- Author: Tom Schrader, UCCE Master Gardener
Winter is here. Put your garden to bed for winter and prepare your garden for the dropping temperatures and wet season. Here are tips from the University of California Cooperative Extension Master Gardeners.
General Tasks
Compost: Turn compost and keep it as moist as a wrung-out sponge. Cover compost during the rainy weather to prevent it from becoming waterlogged.
Drainage: Correct any problems in low or poorly drained areas in the landscape.
Frost: Watch for frost warnings and protect sensitive plants. Light frost 32-29 degrees F, medium frost 28-25 degrees F, heavy frost 24 degrees F and below for four-plus hours.
Irrigation: Reduce irrigation or turn it off completely if rainfall is adequate.
Maintenance: Inventory all sprays and pesticides; take outdated or unneeded chemicals to a hazardous waste center.
Mulch: Add mulch to garden beds where bulbs are planted, and to areas where weeds have been removed.
Soil: Prevent compaction and poor aeration of soil by avoiding working, walking on, or using heavy equipment on wet soil.
Tools: Clean and sharpen dull blades, lubricate garden tools and repair damaged grips. Cleaning can be done with soapy water and a wire brush or steel wool; air dry and apply a light coat of oil to prevent corrosion. Tools with wood handles can be sanded and rubbed down with linseed oil. File cutting tools, including shovel blades, to sharpen. Store tools in a dry, covered area. Have your lawn mower serviced to get a jump on spring tasks.
Weeds: Inspect lawn and manage rainy season weeds before they flower, using nonchemical methods such as cultivation, hand weeding, or mowing; use toxic chemicals as a last resort. Destroy all roots and underground parts.
Edibles
Clean-up: Control over wintering pests by removing fruit mummies and fallen leaves on the ground from fruit and nut
trees, especially if codling moth has been a problem. Dispose in green recycle bin. Composting this material could reintroduce pests/pathogens to your garden.
Feed Plants: Fertilize citrus trees in January/February just prior to bloom.
Plan: Plan your summer garden and order seeds early.
Plant: Bare root deciduous trees, shrubs and vines, for example cane berries, fruits and nuts, grapes, and perennial vegetables. For planting, care and maintenance tips see:
Berries and Vines - https://cagardenweb.ucanr.edu/Berries/
Fruit Trees - https://homeorchard.ucanr.edu/Fruits_&_Nuts/
Propagate: During the cool season, winter, and spring vegetables should be started indoors 6-8 weeks before planting out (in December and early January). Some can be direct sown. Warm season summer vegetables should be started indoors 8-10 weeks before setting out (late Jan-Feb). Optimum soil temperature for transplanting is 55-60°F.
Protect: Watch for frost warnings. If a frost is predicted, protect citrus, sub-tropical and tender plants. Pull the mulch away from trees and water well, keeping the root zone moist but not soggy. If not already done in November, cover trees sensitive to frost.
Prune: If not done in November, prune deciduous fruit and nut trees, such as apple, pear, and stone fruits. Prune grapes and cane berries now; it's too late once they have leafed out. Note: apricot and cherry trees are the exception;
prune these in July and August only.
Landscape
Clean-up: Do a general clean-up of the landscape on a dry day; avoid walking on wet soils.
Plan: Select blooming azaleas, camellias and rhododendrons while you can see their color. Order summer blooming bulbs to plant out in early spring.
Plant: Plant container ornamental trees, plants and shrubs except subtropical plants. These include frost tolerant
perennials; hardy spring blooming annuals; summer blooming bulbs; bare root deciduous trees, shrubs and vines (like roses); seedlings of cedar, fir, pine and spruce. Scatter wildflower seed if this was not done in November. Plant azaleas,
camellias and rhododendrons.
Propagate: Start frost tender perennials and warm season annuals.
Protect: If a frost is predicted, water your plants, keeping the root zone moist but not soggy. Cover frost-tender species
as appropriate (bougainvillea, hibiscus and succulents).
Prune: Prune winter flowering shrubs just after bloom; woody shrubs and evergreen trees; hardy deciduous trees;
dormant shade trees; summer blooming vines; hydrangeas and summer-blooming perennials. Roses should be pruned
by mid-February. Wait to prune spring flowering trees and shrubs until after they bloom.
- Author: Birgitte Elbeck, UCCE Master Gardener
Starting a compost pile in winter may not be at the top of your to-do list, but it may be just the thing you need to beat the winter doldrums. Your reward will be soil that is more fertile, supporting bigger and heather plants in next summer's garden.
Types of composting: There are two primary ways to compost in the garden. There is the slow ‘cold' method, where you keep piling material in a heap and leave it largely unattended, probably for longer than a year. Then there is the fast ‘hot' method, which is what Master Gardeners recommend. This fast method not only gives you finished compost in 4-6 weeks but also ensures more consistent results and is more likely to kill weed seeds & pathogens. You do not need to run out and buy anything - however, it does require a bit of elbow grease.
Building your ‘hot' pile: Composting relies on the work of many bacteria, fungi, and invertebrates that consume and break down plant matter. They need oxygen to stay alive. This means that your pile must stay fluffy and have air pockets throughout. In addition to air, the micro organisms also need a certain amount of heat to thrive. Together, these two factors mean that a pile should not be so big that the bottom layers are crushed by the weight above, and a pile should not be so small that too much heat from the organisms escapes. Experience shows that a starting pile 3' x 3' x 3' in size will have about the proper proportions. Your pile should be placed directly on the soil and kept in place with a simple ring of fencing material or a similar enclosure. Plastic enclosures are discouraged because the airflow is restricted.
Because you will want the finished compost to provide a well-balanced set of nutrients for your plants, the nutrients in the source material must also be in reasonable balance. The focus specifically is on balancing nitrogen and carbon. For the most part, nitrogen-rich components are green (spinach, for example), and carbon-rich components are brown (wood chips, for example). Click here for additional information about “greens and browns”. Be sure to chop larger pieces to 6” or shorter, as they will compost much faster. Layer several inches of ‘greens' alternating with several inches of ‘browns.' Note that no meat, dairy, or oil should be added to the pile, nor should diseased plant materials or noxious plants with seeds be included.
Pay attention to the water content of your pile. The micro organisms require moist, but not soggy, conditions, and you can achieve this by spraying water on the pile while turning or by placing a cover over it when significant rain is in the forecast.
Turning your pile: Once you have built your pile, wait a number of days for the micro organisms and invertebrates to settle in. Some critters will already be in the raw materials, others will travel up from the soil below, and their activity will start warming the pile. Your active pile will start shrinking, and you can stick your hand toward the pile's center to get a rough feel for the heat level. The desired temperature range is 130 - 160 degrees F; you should turn the pile in that temperature range after about three days. If the pile isn't heating up, it could be that you have not reached a critical mass of materials, or there isn't enough green to go with the brown, or the pile is too green and soggy and needs more browns. Turning your pile with a garden fork onto an adjacent area gives you an opportunity to move the less digested plant materials at the edges toward the middle of the new pile, add water, and introduce new air pockets. A well-managed pile will need to be turned at least once a week, will stay hot for 2 or 3 weeks, and then cool and be recolonized by worms and other soil organisms. In 4-6 weeks, you will have finished compost that can be used to enrich your soil.
Using your compost: Your compost is ready to be spread on your garden beds when it has a crumbly texture with no recognizable bits of vegetation remaining. It will have a fresh, earthy smell. Compost does not need to be worked into the soil; the worms will take care of that for you… But if you are turning your soil, this is a good time to add it.
Links: We encourage you to look at the links to the online material below. The YouTube videos are all very short and practical, while the material on the Master Gardeners' composting page has more technical information.
UC Master Gardeners of Humboldt & Del Norte Counties composting page: https://ucanr.edu/sites/hdnmastergardeners/Resources_for_Home_Gardeners/Composting/
Demonstration videos from the Orange County Master Gardener Program:
What is Composting – https://youtu.be/8Hzz56vV9Mw
How to start a compost pile – https://youtu.be/Z2fIY7eN8fI
How to turn a compost pile – https://youtu.be/lkGRsPm-gt4
What is Hot Method? What is Cold Method? – https://youtu.be/PRpc7o_AaUc
Why are these bugs in my compost pile? - https://youtu.be/VAyM9BjEv9I
Cornell Waste Management Institute, Composting: Balancing Your Greens and Browns https://cwmi.css.cornell.edu/balancing.pdf
I Can Name That Worm in Four Clues – How About You?
Match the clue to the Worm's Image. Place an X in the appropriate column.
Worm 'A'—Earthworm, nightcrawler, Lumbricus terrestris, is one of over 2,700 varieties of earthworms. They play an important part in the ecosystem, improving the quality of the soil, such as its moisture, ability to hold water, and nutrient content. They are also an important part of composting.
Worm ‘B' – Is a jumping worm, Amynthas agrestis. It is an invasive earthworm capable of harming native forests. This pest devours leaf litter and other organic matter, changing soil texture and nutrient availability to a point where some plants may be unable to survive. Its feeding can lead to a decline in the diversity and population of native plants and other organisms within forests and gardens. If you have seen this worm, go to https://ucanr.edu/sites/hdnmastergardeners/Jumping_Worm/ to report your findings and to learn more.
Resources and Further Reading:
Cornell Cooperative Extension https://warren.cce.cornell.edu/gardening-landscape/warren-county-master-gardener-articles/invasive-asian-jumping-earthworms
UC Statewide Integrated Pest Management https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=56929
University of Minnesota https://jwp.cfans.umn.edu/meet-jumping-worm
Answers:
- Author: June Walsh, UCCE Master Gardener, Co-Curator, Moss Family Temperate Woodland Garden
From the cold, rainy day in March 2008 when we planted the 28 Magnolia denudata tree Allée in the Moss Family Temperate Woodland Garden, we knew that winter would hold special promise for this garden. Over the next 8 years, we have added many winter flowering trees, shrubs, and herbaceous plants.
Two spectacular Camellia species offer hybrids that give us the huge flowers of Camellia reticulata and the diminutive blooms of Camellia sasanqua. Camellia sasanqua ‘Brooksie Anderson' shows off lovely, small, clear pink blossoms all along its arching branches from November through January. From January through April, Camellia reticulata ‘Buddha' is covered with 6” wide deep-orchid pink flowers, some of which will mature into hard plum-sized fruits bearing three coffee bean-like seeds.
We also have Camellia sinensis (Thea sinensis), the most widely grown camellia in the world, the plant from which all true tea is derived. Don't look for bold flowers but appreciate this plant as you have a hot cup of tea on a winter morning.
In February, our most glorious Magnolia ‘Caerhay's Belle' will burst forth with 12” lipstick pink, scented blooms on naked branches. As my husband Tim says, “The great thing about ‘Caerhay's Belle' is that it blooms in February to give us a bright lift on a winter day. And the sad thing about ‘Caerhay's Belle' is that it blooms in February when the wind and rain can strip the flowers off overnight!” It tends to keep blooming for several weeks, so rainy, windy days won't rob it of all its blossoms.
Next will bloom the Allée of 28 Magnolia denudata beginning in March. The Chinese have cultivated this tree since at least 600AD and call it Yulan. Magnolia denudata, like many Asian magnolias, is a precocious bloomer, meaning that the flowers appear before the leaves, creating a very dramatic scene in late winter to early spring. If our winter is very mild, the flowers and leaves come at the same time, somewhat reducing the effect of clouds of lemon-scented white flowers.
We have had to wait a few years to see Magnolia rostrata bloom. It was planted in 2012 as a gift from the Rhododendron Species Botanical Garden. In the Spring of 2023, it rewarded visitors and volunteers with several very large fragrant flowers. It is endangered in its native Southern China and the Republic of the Union of Myanmar and seldom grown in public gardens.
Not to be missed are the early flowering and fragrant Rhododendron taronense and Rhododendron ‘Forsterianum.' Both have waxy white flowers that hold up well to rain and scent the air with dianthus and clove perfume. These plants are part of our collection of Maddenii series rhododendrons, which have been sourced and gifted by the Rhododendron Species Botanical Garden in Federal Way, Washington, where they must be grown in the Rutherford Conservatory and in cool greenhouses. Here in coastal Northern California, we can grow them outside exceptionally well.
Beginning in March, come see our Toona sinensis, Chinese Toon tree, with its brilliant flamingo-pink new growth. The green form of this tree is widely grown in Asia from the Korean peninsula, through China to Indonesia and is used for food and timber. We like our tree's amazing pink plumage in contrast to the green.
Along the perpetually wet central bed, you will find several species of Primula (primroses). Follow the stairs into the forest to see the Hellebores that the family of Stan Baird, Ph.D., donated.
Make a date to come walk through Humboldt Botanical Garden on a winter day to see the runnels awash with rainwater along the Dedekam Ornamental Terrace, then into the Lost Coast Brewery Native Plant Garden, where volunteer Curator Mark Moore has added many new native plants to the collection. Then wander up to the Moss Family Temperate Woodland Garden either from the lower Water Fall Trail or the main road. Winter is a wonderful time to visit.
June and Tim Walsh are Charter members of Humboldt Botanical Garden and UCCE Master Gardeners. June is the leader of the Tuesday Wild Weeders and Grateful Deadheaders volunteers who care for this slice of heaven.
All photos were taken by the author, June Walsh, and used with permission.
- Author: Annie Sicotte, UCCE Master Gardener
The Humboldt Master Gardener/Del Norte Help Desk is staffed by volunteers trained by the University of California to answer gardeners' questions using information based on scientific research. Click on this link to submit your garden/landscape question to our Help Desk.
Q. I have a Meyer lemon tree that has been covered with fruit for months, but not all of them are turning yellow. The fruit looks to be mature size, but some are still dark green. Recently, my tree has started to bloom again. Is this normal? Can I harvest the lemons even if they have not turned yellow?
A. One great thing about Meyer Lemon is that it can bear fruit all year round. Lemons will flower and fruit more than once per year if conditions are favorable. On the coast, Meyer Lemons often have blooms and fruit in varying stages throughout the year.
Meyer lemons are typically ready to harvest when they have turned a deep yellow or orange color and feel firm to the touch with just a slight “give.” They should also be fragrant. It's best to harvest them when they are fully ripe for the best flavor. The heaviest harvest is usually late Winter/Spring.
The reason your fruit has not turned yellow may be that we have not had enough cold weather to encourage the color change. It occurs naturally as the fruit ripens, but cold weather speeds up the process.Citrus turns color in Fall, but the color does not affect the sweetness of the fruit.
The Meyer lemon is a cross between an orange and a lemon and is known for its milder taste, so if you pick it green, it will be more acidic in taste than your typical Meyer lemon, and you may be disappointed. The fruit is usable at any stage past dark green but will have a stronger acid flavor if you pick it before it is fully ripe. Meyer lemons don't ripen any further once picked, so if it's the milder taste you want, then it's best to leave the fruit on the tree as long as possible. That said, when citrus fruit freezes, it can become pithy and lose its juiciness. Protect your tree and the ripening fruit by covering it with a blanket, heavy tarp, or row cover on those nights when it's predicted to dip below freezing.
The best place to store the fruit is on the tree. Once you pick the fruit, it does not increase in sweetness or ripen more fully. However, if you do pick the fruit, it will keep for about 4 to 6 weeks under refrigeration. Juice from lemons can be frozen for up to 4 months.
For more information on growing citrus and frost protection, check out
The University of California book, The California Backyard Orchard, or on the web https://homeorchard.ucanr.edu/Fruits_&_Nuts/Citrus/
https://sonomamg.ucanr.edu/Food_Gardening/FRUITS/Meyer_Lemon/