Low-Cost Propagation Methods Can Multiply Your Shrubs

This multi-caned red twig dogwood can be propagated by using simple layering, division, runners or stem cuttings.

In last month’s post, I explained how to use simple layering to propagate shrubs with branches close to the ground.

But what about shrubs that don’t have low-hanging branches?  Fortunately, there are other propagation approaches you can use: Dividing root balls, transplanting runners, and taking stem cuttings.  Within a short time, you can have several baby shrubs for transplanting around your yard.

Dividing root balls.  There are many shrubs that don’t respond well to division because of their tree-like growth habit from a single trunk.  But there are other shrubs, primarily those that produce multiple canes, that divide nicely.  Examples include butterfly bush, rose, dogwood, spirea, potentilla, lilac and forsythia.

To propagate by division, dig up the root ball of the mother plant.  The root ball may fall apart by itself, leaving several cane clumps with roots attached.  If not, use a shovel or knife to cut the ball apart, being careful to minimize damage.  Make sure that each cane clump has a good root ball.  Then transplant the clumps to their final resting places.

Transplanting runners.  Some shrubs produce runners, called rhizomes (underground) or stolons (above ground), which create suckers.   These shrubs are called colonizers because, over time, they’ll create colonies of themselves if left unchecked.  Colonizers include serviceberry, dogwood, lilac, sumac and kerria.

If you want to propagate and transplant a baby shrub from the mother shrub, look for a branch growing several inches from the mother plant—a branch that looks like it wants to strike out on its own.  Carefully dig around that branch to see whether it’s attached to its own runner.  If you spot a runner, dig it up, coat it with a rooting hormone, such as Clonex, and gently place it in a hole in a pot or in the ground.

If you’re using a pot, mix peat moss with sand or perlite for a loose, well-draining medium.  If you’re planting the runner in the ground, dig a trench about six inches deep and fill it with sand.  You should moisten your growing medium with water, then poke a hole in the medium with your finger so you can insert the runner into the medium without disturbing the rooting hormone.  Then gently backfill the hole.  After that, just keep the runner watered the same as you would a regular plant.

Then wait about four months or so to give the runner time to develop auxiliary roots before transplanting it to its new home.

Taking stem cuttings.  This approach, in my experience, is the diciest of the propagation methods.  So if you can propagate a shrub by layering, division or transplanting runners, I suggest that you use one of those methods instead of taking cuttings.

In spite of difficulties, I have successfully propagated red twig dogwoods from cuttings.  But my success rate was only about 60 percent. Professionals have better equipment and are far more adept at propagating from cuttings than I am.

With layering and division, I’ve had a 100-percent success rate, and with transplanting runners, I’ve averaged about 75%.

If you have your heart set on propagating a shrub that can’t be propagated with the other methods I’ve described, then cuttings are the way to go.

There are three types of woody plant cuttings:  softwood, semi-hardwood and hardwood.  Softwood cuttings are taken from tender new growth in the spring or early summer.  Semi-hardwood cuttings are taken from partially matured growth in the summer.  Hardwood cuttings are taken from mature stems during the fall and winter.

Different types of shrubs root more readily from different types of cuttings.  Daphne and euonymus, for example, propagate most readily from semi-hardwood cuttings.  Viburnum, on the other hand, propagates most readily from softwood and hardwood cuttings.

To determine which shrubs require which cutting types, I check my reference book, Plant Propagation from The American Horticultural Society.

When I propagated red twig dogwoods, I took semi-hardwood cuttings in late summer and stripped off all the leaves.  Then I dug a trench, filled it with sand, and planted the cuttings the same way I did for the runners mentioned earlier.  I then mulched the cuttings with black plastic.  The following spring, I planted the cuttings in their final resting places.  Four of my seven cuttings survived the winter and transplanting.  I used rooting hormone on three of the seven cuttings.

If you want to get serious about rooting shrubs from cuttings, I suggest consulting Plant Propagation for step-by-step instructions.


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A Plant Geek’s Haphazard Approach To Propagating Shrubs

The equipment and supplies for simple layering are simple–gloves, sand, compost, anchoring pins, rooting hormone, pruners and a spade. The mother plant, a Genista lydia, sits in back.

Have you ever wished you could get three shrubs for the price of one?  Well, you can, with a little know-how and patience.

You simply propagate new plants from the mother shrub.  There are several ways to do this, including layering, dividing, digging up runners and taking stem cuttings.

Today I’ll cover simple layering.  In a future post, I’ll review other propagation methods that you can perform in your garden.

My study of propagation began last fall when I bought Plant Propagation, an excellent reference book produced by The American Horticultural Society.  I learned about hardwood and softwood cuttings, heating pads, cell trays, rock wool and all manner of horticultural mechanisms.  And I soon realized there were all kinds of propagation equipment and supplies that I didn’t want to spend money on.  So I experimented on the cheap.

I wanted to propagate more Genista lydias from my existing genista.

This shrublet is one I started last spring from layering. So it has been in layering mode for 6 months. I’ll wait until next spring to transplant it.

First, I tried taking a genista cutting and growing it in a sand/potting soil mixture in a pot with a plastic bag over it to retain heat and moisture.  Within a week or two, tiny green buds started popping up all over the cutting.  But a few weeks later, the cutting rotted and died.

So after doing more propagation research, I decided to try simple layering.  You can perform simple layering on any shrub with branches low enough to reach the ground.  I used it successfully last fall on red meidiland ground cover roses.  So I figured it might work for Genista lydia, as well.  Other candidates for simple layering include climbing roses, spreading cotoneaster, forsythia, lilac, viburnum, daphne, raspberries and blackberries.

Here’s my approach:

Step 1.  Collect your tools and equipment.  Mine include gardening gloves, pruners, spade, anchoring pins (I had edging pins on hand, so I used those.  But you also can use smaller, less expensive landscape fabric pins), rooting hormone (such as Clonex or Garden Safe TakeRoot), compost and general purpose sand.  The Clonex set me back $20, but everything else is stuff I already had around the house.  You can make homemade rooting hormone, if you want.  Just google online for recipes.

After digging your trench, strip all leaves from the underground portion of your selected branch and scrape a thin coat of bark off of the bottom of the branch. Then anchor the branch to to soil. I took this photo before pushing the anchoring pin farther into the ground so that you could see the pin more easily.

Step 2.  Select a young branch that’s at least 10 inches long.  You’ll need to bury some of it and have enough branch left over to leave some vegetation above ground.

Step 3.  Dig a trench 4 to 5 inches deep and about 6 inches long beneath your selected branch.

Step 4.  Strip all leaves from the portion of the branch that will be buried.  Scrape a thin layer of bark off of the bottom of the branch to encourage rooting through contact between the plant tissue and the soil.  You can also apply rooting compound at this point, but I generally just wait until the transplanting phase to use it.

Step 5.  Anchor the stripped portion of the branch to the ground with one or more anchoring pins.

Once you’ve anchored your branch to the ground, cover the anchored portion with 2 to 3 inches of a 50/50 compost/sand mixture. Then backfill the remainder of the trench with soil.

Step 6.  Cover the anchored portion of the branch with 2 to 3 inches of a 50/50 compost/sand mixture.  Then backfill the remainder of the trench with soil.  I’ve found that the compost/sand mixture improves drainage and prevents rotting, which is often a problem in heavy clay soils.

Step 7.  Position the above-ground portion of the branch so that it’s as vertical as possible.  You can even stake the top, if needed.  I don’t stress out if the branch isn’t perfectly vertical because I’ll be digging it up later to transplant it anyway.  At that point, I can reposition the top as needed when I replant it.

Step 8.  Mulch the trenched area and water it regularly.  Then wait.  Depending on your growing conditions, your new shrublet may be ready for transplanting in 4 to 6 months.  I typically transplant in spring or early fall for best root growth.  I dig a hole, coat the new roots of the shrublet with rooting compound, place the shrublet in the hole, and backfill with a mixture of two-thirds soil and one-sixth each of compost and sand.

There is one caveat to propagating your own plants asexually—that is, by any method other than planting seeds.  Don’t propagate patented plants.

Here’s the deal when it comes to patents.  When a breeder introduces a new plant, the breeder applies for a patent, which is valid for 20 years.  It’s only fair that the breeder should have an opportunity to recoup its costs and make some profits for developing the new plant.  Once the patent has expired, it’s all right to homeowners like you and me to propagate the plant asexually.

So do your research online to find out whether the plant you want to propagate has a patent in force.  Otherwise, you could face severe legal penalties.


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Bury Bulbs Now for Spring Surprises

Corydalis ophiocarpa’s yellow blooms brighten the landscape in early spring.

Some things in life are just worth the wait. Take spring-blooming bulbs, for example.

In autumn, you dig a hole, gently insert a small vegetative object and cover it with soil. Then you wait. Come late winter or early spring, vibrant little beauties start poking their heads above ground, and before long you’re looking at a lavish display of pre-season blossoms–an end-of-winter announcement.

October is prime time for planting spring- and early-summer-blooming bulbs in Colorado, but you can get away with planting in early November, as well.

If you haven’t bought bulbs yet, you probably can still find some at nurseries, hardware stores and even big box stores, such as Costco.  The ones from the hardware and big box stores may not be premier quality, but they’ll get you by—especially if you just want to experiment.

Siberian squill’s nodding blooms add a woodland feel to the garden.

If you want top-quality bulbs from, say, mail-order catalogs, you’ll have to wait till late April/early May for the best selection of spring bloomers.

Why bother with bulbs?  Because they extend your growing season. Some bulbs, such as crocus and winter aconite, bloom as early as February, long before most perennials start waking up in April or May.

On top of that, bulbs are cheerful, exotic and easy to grow.  And they come in a massive variety of shapes, colors and sizes.

Allium 'Globemaster'

Globemaster allium, with its giant head that measures 6 to 8 inches across, is astonishing. It blooms in late spring or early summer.

Some of my favorites are Corydalis ophiocarpa with its ferny leaves and bright yellow flower stalks; Siberian squill with its delicate, nodding blue heads; and allium with its dramatic drumstick-like demeanor.  If you can’t find Corydalis ophiocarpa, you can find its darling cousins, such as C. solida or C. lutea.

Then, of course, there are ever-popular tulips and daffodils.

When planting bulbs, be sure to dig the hole two to three times as deep as the bulb’s height.  So if you have a tulip bulb that’s one-inch tall, for example, make your hole two to three inches deep.  Also, make sure that you insert the bulb so the pointy end faces up.  Otherwise, you’ll never see blooms.

I’ll admit that bulbs aren’t the first plants that I install in a landscape.  I want to get the trees, shrubs and perennials in place first.  But once that’s done, I like to tuck bulbs into small openings here and there in the garden.  They create such a nice surprise.

Try a few bulbs.  You’ll see what I mean.



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New Man Kick-starts Garden Corner

Mini Man viburnum requires some shade and medium moisture. Eventually, this shrub will grow 4-6 feet high and wide.

There’s a new man in my life.  No, it’s not a garden gnome; it’s Mini Man dwarf Manchurian viburnum.

He’s the cutest thing on a wood trunk.   Right now, he’s loaded with bright red berries that are beginning to turn blue-black.  His small, velvety, medium-green leaves may soon turn maroon and hang on until late autumn.  Then next spring, he’ll explode with clusters of creamy white blossoms that will persist for several weeks.

He’s currently a foot high and wide, but may reach 4-6 feet high and wide at maturity.

Red and blue-black berries adorn Mini Man viburnum in the fall.

Although some descriptions indicate that Mini Man will grow in full sun or part shade, I would definitely lean toward part shade in Colorado.  His leaves are a little sunburned right now, but by spring the dogwoods next to him will grow higher and provide more shade.

Homeboy Scott Skogerbee, chief propagator of Fort Collins Wholesale Nursery, discovered this darling by accident in 1999 while visiting a nursery in Montana.  He noticed a single compact shrub nestled in a 50-foot hedgerow of taller Manchurian viburnums (V. burejaecticum).  The little guy was identical to his taller brethren except for size.

In 2016, Plant Select announced Mini Man as one of its winners.  Plant Select is a nonprofit consortium of Colorado State University, Denver Botanic Gardens and professional horticulturists. The purpose of this collaboration is to test and select plants that will flourish in the high plains and intermountain regions.  Each year, Plant Select announces a small number of winning varieties from around the world.

For years I’ve listened to gardeners rave about their viburnums.  I’ve never grown one, though, because they usually morph into behemoths that would devour my yard.  The 15-by-12-foot Manchurian viburnum is a prime example.  So I’m delighted that Mini Man has come along.

If you’ve never tried a viburnum, you might dedicate a spot for Mini Man in your own garden.

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Hyssop—A Magnificent Must-Have for Your Garden

There are some perennials that simply scream, “Plant me in your garden!  You’ll love me!”

Hyssop (Agastache ssp.) is one of those plants.

Why is this drought-tolerant stalwart a must-have perennial?  For all kinds of reasons.

Brian, my resident hummingbird, visits my hyssop several times daily for his latest dose of nectar.

It attracts hummingbirds and other pollinators.  At 5:40 last evening, I spotted Brian, my resident hummingbird, chowing down on nectar from my sunset hyssop.  Brian visits several times a day.  A couple of days ago, Brian even brought a friend with him.  I have two clusters of three hyssops in my back yard.  If you add orange carpet hummingbird (Zauschneria garrettii) ground cover to the mix, you may entice even more hummingbirds.

It adds vibrant color to your garden for at least two months.  Hyssop delivers not only purple, orange and pink blossoms, but blue ones, as well.  My favorites are sunset hyssop (Agastache rupestris) and Sonoran sunset hyssop (Agastache cana ‘Sinning’ Sonoran Sunset).  They begin blooming around mid-July and keep supplying flowers until frost.

Hyssop adds a stunning backdrop to lower-growing plants in the garden, such as dwarf broom (Genista lydia), Pawnee Buttes sand cherry (Prunus besseyi ‘Pawnee Buttes) and blue avena grass (Helictotrichon sempervirens). The fuchsia beauty in the back left is Sonoran sunset hyssop. To its right, you’ll see the orange-and-purple sunset hyssop.

It provides dramatic sprays that act as a backdrop to lower-growing plants in the garden.  In my garden, both the sunset and Sonoran sunset hyssops grow about 42 inches tall.

It’s a long-lasting cut flower.  I never thought hyssop would be a viable cut flower because the blooms look so delicate.  But I tried it as a background for zinnias and coneflowers in a simple arrangement, and the hyssop lasted nicely for four or five days.  I typically add half a teaspoon of sugar to the vase water to help flowers stay fresh longer.

Hyssop offers a lively background to this informal arrangement of zinnias and coneflowers.

It provides fragrance.  As a member of the Lamiaceae (mint) family, hyssop imparts a pleasant, minty aroma.

It offers food and drink for people.  You can add sunset hyssop’s edible blooms to salads and fruit dishes, or mix it with cream cheese or butter to make a tasty spread, according to medical herbalist Tammi Hartung in her blog, Desert Canyon Farm Green Thoughts.  You can also use the blossoms to make herbal tea.

The only downside to hyssop is that it’s not a long-lived perennial.  I lost two of them after three years.  But the other seven that I planted at the same time are still blooming reliably.  So I’ll simply replace these lovelies as needed.


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Breathtaking New Cultivars Flourish at CSU’s Annual Flower Trial Garden

Pots, lined up with military precision, display the latest coleus, geranium, petunia and calibrachoa cultivars, as well as cultivars from other genera.

If you drive by Colorado State University’s Annual Flower Trial Garden on August 7, you’ll notice a horde of individuals, armed with clipboards and electronic devices, roaming around.  They’re green industry professionals, CSU Extension master gardeners, and university faculty, students and employees, all participating in evaluation day.

More than 1,000 annual flower cultivars await evaluation by green industry professionals, CSU faculty and employees, and CSU Extension master gardeners on August 7, 2018.  Some of the flowers are in pots, but most are in the ground.

The evaluators’ task is to rate more than 1,000 new cultivars of annuals on uniformity (whether all plants of the same variety look similar), vigor, floriferousness (number of blossoms), and tolerance to environmental and abiotic stress (sunlight, day/night temperature extremes, soil pH, clay texture, etc.).

Green Fuse Botanicals has developed a new kangaroo paw cultivar, Kanga Jump Red. It’s exciting to see kangaroo paw here in the U.S., given that it’s native to Australia.

Once the results are tabulated, the winning varieties for 2018 will be posted on the CSU Flower Trial Garden website.

Evaluation day represents the yearly culmination of trialing efforts at CSU.  In the spring, growers from around the country ship cuttings to CSU, where students, employees and master gardeners transfer them to 4” pots at CSU’s state-of-the-art greenhouses so the growing can begin.  Seed companies send their newest offerings to Denver’s Welby Gardens, where the seeds grow into small plants under controlled conditions.

In late May and early June, CSU students, employees and master gardeners transplant most of the seed- and cutting-grown plants into pre-dug holes in the ground.  The plants and planting areas are carefully labeled to ensure that the right plants end up in the right holes.  The planting area is regimented, with two rows of nine plants of each new cultivar installed next to other new cultivars of the same type and similar color.  For example, 18 red geraniums from, say, Proven Winners might be planted next to 18 red geraniums from, say, Dummen Orange.  That makes it easier for evaluators to compare one red geranium variety to another.

How luscious is this? Proven Winners has created a stunning new coleus, ColorBlaze Torchlight.

Besides planting in the ground, workers also install many of the plants in large pots with about five plants per pot.

Sometimes hail storms and other environmental events occur that can wipe out new plants.  For that reason, CSU grows backup plants and stores them in its greenhouses.

Among my favorite annuals this year are Green Fuse Botanicals’ Kanga Jump Red Anigozanthos (the beloved kangaroo paw from Australia), Proven Winners’ richly colored and highly textured ColorBlaze Torchlight Coleus, Dummen Orange’s Confetti Garden Cupcake Smarty Party Portulaca, Floranova’s Apollo Pink Cosmos, and Danziger’s Lia Mix Calibrachoa.

Dr. James Klett, CSU professor of landscape horticulture, and David Staats, department of horticulture research associate, supervise the operation of the annual trial program.

CSU’s garden is one of about 80 trial sites throughout the U.S. and Canada.  The yearly trial is operated as part of the All-America Selections program, whose purpose is to test new, unsold cultivars; inform gardeners about the winners; and instill trust in AAS winners.

Besides trialing annuals, CSU also trials perennials and cool-season plants, such as violas and pansies.

So, if you want a leg up on the latest plant varieties, visit the trial garden.  You probably won’t be able to buy your favorites right away.   But if they do well in the trials, you’ll likely find them in your local garden center within a year or two.

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What Now??? Rozanne Succumbs to Mosaic Virus

Cucumber mosaic virus, like other mosaic viruses, causes yellow mottling on the leaves and can lead to leaf distortion and plant stunting.

A couple of weeks ago while mowing my lawn, I noticed yellow splotches on the leaves of one of my robust Rozanne cranesbills.  “Looks like some kind of mosaic virus,” I thought to myself.

So I hopped on my computer and started googling away on cranesbill geranium issues.  Within minutes, I discovered that cucumber mosaic virus can attack cranesbills and that it’s often vectored by aphids.  So, I figure that an aphid probably visited the plant, sucked on it, and in the process, infected Rozanne.

Weeds apparently provide a great food and disease source for aphids, and I happen to live between the two weediest yards in the neighborhood.

The virus can also be transmitted via garden tools and gardeners’ fingers, according to The Royal Horticultural Society.  That’s why it’s important to clean tools and hands with soap and water.

Besides causing yellow mottling, cucumber mosaic virus can lead to leaf distortion and plant stunting.

It’s important to dispose of diseased plants to keep them from infecting other plants in the garden.

Worst of all, there’s no chemical control for the virus.

After reading all that, I raced outside, dug up the infected cranesbill, conducted a speedy funeral, and tossed the plant into the trash.  It broke my heart to destroy a gorgeous two-year-old cranesbill.  But it was the only thing I could do.

Next, I checked the four cranesbills surrounding the infected one.  Fortunately, I didn’t see any mottling on the other plants.

Normally, I blast a plant with water to dislodge aphids.  But in this case, I wanted to take more definitive action.  So I whipped out my Ferti-lome Triple Action insecticide/fungicide/miticide and sprayed all of my geraniums, roses and Pawnee Buttes sand cherries.  When I used Triple Action on my aphid-infested sand cherries last year, the plants recovered nicely.

I’ve been growing hardy geraniums, including Rozanne and bloody cranesbill (Geranium sanguineum), for ten years or so, and have never had any problems with them.

My online research indicates that allium can repel aphids.  Interestingly, though, I did have one allium growing near the Rozannes, and still had this mosaic problem.  Maybe I need more alliums.

Other plants that reportedly repel aphids are catnip/catmint, garlic, chives and mint.

I grow Little Trudy catmint next to my roses, and so far, haven’t spotted any aphids on the roses.  All of my roses are own-root roses.  So fortunately, I don’t need to be concerned about another virus– rose mosaic virus—on those plants because that disease attacks only grafted roses.  It’s yet one more good reason to plant own-root roses, such as those sold by High Country Roses.



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