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Genetic Regression
What is going on with this unusual shrub?
By Chris Leinster - September 10, 2025
The accompanying photo perfectly demonstrates an example of Genetic Regression. Genetic Regression occurs when a genetic mutation of a hybridized plant “regresses” back to it’s ancestral form. In this instance, a Dwarf Alberta Spruce, which itself is a genetic mutation of a White Spruce, regressed back to its original form!
All Dwarf Alberta Spruce are clones of mutated branches, often called “witches brooms”, originally found growing in an isolated stand of White Spruce in Alberta, Canada. Botanists took cuttings of the mutated branches, grafted them to a common Spruce root stock, and propagated the miniature, slow-growing, conical ornamental shrubs we now enjoy as Dwarf Alberta Spruce.
For reasons that are not fully understood, and reasons that are irrelevant for this discussion, select cells at the top of this shrub reverted back to the parent White Spruce heritage. While this looks kind of cool, it is usually undesirable. The White Spruce is growing much faster and larger than intended by the design requirements and will continue to do so until it overtakes and eventually kills the host Dwarf Spruce.
Genetic Regression is quite common in many types of variegated plants, plants hybridized and selected for variable or striated colors in the leaves. For example, Emerald Gaiety and Emerald ‘n Gold Euonymus have been selected because they have white and gold margins around a green leaf. Often times, a branch or several branches will regress, displaying only green leaves, usually with more aggressive growth. Ivory Halo Dogwood, Tricolor Beech, and Purple Smoketree are susceptible to regression as well.
The remedy is quite simple. Simply prune or trim off the affected branches as soon as the anomaly is detected. Easy! The sooner the better, as the abnormality can swiftly take over and wreck the integrity of the desired traits of the plant, as the cover photo can attest.
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All Dwarf Alberta Spruce are clones of mutated branches, often called “witches brooms”, originally found growing in an isolated stand of White Spruce in Alberta, Canada. Botanists took cuttings of the mutated branches, grafted them to a common Spruce root stock, and propagated the miniature, slow-growing, conical ornamental shrubs we now enjoy as Dwarf Alberta Spruce.
For reasons that are not fully understood, and reasons that are irrelevant for this discussion, select cells at the top of this shrub reverted back to the parent White Spruce heritage. While this looks kind of cool, it is usually undesirable. The White Spruce is growing much faster and larger than intended by the design requirements and will continue to do so until it overtakes and eventually kills the host Dwarf Spruce.
Genetic Regression is quite common in many types of variegated plants, plants hybridized and selected for variable or striated colors in the leaves. For example, Emerald Gaiety and Emerald ‘n Gold Euonymus have been selected because they have white and gold margins around a green leaf. Often times, a branch or several branches will regress, displaying only green leaves, usually with more aggressive growth. Ivory Halo Dogwood, Tricolor Beech, and Purple Smoketree are susceptible to regression as well.
The remedy is quite simple. Simply prune or trim off the affected branches as soon as the anomaly is detected. Easy! The sooner the better, as the abnormality can swiftly take over and wreck the integrity of the desired traits of the plant, as the cover photo can attest.
Colorado Native Quaking Aspen
Native! So a great choice for my yard, right?
By Chris Leinster - August 11, 2025
Head west to any High Country destination in Colorado and you’ll surely pass through or arrive at a magical forest of Aspen trees. With their towering bleached white trunks, densely packed stands, and trembling leaves that flutter in the breeze, a walk through an Aspen forest is a truly enchanting experience! Spend enough time lingering among these quaking giants and you will likely encounter deer, elk, or moose that feast voraciously on the tender leaves.
As you cruise west on I-70 you may notice that south facing hillsides on your right are rather barren, hosting mostly grasses and the stray Ponderosa Pine, Pinion Pine, or Rocky Mountain Juniper. To your left, slopes are more lushly decorated with Spruce, Fir, and Aspen…lots and lots of Aspen! North facing slopes shade themselves, so they tend to be cooler and they retain more water. This is where Aspen thrive, particularly along valley floors along stream banks where soil moisture and humidity are abundant.
So they grow well in Colorado and therefore should be an excellent addition to our yard in the Front Range, right? Not so much. As previously mentioned, they prefer higher elevations and cooler temperatures. East of the Hogback the sun bakes barren soil, much like the south facing slopes of our mountain passes where Aspen are rarely found. Even with ample irrigation, the dry air of Eastern Colorado stresses Aspen through the long, hot days of Summer. I like to say that I love Aspen…in Aspen. Down here they struggle, and weak trees become susceptible to various bacterial diseases and leaf blights.
As you gaze upon a grove of Aspen Trees in the mountains, you are likely looking at a single Aspen tree with multiple trunks! Did you know that Aspen colonize by sending up trees from sprawling root systems? Technically a single tree even though you see dozens or even hundreds of seemingly independent trees. In fact, an Aspen grove spanning over one hundred acres in Utah, named “The Pando Tree”, is considered the largest single living organism on earth!
This information is useful on trivia night, but it also means that Aspen often send up trees in your lawn, gardens, your neighbor’s lawn, and generally anywhere you didn’t intend to plant a tree. The surface roots can tear up your grass, much like their close cousins the Cottonwood. And like Cottonwood, they have cottony seeds that can clutter up the garden and can also sprout trees. These attributes make them less than desirable trees for most residential gardens along the Front Range.
Even if you can get them to grow successfully, Aspen tend to be short lived down here, usually expiring within 15-20 years. I see Aspen in various stages of decline whenever I drive through a mature neighborhood. Still, if you need a quick screen and intend to be in the house for only a few years Aspen might be suitable for your needs. I don’t feature Aspen on my website so if you insist on Aspen call or email for availability and pricing. The best way to appreciate Aspen is by blasting turns on a powder day through a north facing Aspen glade at Steamboat, Beaver Creek, or, naturally, Aspen!
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As you cruise west on I-70 you may notice that south facing hillsides on your right are rather barren, hosting mostly grasses and the stray Ponderosa Pine, Pinion Pine, or Rocky Mountain Juniper. To your left, slopes are more lushly decorated with Spruce, Fir, and Aspen…lots and lots of Aspen! North facing slopes shade themselves, so they tend to be cooler and they retain more water. This is where Aspen thrive, particularly along valley floors along stream banks where soil moisture and humidity are abundant.
So they grow well in Colorado and therefore should be an excellent addition to our yard in the Front Range, right? Not so much. As previously mentioned, they prefer higher elevations and cooler temperatures. East of the Hogback the sun bakes barren soil, much like the south facing slopes of our mountain passes where Aspen are rarely found. Even with ample irrigation, the dry air of Eastern Colorado stresses Aspen through the long, hot days of Summer. I like to say that I love Aspen…in Aspen. Down here they struggle, and weak trees become susceptible to various bacterial diseases and leaf blights.
As you gaze upon a grove of Aspen Trees in the mountains, you are likely looking at a single Aspen tree with multiple trunks! Did you know that Aspen colonize by sending up trees from sprawling root systems? Technically a single tree even though you see dozens or even hundreds of seemingly independent trees. In fact, an Aspen grove spanning over one hundred acres in Utah, named “The Pando Tree”, is considered the largest single living organism on earth!
This information is useful on trivia night, but it also means that Aspen often send up trees in your lawn, gardens, your neighbor’s lawn, and generally anywhere you didn’t intend to plant a tree. The surface roots can tear up your grass, much like their close cousins the Cottonwood. And like Cottonwood, they have cottony seeds that can clutter up the garden and can also sprout trees. These attributes make them less than desirable trees for most residential gardens along the Front Range.
Even if you can get them to grow successfully, Aspen tend to be short lived down here, usually expiring within 15-20 years. I see Aspen in various stages of decline whenever I drive through a mature neighborhood. Still, if you need a quick screen and intend to be in the house for only a few years Aspen might be suitable for your needs. I don’t feature Aspen on my website so if you insist on Aspen call or email for availability and pricing. The best way to appreciate Aspen is by blasting turns on a powder day through a north facing Aspen glade at Steamboat, Beaver Creek, or, naturally, Aspen!
To plant or not to plant?
The Mighty Cottonwood!
By Chris Leinster - July 13, 2025
Cottonwood are on the very short list of Shade trees native to the Front Range and Colorado’s Eastern Plains. Always found growing in lowland areas along stream banks and river beds, or in dry arroyos where they receive seasonal water. They are close cousins of Aspen in the Poplar family of trees, and share many of the same characteristics, such as fast growth and adaptability. Cottonwood grow much larger though, soaring up to 100’ and just as wide! I’ve seen ancient Cottonwood with massive trunks at least 10 in diameter.
So should you plant one? Probably not. Cottonwood shed cotton. Lots of cotton, hence the name. The cotton carries seeds adrift on the wind where they can colonize anywhere they find water. Or the cotton covers your patio furniture and clogs your air conditioner. For that reason alone, many homeowners avoid them. There are, however, cotton-less varieties available, so perhaps a better choice if you need Cottonwood. There are other problems to consider as well.
Cottonwood are shallow rooted, meaning they will spread surface level roots across your lawn in search of water. These roots often break the surface, creating ankle biter obstacles sure to ruin your frisbee game. Roots can spread as wide as the tree canopy, taking over the yards of most suburban properties. Cottonwood are also twiggy, and constantly shed their branches throughout the Summer. You’ll be picking up sticks and twigs after every gusty storm.
If you have a rural property in the Foothills or Eastern Plains, or are planting in a meadow or prairie, or perhaps in a neighborhood common area, Cottonwood may be an acceptable choice. They are quite drought hardy once established. They grow incredibly quickly and provide broad shade. They provide a sanctuary for wildlife. They are salad to deer and elk though, so consider deer fencing or deterrents if planting in habitat. They are quite picturesque as well. Walk into any art gallery and you’ll likely see pictures or paintings of massive Cottonwood trees lording over abandoned farms.
While Cottonwood are probably not likely candidates for most suburban landscapes and lawns, Native trees should always be considered where space and aesthetics allow. They are an excellent choices for mountain communities and can be found growing up to 9,500’. We don’t feature Cottonwood on our website, so please call for availability and pricing.
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So should you plant one? Probably not. Cottonwood shed cotton. Lots of cotton, hence the name. The cotton carries seeds adrift on the wind where they can colonize anywhere they find water. Or the cotton covers your patio furniture and clogs your air conditioner. For that reason alone, many homeowners avoid them. There are, however, cotton-less varieties available, so perhaps a better choice if you need Cottonwood. There are other problems to consider as well.
Cottonwood are shallow rooted, meaning they will spread surface level roots across your lawn in search of water. These roots often break the surface, creating ankle biter obstacles sure to ruin your frisbee game. Roots can spread as wide as the tree canopy, taking over the yards of most suburban properties. Cottonwood are also twiggy, and constantly shed their branches throughout the Summer. You’ll be picking up sticks and twigs after every gusty storm.
If you have a rural property in the Foothills or Eastern Plains, or are planting in a meadow or prairie, or perhaps in a neighborhood common area, Cottonwood may be an acceptable choice. They are quite drought hardy once established. They grow incredibly quickly and provide broad shade. They provide a sanctuary for wildlife. They are salad to deer and elk though, so consider deer fencing or deterrents if planting in habitat. They are quite picturesque as well. Walk into any art gallery and you’ll likely see pictures or paintings of massive Cottonwood trees lording over abandoned farms.
While Cottonwood are probably not likely candidates for most suburban landscapes and lawns, Native trees should always be considered where space and aesthetics allow. They are an excellent choices for mountain communities and can be found growing up to 9,500’. We don’t feature Cottonwood on our website, so please call for availability and pricing.
Do Japanese Maple grow here?
Try these instead...
By Chris Leinster - May 26, 2025
Japanese Maple are among the most graceful, elegant small trees to adorn any landscape. Their heavily serrated leaves evoke a tropical feel, with leaf color ranging from bright green to deep burgundy. Their many varieties can take various forms, from shrubby umbrella shaped weeping forms to upright vase shaped overarching canopies. Obviously at home in a Japanese garden, they have a place in any yard whether providing a focal point for a water feature or welcoming guests in an entryway.
Unfortunately, Colorado is far removed from their island homeland, where the trees are bathed in tropical breezes and humid fog. Colorado soil is devoid of organic nutrients and beneficial microorganisms. Our dry air and intense sunlight a mile up in the air suck the moisture right out of their delicate leaves. Wild temperature swings and hard freezes are often the death knell for these tender garden elements.
You might find success in protected sites in shady areas of downtown Denver with good soil in sheltered neighborhoods. I have tried and failed three times to nurture Japanese Maple to establishment in the Denver Highlands. While they can grow here in some microclimates, they are not a viable tree for most of the Front Range. Fortunately, there are a few plants that can substitute for Japanese Maple where a conversation piece or an unusual highlight is desired.
Cutleaf Sumac is an often overlooked plant with shaggy, serrated leaves and explosive red-orange-yellow fall color. They thrive in our arid environment even in poor soil, and actually prefer it on the dry side once established. Usually available only as small container shrubs, it may take a few years to develop into a glorious multi-stemmed large shrub or small tree, but they grow very quickly and can be selectively pruned to achieve almost any desired form. Admittedly, they present as an anemic twiggy plant in the garden centers, I think because they like it dry but need to be watered every day to keep them alive in the containers. With a little patience and selective pruning and care, your friends will be amazed by the wildly extraordinary plant you cultivated for your garden masterpiece. But beware, Sumac are thicket forming and can self-sow, so some maintenance may be required to keep them in check.
Elderberry are native to Colorado and hybridized forms may rival Japanese Maple for their leaf form and color! Consider Black Lace Elder, with burgundy, almost purple finely serrated leaves. They look more like plants you would find in Florida or Hawaii, but they’re right at home in the Colorado High Country. In Portland, these plants will grow over the roof line, but expect more like five to ten feet in our less than desirable growing conditions. Again only available as container shrubs, give them a couple of years to provide that “wow” factor, but savor every moment of anticipation as they evolve. These too can be shaped and trained into small trees, and actually will respond well to a good haircut in late winter, reviving them and causing a flourish of new bright green growth above a deep purple base. Bonus points, they produce lacy white flowers in June for a pop of late spring interest!
If you’re looking for a larger tree in your landscape, but want something that maybe reminds you of your vacation in Tahiti, check out Golden Raintree. Perfectly suitable for our harsh climate, Golden Raintree is a fast grower reaching about 30’ tall. Their serrated bipinnately compound leaves will have you thinking you’re in an Asian jungle. Perhaps best in the multi-stemmed form, they’re perfect for shading your deck or patio. Panicles of bright yellow flowers shower the tree in mid-summer, hence the name! Summer flowers, and especially yellow flowers, are rare. These trees will stop traffic if planted in the front yard! But the show’s not over, flowers are followed by puffy, papery seed pods, often compared to Chinese lanterns, and not considered messy by any means. Perfect for uplighting as the light can penetrate well up into the overarching canopy, dump your Japanese Maple and plant Golden Raintree!
Just because a tree is sold here doesn’t mean it will grow here. If money isn’t an issue and you have a high risk tolerance, then by all means give Japanese Maple a shot. Heck, I recently noticed one doing quite well in the Back Country in Highlands Ranch, where they have no business succeeding. Granted it was against a north facing wall in a raised planter with good soil in a protected spot, but I’d say they got lucky. You can achieve that Japanese Maple look with the above recommendations, and compliment with Fernbush, Fine Line Buckthorn, and Scarlet Yucca to complete the effect.
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Unfortunately, Colorado is far removed from their island homeland, where the trees are bathed in tropical breezes and humid fog. Colorado soil is devoid of organic nutrients and beneficial microorganisms. Our dry air and intense sunlight a mile up in the air suck the moisture right out of their delicate leaves. Wild temperature swings and hard freezes are often the death knell for these tender garden elements.
You might find success in protected sites in shady areas of downtown Denver with good soil in sheltered neighborhoods. I have tried and failed three times to nurture Japanese Maple to establishment in the Denver Highlands. While they can grow here in some microclimates, they are not a viable tree for most of the Front Range. Fortunately, there are a few plants that can substitute for Japanese Maple where a conversation piece or an unusual highlight is desired.
Cutleaf Sumac is an often overlooked plant with shaggy, serrated leaves and explosive red-orange-yellow fall color. They thrive in our arid environment even in poor soil, and actually prefer it on the dry side once established. Usually available only as small container shrubs, it may take a few years to develop into a glorious multi-stemmed large shrub or small tree, but they grow very quickly and can be selectively pruned to achieve almost any desired form. Admittedly, they present as an anemic twiggy plant in the garden centers, I think because they like it dry but need to be watered every day to keep them alive in the containers. With a little patience and selective pruning and care, your friends will be amazed by the wildly extraordinary plant you cultivated for your garden masterpiece. But beware, Sumac are thicket forming and can self-sow, so some maintenance may be required to keep them in check.
Elderberry are native to Colorado and hybridized forms may rival Japanese Maple for their leaf form and color! Consider Black Lace Elder, with burgundy, almost purple finely serrated leaves. They look more like plants you would find in Florida or Hawaii, but they’re right at home in the Colorado High Country. In Portland, these plants will grow over the roof line, but expect more like five to ten feet in our less than desirable growing conditions. Again only available as container shrubs, give them a couple of years to provide that “wow” factor, but savor every moment of anticipation as they evolve. These too can be shaped and trained into small trees, and actually will respond well to a good haircut in late winter, reviving them and causing a flourish of new bright green growth above a deep purple base. Bonus points, they produce lacy white flowers in June for a pop of late spring interest!
If you’re looking for a larger tree in your landscape, but want something that maybe reminds you of your vacation in Tahiti, check out Golden Raintree. Perfectly suitable for our harsh climate, Golden Raintree is a fast grower reaching about 30’ tall. Their serrated bipinnately compound leaves will have you thinking you’re in an Asian jungle. Perhaps best in the multi-stemmed form, they’re perfect for shading your deck or patio. Panicles of bright yellow flowers shower the tree in mid-summer, hence the name! Summer flowers, and especially yellow flowers, are rare. These trees will stop traffic if planted in the front yard! But the show’s not over, flowers are followed by puffy, papery seed pods, often compared to Chinese lanterns, and not considered messy by any means. Perfect for uplighting as the light can penetrate well up into the overarching canopy, dump your Japanese Maple and plant Golden Raintree!
Just because a tree is sold here doesn’t mean it will grow here. If money isn’t an issue and you have a high risk tolerance, then by all means give Japanese Maple a shot. Heck, I recently noticed one doing quite well in the Back Country in Highlands Ranch, where they have no business succeeding. Granted it was against a north facing wall in a raised planter with good soil in a protected spot, but I’d say they got lucky. You can achieve that Japanese Maple look with the above recommendations, and compliment with Fernbush, Fine Line Buckthorn, and Scarlet Yucca to complete the effect.
April snows bring May, er, flower shows?
Late season snow strikes again!
By Chris Leinster - April 18, 2025
How do you make it snow on April 18th? Untie all your trees and shrubs and fire up your irrigation system on April 13th! Yep, spent last night re-wrapping my trees and draining my system. Oh well, Colorado, right?
Actually, the snow is a blessing and couldn’t have come at a better time. Nature knows grasses, trees, and shrubs are “waking up” from their winter slumber, and desperately in need of water. Temperatures shouldn’t be severe enough to do any serious damage, although heavy snow loads could be problematic.
Colorado isn’t always so kind, and some years see less early Spring precipitation. For this reason, Winter watering is essential to help your living landscape plants thrive. Roots actually start to stretch before any top growth is essential. Water begins to flow up the trunks to nourish swelling buds and crispy evergreen needles. It is very stressful on the trees if the ground is bone dry, so drag out the hoses and water if we’ve gone a week or two without any rain or snow. Just be sure to disconnect your hose from the tap to prevent any overnight freeze damage.
Warm temperatures create heavy, wet snow. As it collects on tree and shrub branches the weight can bend or break loose limbs. Gently wrap multi-stem trees and shrubs with garden tie, twine, strap, or even bungee cords in the Fall. This will help support the trees and prevent breakage. Don’t cinch the bundles tightly, just loosely wrap so the limbs have some support under heavy snows. Get out and gently shake the snow off tender plants as best you can as well.
Hopefully your trees retain some flowers and the leaves can withstand the dip in temperature. Some years bring much greater late freezes, and these can damage the leaves of early bloomers. Fret not, evolution and nature has gifted trees with “latent” buds. These are leaf buds held in reserve for just such an occasion. Hormones are triggered upon the sudden loss of leaves, and most trees should recover beautifully within a few weeks.
You can safely remove trunk wrap once the leaves emerge on your trees. The wrap does not keep the trees warm, it protects the trunks from sunburn, just like a long sleeved shirt. At this altitude, intense sunrays can penetrate the soft tissue of young trees. Continue to do this every year until the trees develop a corky protective bark.
Good luck and get out to bag some late season skiing! And now is a great time to plant!
Read More...
Actually, the snow is a blessing and couldn’t have come at a better time. Nature knows grasses, trees, and shrubs are “waking up” from their winter slumber, and desperately in need of water. Temperatures shouldn’t be severe enough to do any serious damage, although heavy snow loads could be problematic.
Colorado isn’t always so kind, and some years see less early Spring precipitation. For this reason, Winter watering is essential to help your living landscape plants thrive. Roots actually start to stretch before any top growth is essential. Water begins to flow up the trunks to nourish swelling buds and crispy evergreen needles. It is very stressful on the trees if the ground is bone dry, so drag out the hoses and water if we’ve gone a week or two without any rain or snow. Just be sure to disconnect your hose from the tap to prevent any overnight freeze damage.
Warm temperatures create heavy, wet snow. As it collects on tree and shrub branches the weight can bend or break loose limbs. Gently wrap multi-stem trees and shrubs with garden tie, twine, strap, or even bungee cords in the Fall. This will help support the trees and prevent breakage. Don’t cinch the bundles tightly, just loosely wrap so the limbs have some support under heavy snows. Get out and gently shake the snow off tender plants as best you can as well.
Hopefully your trees retain some flowers and the leaves can withstand the dip in temperature. Some years bring much greater late freezes, and these can damage the leaves of early bloomers. Fret not, evolution and nature has gifted trees with “latent” buds. These are leaf buds held in reserve for just such an occasion. Hormones are triggered upon the sudden loss of leaves, and most trees should recover beautifully within a few weeks.
You can safely remove trunk wrap once the leaves emerge on your trees. The wrap does not keep the trees warm, it protects the trunks from sunburn, just like a long sleeved shirt. At this altitude, intense sunrays can penetrate the soft tissue of young trees. Continue to do this every year until the trees develop a corky protective bark.
Good luck and get out to bag some late season skiing! And now is a great time to plant!
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