Do you have a gardening question? The Master Gardeners of Santa Clara County can help. Our volunteers are part of the University of California’s Cooperative Extension program and we are trained to use research-based information to educate our fellow residents on sustainable gardening and landscaping practices specifically for our area.
Our monthly "Ask a Master Gardener" column will answer your questions and offer tips. Have a question? Email lifestyle@embarcaderopublishing.com or leave a comment at the end of this month's column.
When and how should I prune my fruit trees?
The optimal time to prune most deciduous fruit trees (except apricot and cherry) is right now – January and into the middle of February. This is when most fruit trees are dormant, and since leaves have dropped, you can easily see the structure of the tree and make decisions on where to cut.
Why prune? Pruning is important in controlling the size of your trees so you can easily pick fruit come harvest time. It also lets you regulate the quality and amount of fruit you grow and keeps the tree healthy and strong.
It’s helpful to know where the fruit flowers on your variety of tree. That way, you won’t inadvertently cut off the branches where blossoms will grow. Table 1 in this document describes the location of fruiting buds in a variety of trees.
Once you’re ready to start pruning, remove dead, broken and diseased branches, and any old leaves or fruit. Remove any branches that horizontally cross other branches and may rub against them. Then make cuts to produce desired height and shape and allow sunlight into the center of the tree. That’s important, because branches exposed to sun produce the largest fruit, while shaded branches eventually stop fruiting. Help bring the sunlight in by trimming the top of the tree and by thinning out some of the interior branches. Remove water sprouts — vigorous vertical growth in the center of the tree — and the suckers that grow from the rootstock at the base of the tree. Always use sharp pruning tools, preferably disinfected with a 10% bleach solution to prevent spreading possible infections.
Successful pruning takes knowledge and experience, but we can help. Watch this video, which provides the basics for fruit tree pruning. We also are offering in-person and online classes this month. You can find the classes here, on our events page.
The University of California has published several documents that provide in-depth instruction on which branches to cut, where to cut and how to shape the tree for maximum fruit production. This one from the California Backyard Orchard offers information about systems of pruning and includes information on pruning mature, neglected trees. Another resource, Fruit trees: Training and Pruning Deciduous Trees provides detailed information and diagrams to help with successful pruning.
A note about apricot and cherry trees: Don’t prune apricot and cherry trees in the winter. They are susceptible to Eutypa dieback, a serious fungus that can eventually kill a tree. Instead, apricots and cherries should be pruned in late summer to allow pruning cuts to harden before winter rain and wind spread the Eutypa spores into pruning wounds.
What’s going on with rose care this time of year?
The winter months can be busy ones for rose gardeners. It’s the ideal time for both pruning existing roses as well as adding new ones to the garden. Here are some pruning and planting tips as well as more information on rose care in Santa Clara County.
Pruning
In our area, January is generally the best time to prune roses, even if they are not completely dormant.
The old advice was to cut the canes down drastically, but that isn’t necessary in our climate. Instead, cut back about one-third to one-half of the total height. In other words, take a 4-foot bush down to about 2-3 feet. Always make pruning cuts at an angle about ¼ inch above a bud that points toward the outside of the plant. The angle should slope away from the bud. A cut made in this location will heal rapidly and water will drain away from the bud.
Improve air flow by taking out any branches that are crossing or growing toward the middle of the plant. Move soil away from the trunk to expose suckers that are connected to the trunk and remove them; just clipping them off where you see them emerge from the soil isn’t effective. Remove spindly canes or those smaller in diameter than the size of a pencil. Clean up old leaves on the plant and ground to reduce rust and black spot.
If you’re new to pruning roses, the San Jose Heritage Rose Garden offers free pruning instruction on Saturdays from 8:30 to 11:30 a.m..
Selecting new roses
January and February are also great times to plant new roses. Nurseries and online sites are carrying bare-root roses this time of year, giving you the best selection and price. Before heading out to shop, think about where you want to plant the roses. They need six to eight hours of daily sunlight, well-drained soil, and good air circulation. Color of the blossoms and size of the plant are also considerations when choosing which rose varieties to plant.
You may also consider the balance between scent and appearance. Many of the older roses are highly fragrant, while many newer roses are bread for beauty and large blooms. You might be able to find in-ground examples of the roses you want by visiting local rose gardens. The San Jose Municipal Rose Garden has mainly modern roses. The San Jose Heritage Rose Garden has old and rare roses that are, generally, harder to find.
Once at the nursery, look for plants with plump canes, good green color, white interiors and are disease resistant. Also check their assigned grade. Bare-root roses are graded either grade No. 1, No. 1 ½ or No. 2, according to their productivity and growth and size once they bloom, with No. 1 being the best plant. While all grades will eventually grow to the same size for the variety of rose, it will take longer for the lower grades as they start with fewer, smaller canes. Here’s more information on how to select bare-root roses.
January Tips
Is my citrus ripe?
There’s a simple way to know whether your citrus fruit is ripe: taste it! Different varieties ripen at different times and harvest dates also depend on the climate or microclimate. Taste the fruit periodically to see if its suitable to you. The best place to store the fruit is on the tree because once you pick it, it does not increase in sweetness or ripen more fully. Picked fruit will keep four to six weeks in the refrigerator. Here’s more information on harvesting and storing citrus.
Mushrooms in your lawn?
If you’ve noticed mushrooms growing in your lawn, know that most are harmless and even beneficial. They decompose organic matter and release nutrients that help with plant growth. They may have developed because of overwatering or poor drainage, or because of buried scraps of construction lumber or dead tree roots. Although usually harmless, you may want to get rid of them if children and pets play in the area. Consult UC’s Mushrooms and Other Nuisance Fungi in Lawns document on ways to identify and eliminate lawn mushrooms. If cultivating or harvesting mushrooms to eat, be absolutely certain that you know it is not a poisonous variety.
Do you want to ask a UC Master Gardener about a plant problem? Submit questions to our Help Desk via email. Find garden events and classes here.
You can also subscribe to our monthly Tips and Events newsletter and to our seasonal Thyme to Garden blog.
San Mateo residents can also find gardening advice on the UC Master Gardeners of San Mateo and San Francisco website.
Find archived columns here:
• Tired of poinsettias? Try these festive plants for your Christmas decorations
• What you need to know about planting bare-root fruit trees
• Now that fall is here, what should I plant?
• What happened to my bougainvillea plant?
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