Tuesday, February 9, 2021

Aralia cordata 'Sun King'

 Aralia cordata 'Sun King' has rocketed to stardom in the last several years and was named 2020 Perennial of the Year by the Perennial Plant Association. This wonderful plant was introduced by Barry Yinger of Asiatica Nursery, who brought it back from Japan. Barry brought a lot of great introductions into the country for the first time, often giving them appropriate names if their Japanese name wasn't valid. 'Sun King' was introduced to the wholesale trade by Terra Nova in 2011.

As a species, Aralia cordata is found in Japan, Korea, and eastern China. It grows to 6' or more (it's been reported over 8' in cultivation here in the states) and young shoots are cooked as a vegetable. It's the Asian counterpart to our native Aralia racemosa and is pretty similar. Both species inhabit similar niches in their range: woodland openings, woodland edges, and shaded areas of savannah. It's reportedly also closely related to another US native, Aralia hispida.

'Sun King' needs fairly good light to maintain a bright gold color. If it's in more shade it will turn chartreuse fairly quickly. So place it in bright shade, preferably with dappled light or even some direct morning sun.

'Sun King' will develop large compound panicles of white flowers, just like the plain green form of the species. Aralia flowers are generally very attractive to pollinators. Following the flowers, clusters of small black berries will form. None of my plants have done this yet, but I've always had to move away or move them before they've gotten fully mature! The berries pictured here are from a plain green A. cordata at Rotary Botanic Garden in Janesville, WI. 

It isn't a terribly picky or difficult to grow plant. I've had success with it in pots, in the garden in my silt loam here in z4, in clay-loam back in Sheboygan county, and in heavier clay soils in nursery display gardens. As long as it isn't too terribly wet or dry, it's easy to grow and worthy of its perennial of the year title. It does seem to best in fertile, well-drained soils, with some supplemental irrigation in summer. 

One of the most important things I need to stress about this plant is its mature size. Pretty much all of the commercial plant tags I've seen are incorrect, and online descriptions are often also misleading. Over and over I see this listed as growing only 3' tall x 3' wide. This plant will easily grow to 5' tall x 6' wide in 5-7 years, and larger over time. Barry's plant was certainly bigger than 3'x3' before the larger trade started growing it, judging by pics I've seen. So I'm not sure why this became the size everyone decided this would grow. A short 3 or 4 year trial maybe? I honestly don't know; but it's important to give this plant enough SPACE. Check out this specimen at Soule's Garden in Indianapolis eating its Hosta neighbors!

This is an excellent specimen or background plant for partial shade and it's easy to combine it with so many things. The compound foliage makes a good contrast with broad leaved plants like Hosta, Heuchera, Colocasia, Astilboides tabularis, Darmera peltata, Ligularia dentata, and a slew of others! The foliage is also bold enough to make a good foil for finer leaved plants like Iris, grasses and sedges, ferns, conifers, etc. 

I also think it's an excellent plant for a background to annuals and Rotary Botanic Garden made excellent use of it last time I visited. Don't be afraid to use it in beds with Coleus, or even in pots for a season and plant it in the garden at the end of the year. 

If you're not currently growing this in your shade garden, and you have the space, you really should add it. It's such a flexible plant and it's easy to grow. We'll be offering it again in the near future, probably available in late summer. 

Wednesday, February 3, 2021

Astilbe: A Horticultural Tragedy

Walk into any garden center and ask for perennial recommendations for shade. Likely the first thing to be recommended will be Hosta; the second thing will probably be Astilbe. If you're not familiar with Astilbe, they are perennials that provide essential early to mid-summer color for shaded gardens. And that summary is where our tragedy begins.

Shade tolerance is the start of our tragic tale. It's certainly true that Astilbe are shade tolerant. They're native mostly to Asia, with one species currently present here in North America, and are naturally found in forest edges, ravines, and other somewhat shady locales. Shade tolerance does not mean shade loving. They need bright light, preferably some direct sun, to perform their best. Given adequate moisture, they can even tolerate full sun in cooler climates. Placed in heavy shade they might grow fine, but are likely to bloom poorly, if at all, on less sturdy stems. Plants will likely be thin rather than dense. 

Adaptability is the next chapter of our tragedy. Most species of Astilbe are found in fairly moist habitats with rich organic soils. While they are somewhat adaptable to less wet environments and a range of soil types, they are not at all adaptable to dry gardens or clay soils. 

The best Astilbe I've seen were planted in an area that was receiving 2" of water per week from automated irrigation. They were lush and had hundreds of blooms on tall 40" tall stems; the best marketing images pale in comparison to these plants. The average homeowner, gardener, or landscaped business does not (and given future water availability concerns, probably should not) provide this amount of water. 

Most of us don't have ideal soil either; here in WI we mostly have heavy clay or sandy soils. Neither is ideal for Astilbe, which like organic rich soils. Fortunately, most shade tolerant plants also like organic rich soils, and if you plan ahead you can easily create raised areas to accommodate them. 

A special chapter of this tragedy goes to Astilbe chinensis, or if we use the currently correct name, Astilbe rubra. This chapter is titled: Drought Tolerance is a Lie. Astilbe rubra is found in equally moist habitats to other species. It tends to be more adaptable to average soils than other species, but this is NOT drought tolerance. Astilbe rubra and its cultivars and hybrids are probably the best choice for our gardens. They can go longer periods without irrigation than A. japonica or A. x arendsii cultivars and hybrids, but they will not survive actual drought conditions. In true drought conditions, plants can go weeks or even months without appreciable water. Many plants will survive drought conditions just fine. Astilbe, including A. rubra, will not. At the least they will go dormant and their health and vigor will likely be severely impacted  when moisture returns. 

Selection is the final chapter of our tragic tale. There are A LOT of Astilbe cultivars available. George Arends was instrumental in popularizing the genus, and introduced at least 74 cultivars over the span of 50 years. That quantity and pace has continued to this day. Just a quick browse of 4 wholesale suppliers turns up 70 cultivars. 17 of them are older cultivars but the bulk of the rest have been introduced in the last 25 years. 6 are new for introductions for 2021. A quick search of plant patents turns up 60 different patented cultivars. There is certainly room for a large pool of unique cultivars. But many of them are just incremental improvements over cultivars introduced prior to 1960. Slight differences in color, height, bloom count, etc. really bogs down consumers who are just looking for a great plant.  

The conclusion of this tragedy is that gardeners and homeowners are being set up to fail with a really fantastic plant. The horticulture industry needs to stop heavily recommending it to non-gardeners and beginning gardeners who are destined to fail because we don't educate them properly. The myth of drought tolerance needs to be dropped from our collective vocabulary in regards to this genus. At this point we need quality over quantity and inferior plants should be dropped from wholesale and retail offerings. To some extent this is happening; but probably not as much as needed. There also needs to be more extensive comparative trials in place, though the trend is for there to be fewer trials these days.

I love Astilbe, I intend to continue to expand the selection of cultivars we offer and trial varieties here in the garden to see which perform well for us and which can just fade into horticultural history. I'm even interested in breeding some more novel forms, but I don't know if I'll get around to that project. If you're struggling to grow Astilbe; water them more, maybe improve their soil if it's well-drained or heavy clay, move them into morning sun and afternoon shade or dappled light if they're growing in heavy shade. They will reward you with essential color in early to mid-summer. 

*a couple quick footnotes:

Astilbe crenatiloba is also a North American species, but it hasn't been found since the 1880s and is likely extinct or possibly just a variant of A. biternata

This post is absent of pictures because I've seen so few great looking Astilbe in the landscape that I've not managed to photograph them. When I *DO* see good ones it's not during bloom season! 

Tuesday, January 19, 2021

Hybrid Echinacea

14 years ago Echinacea ‘Art’s Pride’ ORANGE MEADOWBRITE arrived on the market and the world of coneflowers was changed forever. This hybrid of E. purpurea ‘Alba’ and E. paradoxa opened the floodgates of hybridizing this genus of stalwart garden plants. Soon hybrids from Richard Saul and Terra Nova nursery started hitting the market.
‘Sunrise’ from Richard Saul

‘Tomato Soup’ from Terra Nova

But these colorful new hybrids weren’t without their problems. Many gardeners had trouble keeping them alive, especially in areas with heavy soil and wet winters. This has a lot to do with E. paradoxa being found primarily on very well-drained soils rather than a lack of hardiness.

Large clumps of ‘Sunbird’ (left) and ‘Flame Thrower’ (center) with E. purpurea ‘Showoff’ (on the far right) 

Subsequent years of further hybridizing have made the newer hybrids a little easier to grow, but they still do best in well-drained soils. Provide proper drainage and they will get just as large as, or even larger than, old fashioned E. purpurea.

The best performers for me have been ‘Firebird’, ‘Sunbird’, and ‘Flame Thrower’ from Terra Nova nurseries. These are 4th generation hybrids bred from E. paradoxa and E. purpurea ‘Ruby Giant’.They’ve done very well in several gardens for me, with the ‘Flame Thrower’ pictured above at 7 years old.


‘Flame Thrower’


‘Flame Thrower’

I’ve also had fairly good luck with the Sombrero series from Ball. This is a compact series with plants reaching 18-24″ in height and several varieties in shades of orange, red, and yellow are available.
Sombrero mix

Sombrero ‘Salsa Red’

Sombrero ‘Tres Amigos’

If you’ve tried some of these fantastic plants before but struggled with them, don’t be afraid to give them another try. Improve your drainage by creating a raised bed or planting on a slope. Use aged pine bark or pumice as a soil amendment to increase porosity and improve drainage. Visit public gardens and see which varieties are doing well in your area. Don’t be afraid to fail and try again or try new varieties. Experimentation is part of the fun of gardening.

Wednesday, December 9, 2020

Heuchera Species and Hybridizing History

Heuchera wasn't always the garden rock star we know today. For almost 100 years, selections were simple green foliage with variable amounts of silver veil, possibly with small but nicely colored flowers. The flowers tended to be on quite tall stems (a trait that I like, but isn't always what you want in a design!) and short-lived.

Heucheras these days come in a various shades of green, silver, burgundy, purple, red, orange, yellow, and nearly any combination of these colors. Flowers can be a range of colors including green, white, pink, and red. Flower stems now tend to be shorter, more in proportion to the foliage, and can be long lasting or even rebloom all season. Heuchera breeders have mostly concentrated on using just 5 species. Knowing which species are used in a variety's background will help you know it's tolerances.

H. americana 'Marvelous Marble'
H. americana is a hardy woodland species.  It likes a humus rich soil and some afternoon shade and is heat and cold tolerant. Foliage ranges solid green to green with silver veil and burgundy veins. I find that hybrids with a lot of influence from this species (and others in the same subsection) do best here in the upper midwest. Zones 3-9

It should be noted that we understand Heuchera very differently now compared to the 17th century when they were introduced to horticulture. Six species were lumped under the name H. americana at the time and are likely in the background of many early cultivars. These species consist of H. americana, H. caroliniana, H. pubescens, H. alba, H. longiflora, and 
H. longiflora
H. richardsonii
H. richardsonii

H. micrantha
H. villosa is another woodland species, it also likes a rich soil.  It is very heat and humidity tolerant and seems to tolerate clay soils fairly well. Foliage tends to be somewhat fuzzy (villose) and is green. There is also a naturally occurring burgundy form, H. villosa f. purpurea Zones 4-9.

H. micrantha is a western species and prefers good drainage.  However it is also tolerant to moist soils during the growing season. Green foliage with somewhat ruffled margins. Zones 5-9, possibly colder.

H. cylindrica is a western species tolerant to harsh winds and temperature extremes, it tends to be a crevice dweller. Flowers are tightly packed on the stems.  Zones 3-8.

H. cylindrica var. glabella
H. cylindrica var. glabella

H. sanguinea is a south-western species that is extremely heat and drought tolerant. Foliage ranges from green to green with silver veil. This is where great flower colors comes from as well.  Despite its southwestern heritage it is very hardy, but requires excellent drainage to grow successfully in wet climates. Zones 3-9.

H. 'Coral Cloud' from Alan Bloom
Hybridizing Heuchera first began in the very late 1800s. Victor and Emile Lemoine introduced the first hybrid, 'Brizoides' (H. sanguinea x H. americana var. hispida f. purpurea), in 1897 and then 'Gracillima' ('Brizoides' x H. micrantha) in 1900. Many more were introduced by Lemoine et Fils over the next 20 years. George Arends (known for Astilbe hybrids, the Arendsii group) introduced 'Rosamonde' ('Gracillima' x H. micrantha 'Rosea') in 1903. These 3 represent the oldest and most popular varieties of the time and can still be found in collections to this day. 

Alan Bloom started trialing and breeding Heuchera in the 1930s and continued this passion into the 1990s. He introduced many selections originating from 'Brizoides', 'Gracillima', and others that can still be found on the market today. 

H. 'Canyon Duet'

While most breeders concentrated on the five species I talk about above, Dara Emery of Santa Barbara Botanic Garden went a completely different direction. He used various California native species, such as H. elegans, H. meriamii, and H. hirsuitissima, crossed to H. sanguinea to create a group of lovely compact cultivars that are suitable for rock gardens. 'Canyon Duet' is the most readily available of them and has proven surprisingly hardy. 

Edgar Wherry collected seed that went on to become the selection 'Palace Purple'. This plant is largely sold as H. micrantha 'Palace Purple', but that is incorrect. Wherry never collected within the range of H.micrantha and no purple form of that species has ever been discovered. It's actually a superior form of H. villosa f. purpurea. Sadly, it has mostly been seed propagated and you can get inferior forms pretty easily. 

One of the most important hybrids to ever come about is 'Montrose Ruby' from Nancy Goodwin in 1990. It's a hybrid of H. americana 'Dale's Strain' and H. villosa f. purpurea 'Palace Purple'. 'Montrose Ruby' is the foundation plant for several modern hybridizing programs and most of today's cultivars can trace their lineage back to this plant! It's the basis of Charles Oliver's great selections, originally crossed to his 'White Marble' (which is H. pubescens x H. sanguinea 'White Cloud'). Oliver also worked with H. hallii and H. pulchella to produce garden worthy compact plants like 'Petite Pearl Fairy'. 

H. 'Georgia Peach' from Terra Nova
'Montrose Ruby' is also in the background of Terra Nova's program, crossed to H. sanguinea as well as backcrossed to H. americana. Later, they would use H. cylindrica, H. micrantha, and H. villosa; as well as recently using H. richardsonii. Terra Nova has been responsible for the bulk of modern Heuchera hybridizing and lots of innovation in the genus. I would say their most important variety is 'Amber Waves'. It was the first amber-colored Heuchera to be made available and its genes are responsible for broadening the color range to include orange, yellow, and true red. They've done really great work with plants for very colorful foliage as well as great flowers. One of the best varieties ever introduced for flowers is 'Paris', from their "city series". Maybe my favorite plant of theirs is 'Georgia Peach' which goes through seasonal color changes and has proven reliable across a wide range of the US. Some of their varieties can struggle in the upper midwest. This is most likely a result of the selection pressures in Oregon being very different from the climate here and may also involve some of the different genetics they've used. Making sure you have good drainage goes a long way to ensuring success; I find that most do well here provided drainage. 

H. 'Caramel'

Thierry Delabroye has done a lot of work with hybrids involving bringing H. villosa to the forefront of hybridization. 'Caramel' is his most popular cultivar and is a nice rich amber that is fairly reliable here in the upper midwest. He's also breeding a really nice line of larger cultivars, 'Mega-Caramel' being a larger version of 'Caramel'. 
H. 'Pink Panther' from Walter's Gardens Inc.

Walter's Gardens in Michigan has recently been breeding some real knockout cultivars that are performing well in the upper midwest. They've introduced several really nice purple varieties with improved vigor and size as well as some great plants with long-lasting flowers. Many of their varieties are part of the Proven Winners brand as well, as Walter's is the breeder and marketer of their perennial line. 

H. 'Carnival Watermelon' from Ball Hort.

Another series of plants I should mention is the Carnival series from Ball Horticulture. These are widely available mass market plants that can be found affordably at box stores. They seem to be performing fairly well in the midwest, which isn't surprising since they're bred and selected in Illinois. The standouts are 'Carnival Watermelon' and 'Carnival Peach Parfait'. Other than that, I'm not too excited by the series. Most of the varieties resemble plants that were released from hybridization efforts in the 90s and I don't find them to be improvements in any way. This isn't to say they are bad plants; I'd happily sub 'Carnival Peach Parfait' or 'Carnival Watermelon' for 'Georgia Peach' or 'Carnival Plum Crazy' for 'Plum Pudding' in design work if there was a significant price or availability difference. This applies to most of the series as well. If you're a landscaper or home gardener looking to do a mass planting without breaking the bank, this series is a good option. If you're a plant collector looking for novel plants, probably best to skip most of these as there are more unique plants out there. 

I'll go into more detail about specific varieties and how they've performed for me in an upcoming post, so stay tuned!

Friday, December 4, 2020

Growing Heuchera

It's been ten years since I originally wrote about Heuchera, and an update has been a long time coming. I'm scrapping my old posts and updating them with some slight revision for clarity. This post is going to be on just general culture and species, I'll post more about hybrids and history at a later time. 

Heuchera 'Caramel' with Hostas 'Stained Glass' and 'Fire Island' and Lamium 'Purple Dragon'

Nearly everyone (including me) mispronounces Heuchera; proper pronunciation is HOY-ker-uh. I've been pronouncing it WHO-ker-uh for 25 years, and it's hard to change! The genus is exclusively American in origin, with around 37 species in the United States and Canada and another 5 found exclusively in Mexico. 

Heuchera species fall into two basic categories. The mountain dwelling species are suitable for the rock garden and well drained soils. They tend to be heat tolerant and are more sun tolerant, but still appreciate some afternoon shade as they tend to grow in the shadows of boulders or scrub. The woodland dwellers are more suitable for shade gardens. They want soils that are consistently moist but well drained with adequate organic matter. They tend to be found on woodland edges, savannahs, or grasslands. Montane species are more heavily represented in the west and woodland species more so in the east; but both groups exist across their range. Regardless of crevice or woodland, all species tend to be found in well-drained locations. 

In general, loose well-drained soil is important. Few varieties will last long in heavy or compacted soils.  Most varieties appreciate morning sun, with shade in the afternoon. Provided those 2 conditions, most varieties will do well. A little research will help determine which varieties will truly thrive in your location. Knowing where and when they were hybridized is also useful. I find cultivars bred on the west coast are less likely to thrive compared to cultivars bred in the Midwest or Northeast. 

Sunday, January 5, 2020

Round Pegs and Square Holes: Proper Planting

I've been seeing some advice making the rounds lately from many sources via social media. Plant your trees in square holes to make them grow healthier and faster. This info is being re-blogged and re-shared over and over and I'm seeing a lot of discussion about it. There may not be anything specifically WRONG with doing so, but I highly doubt it's beneficial. I planted some things in square-ish holes this fall; not because I think it's beneficial, but because it was faster to just strip a couple sections of sod off and not worry about rounding the hole. I had a lot of plants to get in the ground and time was of the essence.

What I didn't take shortcuts on was proper preparation of plants for planting. This meant root-washing or root-shaving. Because of the circumstances of the last several years, many of my plants have been potted for an extended period. Some as long as 10 years. So many have dense root systems and girdling roots. For healthy, long-term growth it's important that the root system can grow properly. Roots need to be straightened, and even pruned if necessary. Many of the plants you purchase at nurseries have been in containers for extended periods of time. They may have several layers of girdling roots and they may be planted too deeply. Rootwashing is the best way to fix these problems.

This Hydrangea arborescens was in this pot for 3 years. I use a hose end sprayer set to jet to wash off as much of the loose soil as I could.

After washing, I removed large girdling roots that were on the interior of the root mass, hidden by the soil.

This Abies concolor 'Compacta' wasn't rootwashed before being planted in the last garden, and then spent 3 years in a pot. I completely root washed it (sadly I didn't get a final picture that turned out well) and straightened most of the roots. I did have to prune a few of the worst girdling roots out.

 Even herbaceous plants will benefit from root washing and correction. Look at the girdling roots on this young perennial! They were easily straightened during planting.

This Hosta 'Bridal Falls' has a wonderful root system. A quick root wash and the roots were easily straightened out. This is how most perennials should look before you backfill the planting hole.

I mentioned root shaving as well. This is where you shave off an inch or so all the way around the root ball to eliminate outer circling roots. This is a good method for plants with dense fibrous root masses but no larger girdling roots. I did this for some azalea cultivars and a few other things that just don't easily form large support roots. Doing so ensures that the roots will grow outwards into the surrounding soil instead of staying in the shape of a pot. 

Speaking of soil, what about soil prep? Elsewhere on this blog, I talk about amending soil. Mostly I no longer recommend it. The best thing for plants is to skip amending soil with peat, compost, or other organic additives. Native soil is your best option. There are some exceptions to this, like when you create raised beds. If you're planting something that needs better drainage (I like Primula for instance) consider creating a raised bed with an appropriate soil mix for them. Some organic amendments work well for mulches, and mulch is something I strongly recommend.

How about fertilizer? Most in-ground plants need a lot less fertilizer than we give them. A soil test is essential to making decisions about fertilizer. And I don't mean a store-bought test you do at home. Contact your local university extension office for a proper soil test. 

Tuesday, September 10, 2019

New Beginnings

Remember back in 2016 when I was so optimistic about our move to the north? I thought we'd have a new property and have the business moved by spring 2017. Life has a way of not working out how you'd like. It's been 3 1/2 years, but we finally closed on a house 2 weeks ago in Antigo, WI! I now have 12 acres of trees and prairie and an old farmhouse. 

We have most of the plants moved up here from the nursery now. We still need to move the poly house, benches, equipment, etc. I don't know if I'll get the house put back up this fall, but we do have a shed that's suitable for plant storage. This shed will become our retail building in the near future. We may have some limited open days as soon as next year!

It's been a struggle having room for my personal collection AND stock for sale at the nursery. A focus this fall is getting plants in the ground so I don't have to deal with shifting things around to make room for new product. Today I put in the first garden bed. It's a small bed bordering one side of our back deck and patio. 

I started by cutting an edge and then manually removing the sod. Our soil here is nice loam and removing sod is fairly easy. I'm not opposed to using some glyphosate in larger areas with difficult to control plants (I have many such areas!) but manual removal is still the fastest way. 

There were some existing Hosta 'Francee' that I've removed. They were likely from a box store and there's a good chance they're infected with Hosta Virus X, even though they don't show symptoms at this time. They will be disposed of and this bed consists mainly of non hostas. I also removed those keystone blocks and properly graded the area so they aren't needed.

With everything removed and graded, it was time for plant selection. This area gets late afternoon sun, so it's suitable for an assortment of neat shade plants. It's also one of the more protected sites here so it was perfect for Enkianthus campanulatus and Clethra alnifolia 'Crystalina'. I'm really not sure how well the Enkianthus will do here, but I'm hoping it will survive. The Clethra should do ok. I also chose only two Hosta for this area, 'Frisian Pride' and 'Foxfire Irish Moon'. They'll provide some nice texture and color contrast to the plants around them. There are 10 seedlings from my Heuchera breeding program. 9 are crosses of 'Berry Timeless' x 'Stainless Steel' and one is a yellow 'Southern Comfort' x 'Stainless Steel' (this one may get moved into a bed with all of its siblings). I also included 'Berry Timeless' and 'Stainless Steel' in this bed for comparison. Other plants in this bed include: Astilbe 'Amber Moon', Astilbe 'Chocolate Shogun', Cimicifuga simplex 'Black Negligee', Iris tectorum ex. 'Slippery Slope', Carex platyphylla, Salvia koyamae, Geranium 'Phillipe Vapelle', Carex muskingumensis 'Oehme', Atractylodes ovata, Epimedium 'Spine Tingler', Eurybia divaricata 'Eastern Star', Athyrium niponicum 'Applecourt' and a spot is being saved for Athyrium niponicum 'Crested Surf'.

An important note about planting here. I'm fortunate that we have good soil. I don't intend to do any kind of amendment here. I'm also making sure to root wash all of my trees and shrubs and at least remove most of the soil from my perennials. My plants have been in containers far too long and It's important to fix any root issues that may be present. For trees and shrubs, this means removing all soil, pruning out any girdling roots, and making sure all the roots are laid out straight away from the plant. For perennials, I'm able to shake out most of the soil and do the same thing without aggressively washing them. I'm also able to see any pest or disease issues that may be present this way. I highly encourage you all to do this! 

I have many, MANY, more plants to get in the ground. I'll be updating more frequently now that I have a place to garden! I also have a whole lot of other projects in store, including a gradual prairie restoration and re-building a retaining wall. Expect more regular (but still intermittent!) blog posts.