Breeding a Better Spiraea



When evaluating a plant species, its cultivars and its future potential, I like to start by growing all the available cultivars in our test garden. This gives me a better understanding of the strengths and weakness of a species and each cultivar. It helps me to know how a new plant stacks up and if it has potential for release. It also helps us identify breeding opportunities.

After growing and evaluating every possible cultivar of Spiraea japonica, we came to the conclusion that there was an opportunity for plants with new and better flower color, better foliage color, improved mildew resistance and better branching. Feedback from our growers indicated they wanted more impulse appeal, mildew resistance, burn resistant foliage, more flowers. Lastly they wanted plants that required less care in production and in the landscape. With this information in hand we started breeding Spiraea.

After six years of breeding Spiraea and three more years of evaluation, we were able to narrow 1,500 potential field seedlings down to twelve candidates. We then propagated and grew on these twelve selections and evaluated them in production as one gallon and three gallons. Plants were also placed in our test garden and again compared to what was on the market. Additionally test plants were sent to key growers across the US to get their feedback. The most difficult part of the process is narrowing the selection down to one or two potential introductions. A cool wet spring made our task a lot easier. It was the perfect spring for powdery mildew. If a plant was going to get mildew, this was the spring. Mildew eliminated about half of the selections left in program.

By August two plants rose to the top as clear winners and were chosen for introduction under a series name call Double Play™. The name Double Play™ was chosen because each plant delivered two or more improved traits; primarily improved foliage and improved flower color. The first introduction is called Double Play™ Artist. This plant was a clear winner early in our field trials because it was compact, had attractive foliage coloration and unusual purple flowers. The foliage is unique because the new growth is a vibrant purplish-red color. As the season progresses the leaves mature to an attractive bluish-green color. The flowers also caught our attention. The flower color is a unique shade of rich purple that we’ve never seen before.

Double Play™ Gold is a dwarf gold leaf selection. It stood out from the other seedlings because it had no mildew, tight branching and a tidy dwarf habit, eye catching pure pink flowers and the plant did not burn when grown in full sun. This plant also stood out in our container trials, as each plant produced was a perfect little soldier with very little pruning.

Growers will begin producing the Double Play™ series next spring and I expect that will be at retail in Spring of 2010.

The Best In the West: Planting Hunting In Oregon

I've seen a lot of plants in the last five days; I've been in Portland, Oregon visiting nurseries and gardens. This is a great area to visit nurseries and see interesting plants, especially if you get into some of the smaller, more specialized nurseries. Here is just a few plants that caught my attention. What do you think?



Agastache 'Cotton Candy'
This plant is a sea of flowers. It's an easy growing, vigorous perennial that blooms from mid-summer until frost. The dense flower spikes have numerous light pink flowers. It has a compact, low branching growth habit. It tolerates dry conditions and prefers well drained soils. All Agastache are popular with hummingbirds.


Agastache 'Summer Love'
This new Hummingbird Mint has masses large red-purple flowers all summer and into fall. It forms an attractive upright mound to 36" tall and has bright green, fragrant foliage. This is a great perennial if you're in zone 6 or warmer and have good soil drainage.
Jasminum officinale 'Flona's Sunrise'
This colorful vine is a yellow version of the Poet's Jasmine vine. It is a strong climer that can reach twenty feet if you give is something to twine up. I especially like its fragrant white flowers in summer. It is hardy to zone 7 and warmer but those of you in Zone 6 might have some luck if you plant it in a protected location and mulch it each year to protect the roots.


Stokesia laevis 'Purple Pixie'
My friend and trusted Perennial Diva Stephanie Cohen turned me on to this little beauty. It is the first ever dwarf Stoke's Aster! It has large violet blue flowers and a short, compact habit that does not fall apart with maturity. It blooms in early July and sporadically until fall. It's a great little plant for the areas with high heat and humidity. Hardy to zone 5, it is happiest in full sun. It's best to avoid soils that are wet or high in lime.

More New Plants: The Plant Hunter In Europe Part II

It was quite evident that there is a lot of shrub breeding going on in Europe. It appears that the trend in shrub use continues to grow in Europe just as it is here. And based on what we saw Hydrangea breeding is as strong as ever . Here is a small sample of what we ran across on our last trip across the big pond.



Hydrangea macrophylla 'Selina'
developed by Kwekerij Sidaco. These flowers were quite striking as the flower color is an unusual color. I'm not sure how to descripe the color.


Hydrangea macrophylla 'Selma' developed by
Kwekerij Sidaco. I love the ruffled sepals and the cream and pink coloration.



Quick Fire Hydrangea paniculata - The origianl plant developed by plantsman Mark Bulk



Pinky Winky Hydrangea paniculata - The original plant develpoed by Johan Van Juylendroeek at the Belgian Breeding Station in Flanders. Note how new white flowers continue to emerge from the tip of the inflorescens.

Edgy Hearts Hydrangea macrophylla - A new series of dramatic, "edgy" plants developed by master breeder Katrin Meinl.


Edgy Orbits Hydrangea macrophylla a new lacecap with doubled sepals in the Japanese style developed by yours truly.

On the Hunt: New Plants In Europe

Having been in Belgium and the Netherlands the last week I have a back log of 7200 emails to get through. Still I promised to share some new plants with you upon my return. I don't have the time to give you greater detail than the photographs and the names but I think you enjoy the post anyway. I'll share a few more new plants as I have time.

Dicentra 'Burning Hearts'

Chamaecyparis nootkatensis 'Gloria Polonica'


Daphne odora 'Rogbret'


Populus deltoides 'Purple Wave'



Prunus laurocerasus 'Ivory'
What do you Like?

One Sweet Clethra



Clethra has long been one of my favorite plants. I’m a sucker for fragrance and few plants pack more olfactory punch than Summer Sweet (Clethra alnifolia). If you’re a subscriber to my blog then you know that I’ve been breeding shrubs for about eight years now. The first plant introduced out of our breeding program was Summer Wine Ninebark (Physocarpus opulifolius). Since then I’ve introduced two new reblooming Hydrangea called Let’s Dance Moonlight and Let’s Dance Starlight, a compact Hypericum called Sunny Boulevard, Chardonnay Pearls Deutzia, Fine Wine Weigela, Ghost Weigela, and Incrediball Hydrangea. Vanilla Spice™ (Clethra alnifolia ‘Caleb’) is one of our newest introductions and at the moment is only available at wholesale as small liners. If all goes well you will see it at retail in the spring of 2010. Vanilla Spice, like all Clethra, has wonderfully fragrant flowers in late summer. Its foliage is dark, glossy and very attractive. Most remarkably this plant has flowers that are larger than typical. Each flower is roughly 30 to 50% larger than normal.

Vanilla Spice® Clethra

This native beauty is best when planted in a location where you can best enjoy its wonderful fragrance. I like to plant Clethra is large blocks to increase the fragrance potential. Ruby Spice is a special cultivar with reddish-pink flowers, so Vanilla Spice with its white flowers makes a nice companion for this favorite. While white flowers are not as exciting dark pink flowers, I am partial to white flowers. They simply show up better than red in garden, especially in the evening when I am typically in the garden.


Stay tuned, or better yet subscribe to my blog and have it emailed every time I post (Just click here). I will be sharing more new introductions over the next few posts.

Gardening on TV with the Plant Hunter



I just completed a short trip to the East Coast with stops in Rhode Island, Delaware, Pennsylvania and Maryland. The expedition was both interesting and entertaining. I started out in Rhode Island where I was interviewed for the television show Cultivating Life with Sean Conway. It was the first time I met Sean Conway in person so I was pleased to learn that he was more than just a television personality; he’s also an experienced horticulturist, garden designer and nurseryman. Just like me, Sean had a nursery that specialized in rare and hard to find plants. But unlike me, his nursery became a regular destination for magazine editors, authors and style conscious personalities. And unlike me, Sean became a repeat guest on Martha Stewart Living and NBC’s Today show. I, on the other hand, went on to became a guest on Cultivating Life with Sean Conway.

Being on TV is not new to me. I’ve done numerous television appearances, both locally and nationally. I’ve even appeared all of South Korea’s two television stations, so I can tell you from experience that Cultivating Life is first rate production. Sean and his entire production crew are skilled professionals and it was a pleasure to work with them. In TV Land this is not always the case. During a break, I told Sean about my most memorable television experience. It was a live, 30 minute television show and it did not take long to realize I was in big trouble. Five minutes prior to air the host asked me if I was a Master Gardener. When I responded "No", she touched my shoulder and replied in a low, sympathetic voice “I’m so sorry. Don’t you worry; I won’t mention that on the air.” And then, to make matters worse, about halfway into the show she started calling me Tim Cook. I couldn’t believe it. She continued on and on even while the producer frantically waved a big card board sign reading “His name is Tim Wood!!!” How embarrassing is that?

Anyway – if you want to see a first rate gardening show, check out Cultivating Life with Sean Conway. The show’s not live - it’s taped one year in advance - so you won’t get to see Tim Cook, but if you’re lucky you just might catch Tim Wood.


What's Your favorite Gardening Show? Tell me why.

New Plants from Witches' brooms



You can find new plants in the most unusual places and you might be surprised that some are right under your nose. Most likely you pass them by every day and never even notice. Such is the case with Witch's Broom mutations. I found this witch's broom along a busy highway and I’m certain that hundreds of people pass it each day without any notice.

What’s a witch’s broom you ask? They’re point mutations that cause the formation of dense, dwarf growth in an otherwise normal tree or shrub. Horticulturists and plant collectors utilize these mutations to create cultivars such as dwarf conifers and weeping trees. If you root cuttings or graft stems onto seedling rootstock you get a new variety.

Now before get visions of cash and start sending me bags of sticks, I should tell you that most of these types of new plants have already been discovered. There are already a hundred different forms of bird’s nest spruce and we don’t really need another. Sure send me you broom photographs, I’ll be glad to post them, but please don’t send scion wood!

Brooming, the technical term looking for witch's brooms, is a fun and interesting thing to do when hiking a trail or riding in a car. The odds are that if you start looking you’ll find many of these mutations. Some will be high up in the tallest tree while others will be closer to the ground. Joe Stupka, an old brooming buddy from Western Pennsylvania, showed me my first broom back in 1984. We spent the afternoon driving around Mill Creek Park in Youngstown, Ohio and found dozens of interesting brooms. Once you find your first broom the next one is a lot easier. Joe was so broom crazy he would actually breed with brooms. This hobby is not for everyone; it requires lots of time and patience. You rarely find flowers and/or seeds on a broom, but if you grow enough plants and look hard enough it can be done.

The thing I like most about brooming is that it teaches us to look closer at nature and the world around us. Typically we go through life and miss a lot; the miracle of a living tree, the sweet smell of a flower, the community of plants, the diversity of seed and seedlings, the smile of a child, or the tears of someone in pain. But with a little practice, we can learn to notice. And we just might discover a new plant right under our nose, (and a lot of other wonderful things as well).

Have you discovered a witch's broom? Send me a photograph so I can share it with the group.