Each type of planting bed will have specific techniques that work best. In general, dense plantings will shade out most weeds. Regardless of the type of landscape bed, it's always best to control perennial weeds before planting. Herbicides are effective in many types of landscape plantings. They are most effective when integrated with cultural practices. Many of the herbicide active ingredients available for weed control in landscape plantings are only for use by pest management professionals.
Tree and shrub beds
Landscaped areas made up of trees and woody shrubs don't need as much preplant weed control as other types of beds. Control perennial weeds after planting using methods like mulching, hand pulling, and herbicide treatments. Suppress weed growth by laying down landscape fabric, then adding an inch of mulch on top to thoroughly cover the fabric. If needed, use a preemergence herbicide. Supplement with spot treatments of postemergence herbicides and hand-weeding.
Ground cover beds
Since ground cover is expected to fill the entire bed, landscape fabric is not suitable for weed suppression. Perennial weeds should be controlled before planting. If perennial grasses are encroaching, they can be controlled with selective herbicides like fluazifop, clethodim, or sethoxydim. Spot applications of glyphosate or glufosinate can be used on perennial weeds. Mulch the bed to control annual weeds until the ground cover fills the area. Some hand weeding might be needed.
Annual flower beds
As with other landscaped areas, a dense planting will shade out weeds. Annual weeds can be managed with mulches, frequent cultivation, and hand-weeding. Periodic cultivation (every 3 to 4 weeks) will suppress many weeds. Since nonselective herbicides can't be used after planting annual beds, it's easier to manage perennial weeds beforehand. If cultural methods aren't working to control perennial grasses, you can use grass-selective herbicides with clethodim or fluazifop. Check the product label to be sure that it won't harm the annual flowers in the bed.
Herbaceous perennial beds
Manage weeds in herbaceous perennial beds as you would an annual flower bed. Be sure to get rid of perennial weeds before planting since the bed will be growing for more than one season. Use landscape fabric where possible along with mulches. You might need to supplement with hand-pulling followed by preemergence herbicides. Be aware that fewer perennial plants are included as sites on herbicide labels.
Mixed plantings
A planting bed of a mix of woody and herbaceous plants is a more complex situation. Different areas of the bed might need different treatments. Post-plant herbicide choices are limited so site preparation is critical in this type of bed. Plant woody species first and control the perennial weeds. After the first two growing seasons, add the herbaceous plants. Shade the soil with close planting. Group plants within the bed based on their weed management needs.
Cool weather weeds in landscapes
Some of the most troublesome weeds in planting beds during late winter and early spring are common groundsel, oxalis, mallows, and nutsedges.
Common groundsel
Common groundsel is most prolific in cool weather, germinating from seeds this time of year. This weed produces many seeds and can rapidly infest landscape beds. It is best controlled before it flowers. Mulch is highly effective at controlling common groundsel. Young plants can be hoed out. Diquat or glyphosate-based herbicides will control common groundsel in landscape beds.
Mallows
Mallows are annual weeds that begin growing with the first rains so you may already be seeing these sprouting up in landscape beds. This plant develops a long taproot so it should be pulled when it has four or fewer true leaves. At least three inches of mulch is needed to suppress mallow. Young mallow plants might be managed with 2,4-D products, but this herbicide will injure broadleaf plants growing nearby.
Nutsedges
Purple and yellow nutsedge are perennial plants that sprout in spring from tubers. Remove these weeds as soon as possible to prevent tuber production. Tubers (sometimes referred to as “nuts” or “nutlets”) are key to nutsedge survival. Once established, nutsedge plants are difficult to control. They don't grow well in shade so dense plantings of ground cover or shrubs will suppress nutsedges. Few herbicides are effective at controlling nutsedge.
Oxalis (creeping woodsorrel and Bermuda buttercup)
While Oxalis (creeping woodsorrel) can bloom almost any time during the year, spring is a time of heavy flowering and seed formation. Buttercup oxalis sprouts in fall and is a major weed in ornamental plantings. Hand pulling can control these weeds but be aware that mowing can spread creeping woodsorrel. Landscape fabric with two to three inches of an organic mulch on top can control oxalis. There are no selective postemergence herbicides for creeping woodsorrel in ornamental plantings.
Herbicide injury
Desired plants could be injured when herbicides are used in established landscape beds. Herbicide damage symptoms vary depending on the herbicide and the plant. Symptoms can include yellowing, bleaching, distorted growth, and death of leaves. Avoid herbicide injury by following the label about the site, plant, and application rate. Granular formulations are less likely to damage plants than sprays. When using a nonselective liquid herbicide, apply on a calm day using low pressure and large droplets. Use a shielded sprayer to avoid contact with nontarget plants. If plants are injured from soil-applied herbicides, the damage is often temporary but can cause growth inhibition. Adding organic amendments and keeping the soil moist will help the herbicides to break down faster.
For more details and for information about weed management before planting a landscape bed, see Pest Notes: Weed Management in Landscapes.
/h1>/h2>/h2>/h2>/h2>/h1>/h2>/h2>/h2>/h2>/h2>/h1>Participants will receive free carrot and cilantro seed packets!
Tues, 2/7 at 6:00 p.m. – Salida Library
Wed, 2/8 at 2:30 p.m. – Patterson Library
Sat, 2/11 at 2:00 p.m. – Riverbank Library
Mon, 2/13 at 6:00 p.m. – Ceres Library
Tues, 2/14 at 6:00 p.m. – Oakdale Library
Sat, 2/18 at 2:00 p.m. – Empire Library
Wed, 2/22 at 6:00 p.m. – Turlock Library
Mon, 2/27 at 5:30 p.m. – Modesto Library
Don't see your local library on our list? Contact them to request our classes.
- Why are the leaves on my citrus trees yellow and what should I do to make them green again?
- Is it time to prune my citrus tree?
- Can I plant a new citrus tree now or should I wait until it warms up?
Learn how to plant, prune, care for, harvest, and get all your questions about citrus during our free online webinar on Tuesday, January 31, 2023, at 9:00 a.m. Maxwell Norton, Emeritus Cooperative Extension Advisor from Merced County will be teaching this class. Use the link below to register.
Date: Tuesday, January 31, 2023
Time: 9:00 am – 10:30 am.
Where: Online
Register: https://ucanr.edu/citrus/2023
Link: you'll be sent a link to log in with before the class.
Registration will close Tuesday, January 31 at 8:00 a.m.
Can't tune in live? Watch the recording the following week on our YouTube Channel.
If you live in Stanislaus County and have a question for the UC Cooperative Extension Master Gardeners, call (209) 525-6802 or fill out our online survey http://ucanr.edu/ask/ucmgstanislaus where you can also attach photos.
- Author: Skylar Peters
Will you be participating in National Seed Swap Day this year? Seed swap day will take place on Saturday, January 28th, and is a reminder that spring is soon on its way! The first official seed swap day was held on Jan. 26, 2006, in Washington, DC. It was a day when gardeners, farmers, and plant enthusiasts came together to swap seeds from their best plants.
National Seed Swap Day is a great opportunity for people to share their favorite varieties of seeds, as well as to try out new varieties that they may not have had access to before. Collecting and exchanging seeds has many benefits ranging from preserving rare, heirloom varieties to saving money on seeds. Not to mention that the exchange of seeds perpetuates and improves biodiversity and promotes the ultimate form of recycling within your local area.
All gardeners ranging from novices to horticulture experts can benefit from the long-honored practice and tradition of seed swapping.
There are a variety of ways to swap seeds. Here are some suggestions:
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Check to see if your local library has a seed library.
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Find local seed swap groups on social media.
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Have a seed swap party with friends and neighbors. Everyone can bring their excess seeds to swap.
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Support your local seed library with seed or financial donations.
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Spread awareness about seed swapping by posting on social media.
Advice to Grow by… Ask Us!
UC Master Gardener volunteers are a great resource to connect with new and experienced gardeners for your vegetable gardening needs. From seed to harvesting your crops, the UC Master Garden Program has it covered. UC Master Gardeners are available in most counties to support your home gardening questions by e-mail, telephone, or ZOOM. In addition, UC Master Gardener Program public education events allow you to ask your questions face to face.
Click here to 'Find a Program' and be directed to your local county-based program. You will be redirected to your local county website and contact information.
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- Author: Melissa G. Womack
- Author: Missy Gable
[From the UC Master Gardener Program Statewide Blog]
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:
- Remove any debris, such as mud and silt, that may have shifted and accumulated on your plants.
- If the soil is waterlogged, improve drainage by digging ditches or furrows to redirect water away from plants.
- 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.
- 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!
- 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.
- 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.
- Monitor your plants closely for signs of stress, such as wilting or discoloration, and address any issues that arise as soon as possible.
- Once dry, start to water your plants gently and gradually to help them acclimate to the new soil conditions.
Connect with us!
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/