Mulching Perennials
Trees and Shrubs
Trees and shrubs usually have an easier time getting through the winter if they are in good shape. However, if a freeze is forecasted, one of the most important things to do is to ensure they have been watered 2-3 days prior, especially if autumn has been dry. As with perennials, mulching with fallen leaves or other mulch will help protect the roots, but do not have mulch up against the tree trunk or plant stem, which could cause rot to occur.
Wrapping trunks of young trees with blankets, towels or piping insulation will provide added protection.
Bulbs
Wait until after the first frost, then gently dig up the bulbs or tubers. Cut away any leaves and brush off as much soil as possible. Let them dry out in a cool spot for about a week. Label them so you'll remember what they are! Pack them in a breathable box, such as a cardboard box, storing the bulbs so they don't touch each other, and cover them in sawdust or shredded newspapers. Keep them in a cool, dark location that is below 45°F, but doesn't freeze.
Citrus
Citrus plants can be protected by frost cloths which allow some light and air to penetrate and can stay on plants for a few days at a time. They can also lay directly on plant foliage. If you use other type of cloth such as burlap or cotton sheets, use stakes to hold the cloth away from the plant greenery. Remove it during daytime when temperatures are above freezing and sunny, and replace it each night prior to sunset. Whatever cloth you use, make sure the cloth goes all the way to the ground to capture radiant heat from the ground. If there is mulch around the plant, rake away during the day, if above freezing and sunny, to allow the soil to warm up.
Roses
Some roses are more sensitive to cold than others. As a group, hybrid tea roses are the most vulnerable. Make sure they are watered prior to predicted freezing temperatures, protect the root zone with mulch on the soil mound. You may also wish to cover your sensitive roses with frost cloths.
Container Plants
What do do if frost damages your plants? Wait!
Frost damage occurs when the water inside the cells of a plant freeze, causing damage to the cellular walls, which harms the overall health of the plant. Frost damaged vegetation will wilt, turning brown or black, as if they have been scorched. The bark may crack, or split. In severe or prolonged periods of frost the plant can die.
If you see what appears to be frost damage, wait until late spring until all chance of frost has passed. Plants are resilient and can often recover on its own, producing new growth. Pruning what seems to be damaged branches too soon can cause significantly more trauma, even death, to a vulnerable plant that might otherwise have recovered in the spring.
Resources
- https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=22929
- https://sacmg.ucanr.edu/Frost_Protection/
- https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=45517
- http://ipm.ucanr.edu/PMG/GARDEN/ENVIRON/frostdamage.html
Denise Godbout-Avant has been a UC Cooperative Extension Master Gardener in Stanislaus County since 2020.
- Author: Jeannette E. Warnert
Gardeners who follow conventional wisdom and nursery recommendations to mix organic amendments into the soil when planting new trees or perennials in their landscapes are making a mistake, according to UC Cooperative Extension environmental horticulture experts.
“This is one of the garden myths that I'm trying to dispel,” said Jim Downer, UCCE environmental horticulture advisor in Ventura County. “We recommend residents not amend the soil when they are planting based on outcomes we have observed in research.”
Downer and Ben Faber, UCCE advisor for water, soils and subtropical crops in Ventura County, summarized this and other information about the use of organic amendments in home landscapes in a six-page publication now available for free download from the UC Agriculture and Natural Resources catalog at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=8711.
The publication says research has not shown that adding amendments to planting holes for perennial plants provides a significant advantage compared to using native backfill.
With perennial plants, the roots do not stay in the planting hole for long, so amendments would only be effective for a short time. The practice of amending the soil further harms the plant by creating an interface where the soil in the planting hole is different from the native soil.
“When that happens, roots and water don't move as well through the soil,” he said.
While there are few reasons to mix organic amendments into the soil, Downer said mulching the soil surface with uncomposted organic matter is almost always beneficial.
“If your goal is to get organic matter into the soil, we recommended topping the soil with fresh, undecomposed wood chips. It will give you microbial stimulation and suppress disease. Arthropods will slowly grab pieces of the mulch and incorporate it into the soil at a gentle rate,” he said.
The publication also provides information about various common organic amendments – such as coconut fiber, coffee grounds, horse manure, peat moss and green waste compost – with details about each product's benefits and detriments.
- Author: Heidi Aufdermaur
The Master Garden handbook defines a weed as “a plant growing where it is not wanted.” For the home gardener, a plant can become a weed when it interferes with intended use of land and water resources.
I recently purchased “Weeds of California and other Western States” a two-volume resource book. It lists over 1600 pages of plants considered weeds. As I read through this book, I see many plants listed that I would not have considered as weeds, such as the broadleaf forget-me-not. I love the look of this annual. I scattered their seeds several years ago in one area of my yard and this year I found them growing in several other places. This isn't surprising as I've observed their seeds attached to my clothes and garden gloves.
So, is it a weed if this pretty flower shows up somewhere else? According to the California Invasive Plant Council, the answer is “yes,” since this particular plant is also considered invasive. It can escape landscapes and move into natural habitats and pastures. The control of invasive plants in California costs over $82 million dollars per year.
Nostalgic Weeds
One “weed” I enjoy came from my grandmother's garden, it's called the “three-corner leek”. This “weed” looked so pretty in her yard, I brought it home many years ago. Now, I see it made itself comfortable all over the yard. This perennial bulb, with white umbel-like flowers, has “escaped cultivation as a garden ornamental”, according to the “Weeds” book. It has been somewhat easy to control, and I dig out the bulb when it appears. I think of Grandma when I see it, so in the garden, it's staying.
A Weedy Menace
I am slowly winning the fight in two areas where these weeds are located. However, under the birch trees, I have surrendered to taking my garden knife and cutting off the greens just below the surface of the ground. I know it may not be a permanent solution, but it looks good until I need to cut the greens again, in a few weeks. The “Weeds” book says this process eventually “depletes bulb energy reserves.” I have learned not to let this plant set flowers as it also reproduces itself using seeds.
I am determined to win this battle against the weeds with perseverance. Wish me luck!!! I hope to see your comments on how you are doing controlling weeds in your garden.
UC IPM Home and Landscape Pests - Weeds
http://ipm.ucanr.edu/PMG/menu.weeds.html
California Invasive Plant Council
https://www.cal-ipc.org/
Weeds of California and Other Western States, vol. 1&2, UC ANR publication 3488
http://anrcatalog.ucdavis.edu
For more information about Stanislaus Master Gardener's program and upcoming classes, sign up for the Stanislaus Sprout blog at https://ucanr.edu/blogs/StanislausSprout
A Help Desk is also available to help with other gardening questions or concerns: https://ucanr.edu/sites/stancountymg/
Heidi Aufdermaur is a graduate of the 2019 Class of Master Gardeners in Stanislaus County.
Advice for the Home Gardener from the
Help Desk of the UC Master Gardeners
Program of Contra Costa County
Master Gardeners' Help Desk Request: I recently moved into a home in Clayton and am very fortunate to have inherited many beautiful perennials! One, in particular, has stumped me and I was hoping you would be able to help me identify it. I have attached a few pictures.
Along with identifying the plant, I am also curious as to seasonal care. It is obvious the flowers are finished. It is also very large and many have fallen to the ground (the plant isn't able to support itself). Should I cut it way back, deadhead the flowers, etc.?
Growing up in the Midwest, I don't have any experience with perennials in this climate! I am enjoying reading up and learning about the plants in my new yard. I appreciate your time and help on this endeavor!
Response from the MGCC Help Desk: Thank you for contacting the UC Master Gardener Program Help Desk about your unknown perennial. Any plant identification done from a picture must be considered tentative, however, I think that this plant is a Lepechinia sp., and I suspect it is Lepechinia hastata.
Originally looking at your pictures, the plant looks like a salvia. It has broad thick leaves, with well-defined veins. However, most salvias flower on a single stalk and the flowers do not branch as you get to the top of the plant. This branching of the flowers is very prominent in your pictures as is the calyx (the cup that holds the flower on the plant). Lepechinia sp. have very similar leaves to salvias, but can have these branching flowers and a very prominent calyx.
They are in the same family as salvias and are so similar, they are frequently referred to as the false sage or the pitcher sage. There are Lepechinia sp. which are native to California but these seem to have a more drooping carriage. With the upright flowers on your plant, it likely is Lepechinia hastata, a variety that possibly was native to Mexico or Hawaii.
According to the Sunset Western Garden Book, Lepechinia sp. can grow up to 6 feet tall and wide. They require almost no summer water except under the hottest conditions and deer are rarely interested in them. It was difficult to find any clear advice about caring for this plant as it seems to require almost no care. It likes well-draining soil and does not want to be soggy.
A few nurseries recommend deadheading the plant or cutting it back after blooming so it seems reasonable to clean up the parts of your plant that have fallen down. In areas that are warm enough, it might continue to produce some flowers year-round.
Hope this helps.
Best of luck with your new garden
Help Desk of the UC Master Gardener Program of Contra Costa County (SES)
Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Biog.
- Author: Cheryl A. Wilen
Nurseries and garden centers often sell a wide range of plants for use in gardens and landscapes. As a consumer, you may manage a complex array of different landscape plantings, including woody trees and shrubs, woody ground cover beds, annual flower beds, herbaceous perennial beds, and mixed plantings. This complexity often makes weed management difficult. An integrated approach is the most economical and efficient way to control weeds, so knowing strategies for managing weeds in a variety of landscapes can help.
Woody Trees and Shrub Beds
Control perennial weeds before planting, although weed control can also be done after planting. Densely planted areas will reduce weeds. Geotextile (landscape) fabrics rather than black plastic used with a shallow layer of mulch will keep weeds from emerging. If you mulch without a geotextile base, the mulch layer must be thicker to prevent weed emergence.
If needed, you can use a preemergence herbicide to control annual weeds and supplement with hand weeding and spot applications of postemergence herbicides for weeds that are not well-controlled by hand weeding, such as perennial grasses.
Woody Ground Cover Beds
Mature, woody ground cover beds should exclude most weeds; however, when ground cover is just establishing, weed growth is likely. Perennial weeds must be controlled before planting, although perennial grasses may be selectively controlled after planting with a grass-selective herbicide like sethoxydim (Grass-Getter). Annual weeds may be controlled with mulch plus a preemergence herbicide but rooting of stolons in new plantings may be affected. You will need to supplement with some hand weeding.
Annual Flower Beds
A dense planting in annual flower beds will help shade out and compete with many weeds. Flower species should be carefully selected for weed management compatibility. Periodic cultivation at 3- to 4-week intervals and between flower beds plant rotations will also suppress weeds. Perennial weeds must be controlled before planting. Annual weeds can be controlled with mulches, preemergence herbicides, frequent cultivation, and/or hand weeding. Control perennial grasses with grass-selective herbicides like clethodim, sethoxydim, or fluazifop. Avoid nonselective herbicides in annual flower beds after planting.
Herbaceous Perennial Beds
Weed management options in herbaceous perennial beds are similar to those for annual flowers, except that it is more important to eradicate perennial weeds as there will be no opportunity to cultivate or renovate the bed for several years; and fewer species are included on herbicide labels. Geotextiles may be used in these types of plantings. Manage weeds with mulches and supplement with hand weeding. If needed, use preemergence herbicides after hand weeding.
Mixed Plantings of Woody and Herbaceous Plants
Weed management in mixed plantings is complex because of the diversity of species. Different areas of the bed could receive different weed treatments. Site preparation is critical because post-plant herbicide choices are few. Plant the woody species first and control perennial weeds in the first two growing seasons, then introduce the herbaceous species. Plant close together to shade the soil. Group plants within the bed that will receive similar weed management programs.
In most landscape situations, herbicides should not normally be needed by home gardeners. Mulching, removal by hand, and proper irrigation (pattern and amount of water) are sufficient in most cases. Find more information in the UC IPM Pest Notes: Weed Management in Landscapes.
[Originally published as "Managing Weeds in Landscapes" published in the Fall 2018 issue of the Retail Nursery and Garden Center IPM News.]
