This year marks 20 years that I have worked in the horticulture industry, the majority of it for a major brand that shall remain nameless, though I think you’ll figure it out. One of my favorite privileges of working for the brand network was meeting plant breeders. They are an eclectic bunch of people. From backyard breeders to corporate breeders, the only thing I can say most of them have in common is how humble they are about the accomplishment of bringing a plant to market. The brand I knew took a minimum of 3 years of trialing and only accepted 3% of those trialed for introduction. Which is why I was always awed when someone would gesture toward a person in a room and say “That’s so-and-so, they bred the (insert plant name here).” It was always someone else pointing them out because when you met the breeder, they would never mention it themselves.

Did you know that Christensen’s has our very own Rockstar? He’s too humble to mention it himself, but Jeff Good found a sport on his Weigela and has been working with the Proven Winners shrub division to bring it to market.

Bubbly Wine™ has bold, bicolor lime and deep green foliage with a petite, pretty pink flower. With a height of one and a half to three feet, but a width of two to three feet, Bubbly Wine is often a ball of color in the garden. Like all variegated plants, you may see some reversion to solid colors, but trials have shown this to be at a lower rate than most industry standards.

Recently, my wife and I celebrated what would have been the 100th birthday of her Aunt Ruth. Every family has at least one of these relatives. You know, the ones that keep the family together and focused. It's been tough on the family cohesion since we said goodbye to her. Ruth was a product of the Great Depression - frugal, smart with her money, hard-working, yet generous. Like many of her generation, she saved and re-used to a fault - old-fashioned recycling. Most notably she never threw away a good box. Somewhere somebody or something could always use a good box. Sometimes, we would open up some of the boxes only to find inside, you guessed it, more boxes. As she neared 90 my wife said she was a very neat, organized hoarder.

Well, at Christensen's we have thousands of good ‘boxes’. But we don't hoard them, we sell the #*%@ out of them. No sooner does a new group of boxwoods arrive when you see swarming sales reps tagging off pre-sold material, often arguing over whose customer is first in line on the backorder list. It can get ugly! Stock has moved so quickly that there are usually large patches of open gravel, usually only seen in early spring or late fall.

However, Buxus is not the only game in town. Many contractors have comfort zones so they don’t necessarily look at other options. But they are missing the opportunity to diversify their selection.

The most obvious substitution for boxwood is another broadleaf, such as Ilex. Box hollies are perfect but unfortunately do not consistently perform through our desiccating winters. Ilex opaca, or Inkberry, performs well and the newer varieties, Shamrock and Gem Box, can easily be mistaken for boxwood.

Azaleas are also perfect, but many shy away from the Rhodoendron family due to a perceived difficulty in establishing these plants. Contractors who do not plant these may not realize the need for a premium (more nutrient rich) medium and plenty of fertilizer. Also, the timing of the plantings of many broadleafs can make the difference between success and failure. Getting the plants rooted early will help the growth and development of Azaleas. If you add these practices into your Azalea planting routine, they make an excellent flowering substitution.

The newest group at Christensen’s is Box Honeysuckle, Lonicera nitida 'Thunderbolt.' Yes, this honeysuckle is evergreen, and its species describes it as shining and glittering. This and more box honeysuckles seem to be making their way here by way of Europe. It is much faster growing than Buxus and can be trimmed into any imaginable shape. This lends itself to both traditional and more contemporary applications.

Our Aunt Ruth was quite the world traveler. She probably saw hedges of these Honeysuckles years before I learned of them. And, I'm sure there are many beautiful hedges at her current home.

Even before supply shortages, not a day goes by at Christensen’s Plant Center that requested nursery items (despite our fairly well-stocked and varied yard) are not available. High demand and scarcity in some areas certainly exist but smaller evergreens and woody ornamentals are in fairly good supply. When confronted with an unavailable or low quantity of a given shrub variety we work too hard to supply the exact variety when there are other ways to solve the problem. Especially in the areas of woodies, there are many interchangeable plant varieties.

During our COVID lockdowns, the one thing most people had was lots of time. There was a huge surge in interest in family histories; there were many searches on Ancestory.com and DNA samples sent to testing sites like 23andME. Discovering our past and finding distant relatives helped to fill the gaps in our social lives. The similar traits and DNA that make people a family exist as well in plants. Just as with people, plants have many traits and characteristics that define them and link them into family groups.

For sake of example, I am focusing on parts of the Honeysuckle Family (Caprifoliaceae). The Korean Spice Bush (Viburnum carlesi) is frequently requested around Mother’s Day. If we run low on this particular plant be assured, that there are a good number of solutions close at hand. Sibling variants, cousinly hybrids, and backcross hybrids are in good supply. What links them all together is the wonderful fragrance of spring after winter’s grasp. The following all offer a possible substitution for the original depending on the application. Larger in form with pinker buds is the well-known V. x juddii; also larger but with many more pink buds and semi-evergreen leaves are V. x burkwoodii and V. x burkwoodii ‘Mohawk.’ A smaller alternative with very large flowers is V. ‘Cayuga.’ These and more offer easy choices without leaving the species.

In a second example, we compare the genera Weigela and Diervilla both of the Honeysuckle Family. The Asian genus Weigela florida is everywhere in our landscapes. W. ‘Wine and Roses’ and others began the flood of pink-dominant flowering varieties. A painter’s palette of foliage colors defines this species of Weigelas. The genus Diervilla of eastern North America is a b & b plant (browsing and bumblebees). In its native circumstances, it has been browsed by moose and deer without ill effect and is an obvious favorite of bumblebees with its clusters of yellow, honeysuckle-like flowers. With the advent of the Kodiak series, Diervilla is now an active participant in landscapes still retaining its native status. These honeysuckles were separated by thousands of miles, but both possess unmatched foliage variety and the ability to flush vibrant new growth after a good trim. They have very similar leaf shapes and their phyllotaxis of alternating leaf patterns attest to their being of the same family.

Linnaeus and the Taxonomy of Horticulture give us the guidelines we need to find solutions to shortage problems. A shortage of plants just gives us an opportunity to expand our imagination and use the tools already at hand.

How's everyone doing? I think we are now past the worst of the summer heat but to be honest I was ready for fall weeks ago. We may like to complain about the weather but when you are out in the hot burning sun day after day I think it's justified. Congratulations on making it through the dog days! Labor Day is the traditional end of summer but you and I both know there will be weeks of beautiful - even hot - weather before we trade sunscreen and Gatorade for hoodies and Carhartts. But today, let's get out of the sun for a minute and do some shade gardening.

I'm a big fan of shade gardening, and the plants that thrive in shade and partial shade. I used to have an enormous Hosta collection but now that I am gardening in the country I had to scale back on those because they are basically expensive entrées for our hordes of deer. I keep a few favorites behind fences but out in the yard I have better luck with ferns. 

Lest you think that all ferns need daylong shade, I have quite a colony of Ostrich fern that do just fine in nearly full sun. In fact they were getting a little carried away so I had to take some of them out. Here they are happily crushing my baptisia.

You're going to need to provide supplemental water especially under big trees, but established ferns can be surprisingly drought tolerant. Maidenhair fern can be a little fussy but Autumn, Lady, Male and Cinnamon fern are all happy in part sun to full shade, which is also where you will find ME when it's 90° or better. And you should really try to have some Painted fern if at all possible. 

So let's take a break from summer heat and enjoy this word search puzzle created by our very own Jeff Good. (Answers here)

In 1892 a German physician, Richard Pfeiffer, believed he discovered the culprit that caused the Influenza Epidemic of 1889-90. An Infuenza bacillus became the focus of attention in the fight against the Spanish Influenza of 1918-19. Vaccines were being developed just as they had 100 years earlier for smallpox. Medicine had already conquered rabies, tetanus, anthrax and cholera before the new century. But they would prove ineffective and the Great Pandemic would simply fade away.

In 1933 an article “Failure of a Bacterial Vaccine...Against Influenza” announced the discovery of a new pathogen, a virus, Influenza A. Five years later Doctors Salk and Francis would develop the first vaccine for Influenza A and B. But the H1N1 virus has not faded away. It was believed to have caused the epidemics of 1848-9 and 1889-90. In my lifetime it has resurrected in 1957, 1968, and again in 2009. These pathogens are genetic strands looking for a way to replicate. Unlike bacterium which can reproduce outside or inside another living organism a virus can only replicate in a host living cell. For this reason viruses actually become less deadly as they mutate. Without a host their fate is in jeopardy as well.

Viruses are spread initially and primarily by mosquitoes, ticks, and sand-flies. When conditions for these arthropods are good they create an environment for the spread of these pathogens to plants, animals, and humans. Just like the mistakes of the past many plants problems have been attributed to bacterium or fungal disease, when, in fact, there are many viruses that can affect plants and threaten our food supply.

Many of these viruses in plants manifest as mosaics. Cucumber Mosaic Virus (CMV), zucchini (CYMV), and tobacco (TMV) are just a few of the predominate. TMV, in particular, hitchhikes on aphids and other insects; it affects many of the Solanaceae family, including tomatoes, peppers, and potatoes. Mosaics can show up as mottlings, variegations, mutilated leaves, and more. What is significant is these disfigurements are not caused by the virus but by the plants fighting off the virus. A plant’s own genetic material will recognize the intruder and try to cut off its path with its enzymes and other defense mechanisms, called the Argonaut complex. It is this shotgun approach that does damage, but plants can win in this process. Science, as in the study of viruses that affect humans, must realize the most effective and least destructive complex. The result is treatments such as vaccines. In plants they are sprayed or rubbed onto the foliage ( probably no needles).

In the landscape industry, we have had two recent incidents of viruses affecting planting material. In 1996 Hosta Virus X (HVX) was recognized. It is a sap to sap vehicle that spreads this pathogen. In the beginning many of the mutations to hostas were thought beautiful and desirable. But the degradation and spread by mere proximity and handling brought the problem to a head. Culling of affected plants, spacing of plants, and more recently testing for virus at plant production sources have all but eliminated the problem.

In 2011 the greenhouse growers were faced with Impatiens Necrotic Spot Virus (INSV). The result was a loss of cash crop for several years as growers sought out strains resistant to this virus. Noteworthy is the fact that many viruses in plants are actually passed on by seed.

Although genetic mapping is still relatively new it is beyond hopeful that science and medicine will be able to give us the tools to fight these pathogens and protect our food supply.

A recent article by my coworker Matt reminded me of this old saying. It’s born of the experiences of many rock and perennial gardeners. Throughout the years gardeners have collected and experimented with plants, looking for ways to use plants not necessarily accustomed to their soil type or zone. Their answer, in part, was raised rock gardens. Not only aesthetically pleasing, this approach created mini-climates in small spaces much in the same way mountain ranges create dramatic changes in flora from ridge to ridge. Lush forests give way to arid deserts on opposing side of the same mountains.

Rocks and raised beds give plants good drainage. Many perennials in the North die, not from cold, but from excessively wet ground conditions. Perennials such as Dianthus, Lavandula, Gaura, Thymus, et al. thrive in their first plantings only to rot during their juvenile winters. Perennials with long tap-like roots such as Lupines, Hollyhock, Foxglove to name a few die from crown rot due to excessive surface moisture. The fence post problem – solid above and below the ground but rots off right at ground level.

Ground-covering plants like Sedums, Ajugas, Thymus run along filling the crevices, encouraged by the cool, moist conditions. The seed of many annuals and perennials find some of these same places to spend their first winter, where they experience death and rebirth in the stratifying process. A true, natural nursery.

Rocks help ease the stress of extreme temperature change. In the summer they create cool, moist conditions on their down side. In the winter they warm with the sun, giving roots some protection against the cold. Gardeners were often able to include plants that were a zone less hardy. This also works for woody ornamentals that are usually considered sub-shrubs such as Buddleia, Caryopteris, Callicarpa, Hypericum, Crape Myrtle, and more. These types of woodies experience varying degrees of dieback but recover well from roots and heavier wood. Even just tucking hand-sized rocks around the base of perennials and shrubs can give protection and anchor the late-planted.

So when it comes to planting, if you’re ever in doubt, just go get one.

Photos © Holly Christensen, except mountain scene (Storyblocks)

Social Distancing for... plants? Yes, you read that right.

Social distancing for plants has two distinct applications.

The first is to keep plants apart that simply don’t get along well. Examples include those affected by Cedar-Apple Rust such as crabs, hawthorn, and quince and their alternate hosts of Juniper (virginana, horizontalis, and scopulorum). The deciduous get orange spots on their leaves and early leaf droppage while junipers get galls. Similar to this is Pear Rust which affects our ornamental Asian Pears , Bradford, Cleveland, et al. This, too, is caused by over-planting and proximity to Juniper species. The results are similar to Cedar-Apple Rust. A more recent fungal problem exist with our boxwoods and pachysandra. While not alternating hosts, plantings of these as complementary may increase risk of Boxwood Blight. Some genera simply need some distance or even not being included in the same landscape altogether.

The second application of plant distancing is proper spacing. This requires planning and knowledge of plant size, growth rates, and growth habit. The first crime in planting I would call the model home or interior-decorator syndrome. The landscape is planted for the here and now. It has to look lush and lived-in – NOW. The result in a few years is usually a crowded, jungle-like landscape. Much of the original plant material will need to be pulled out. The second crime is a planting that looks nice but really does not reflect the true growth habit of what has been incorporated into the landscape. Remember the Colorado Blue Spruce on the corner of the house; thirty years later you cannot see the house. The development of columnar trees and evergreens has solved this problem. Also, the introduction of many dwarf or compact versions of the old standby varieties has expanded the pool of variety and color palette. Only people my age remember the old Vanicek Weigela (a monster) that yielded to W. fl. ‘Red Prince.’ And now, we have Weigela florida: ‘Wine and Roses, Fine Wine, Dark Horse, My Monet, et al.’ How small can they get?

The art and discipline of plant spacing depends on a great knowledge of plant growth rate and maintainable size. If a new landscape is developing nicely in about three to five years, then you did a good job of placement. Larger trees and evergreens can take around three years to really establish. This is evidenced by greatly increased leaf size and improved coloring in evergreens. From this point on you should see an increase in growth rate. Most woody ornamentals are filling in and exhibit much heavier blooms during this same time. Perennials and groundcovers establish showing very little top growth first season – the Iceberg Effect (roots first, then foliage and flowering the next season).

We are at the mercy of tag information which is far from perfect and landscape architectural drawings rendered by an industry with low plant knowledge. If you take your landscape installation seriously and are interested in long-term results, become familiar with nursery varieties as fast as you can and keep up with new introductions.

We’re not talking about something not agreeing with you. We’re asking can plants pass on disease to humans?

Humans have a number of viruses in common with plants and animals. Three such families exist: the Bunyaviruses carried by insects (like mosquitoes, ticks and sandfly) causing the diseases Crimean-Congo Hemorrhagic Fever and Rift Valley Fever and rodents causing Hantavirus infections; the Rhabdovirus better known as rabies causing encephalitis; the Reoviruses which causes gastrointestinal and respiratory disease primarily in infants and young children.

Many of us have experienced dermatitis from poison ivy and other plants. People often misidentify plants and become sickened or even poisoned after ingesting. A fairly common disease throughout the world is Sporotrichosis caused by the fungus Sporothrix. This fungus exists in soils, plant debris, sphagnum moss, hay, and on rose thorns. It usually enters the body through small cuts or punctures from rose thorns ( sometime called the rose-gardener’s disease). It can manifest as small bumps or blisters at entry site, more seriously if breathed in it can cause a type of pneumonia, and if entry wound is near a lymph node it can become disseminated throughout the entire body.

Another common and opportunistic pathogen is Pseudomonas aeruginosa. It’s what causes soft rot in plants, fruits, and vegetables. It is especially dangerous for people with immunity deficiencies causing pneumonia, urinary tract infections, and oral infections. And, similar to the staph that causes MRSA it is antibiotic resistant. Much of what has been mentioned results in disease caused by the myotoxins produced by the bacterium.

More recently in France people have been showing symptoms of fever, aches, and pruritus (a systemic itching usually caused by a disease) after eating peppers with mild mottle virus (PMMoV). Viable virus has been found in salsas, powdered spices, and in the samples of hundreds of people. Viable tobacco mosaic virus has been found in the mucus and thoracic fluids of smokers.

In India tospoviruses causing tomato spotted wilt and groundnut bud necrosis are passed on by insects, thrips, and humans. Live virus is found in ripe tomatoes only to be eaten and passed on through ground and water. Begovirus which causes the tomato yellow leaf curl virus affects tomato production worldwide and, in turn, affects the insects that carry it by shortening their lifespan and their ability to reproduce.

So as you can see, plant diseases have many paths to make humans sick - but none of the pathogens has, of yet, crossed the line of entering the human cell. Plant diseases for now have no direct route as a human pathogen.

I still remember planting my first serviceberry with my dad a long time ago – actually, a very long time ago. What struck me most were the many names for the same plant – Amelanchier canandensis, Shadblow, Juneberry, Serviceberry. Somewhat unusual at that time, little did I realize what a high-demand plant it would become. Therein lies the problem. It seems no matter how many are brought in every year we quickly run out. Landscape contractors, designers, and architects ignore so many other great similar-usage plants. Even when repeatedly told we are out till fall dig season, the requests keep coming. There are many good substitutes. In fact, there are many plants that would be better first choices!

Even more shade tolerant than Amelanchier are witchhazels. Larger, fall-blooming, native Hamamelis virginiana could match serviceberry with respect to growth rate and size. H. vernalis and the many crosses of H. mollis and chinensis (i.e.’ Diana, Jelena, Arnold Promise,’ et al.) are slower-growing but offer patio shade and a much greater color range. Native multi-stemmed dogwoods (Cornus florida and fl. ‘Rubra’) give a layered look; same usage but different than the arched or cascading habit of A. canadensis.

Also, a terribly-ignored, rugged, and problem-free group of plants are the Wrinkled Viburnums. In particular, Viburnum rhytidophyllum, Leatherleaf, and V. x rhytidophylloides ‘Willowwood’ are monsters. Achieving height and spread toward fifteen feet, they have an arching habit and are semi-evergreen. These offer spring flower, fruit, fall color, (and winter foliage interest).

A perfect match for Amelanchier ‘Rainbow Pillar’ is Cornus mas ‘Golden Glory.’ This Male Dogwood is very hardy and an early bloomer not usually susceptible to freeze damage. It has exfoliating bark and edible fruit. Its structure provides great winter interest.

Another easy sub for Amelanchier is Viburnum prunifolium, native Blackhaw, large, global, and a great bird attractor. A shrub easily surpassing fifteen feet in height and spread.

So, yes, there is life after serviceberries. I can't promise you that these or any other plants are going to be in stock when you are looking for substitutions, so don't be afraid to consider other options. Let's enhance our landscapes in terms of variety and plant health!

We do this all the time!

We over use, we abuse, we’re in a hurry, and we’re lazy! The landscape/nursery industry is a repeat offender! We have our “go-to,” easy-money plants. On the surface that doesn’t seem to be a bad thing. Almost every contractor has their favorite group of plants; almost every contractor is stuck in some sort of rut! Week after week we get the same list from contractors. Only the numbers change!

Need proof? Recent history provides great examples! Let’s start with the Green Ash. (I hope you don’t need an explanation!) Another great example is the Norway Maple. Our storage field used to have hundreds of Norways of many varieties. It’s “go-to-ness” turned it into an invasive species banned from most cities due to its ability to reseed into alleys and easement areas. The resulting offspring were often not very landscape worthy. Tree growers were left with fields of trees with no market in which to sell them!

Looming on the horizon is the fate of the beloved Callery Pear. The Bradford Pear’s (a.k.a. “Banana-Split Pear”) popularity succumbed to the hyper-popular Cleveland Pear. It’s been the near-perfect tree: Popular, household recognition! Transplanting into most any soil, great form, great bloom quality, and rich, long-lasting fall color!

The overuse of this species has led to outbreaks of Pear Rust, and its ability to reseed has begun to clog open spaces with again undesirable offspring. States and cities have begun restricting its usage. And then there’s probable, correcting fireblight….

What’s next? Will growers develop a truly seedless Callery? Or, what will be the new big seller? Haven’t we learned anything? We don’t need another “go-to” plant. This industry needs good practices and diversity!

We already offer a number of trees that would substitute well for the Cleveland Pear. Some of these are:

•  Acer rubrum ‘Brandywine’
•  Acer saccharum ‘Legacy’

• Acer x freemanii Armstrong’
• Amelanchier laevis ‘Cumulus’
• Carpinus caroliniana

• Cornus mas ‘Golden Glory’
• Ostrya virginiana
• Syringa reticulata ‘Ivory Silk’

• Taxodium distichum ‘Shawnee Brave’

Resist the temptation, don’t be a repeat offender! Mix it up out there!