Gold Medal Award-Winning Plants
The Pennsylvania Horticultural Society's picks for great plants for the mid-Atlantic region...and beyond!
The Pennsylvania Horticultural Society (PHS) has shared its list of 2024 Gold Medal Plant winners, now available to the public through most garden retailers. The Gold Medal Plant Program was created by PHS in 1979 to celebrate and showcase beautiful, easy-to-grow plant species, that are ideal for home gardening. Each year, a committee of horticulture experts convenes to assess trees, shrubs, and perennials on various criteria including their suitability for home gardens in the mid-Atlantic region, their ease of cultivation, ready commercial availability, wildlife value, weather tolerance, and pest resistance.
Since the program’s inception, PHS has named over 150 Gold Medal Plants. Including this year’s winners, all plants are indicated for their hardiness in zones 4 to 8 on the USDA’s hardiness zone map, making them ideal choices for the Mid-Atlantic region.
“The PHS Gold Medal Plant program provides amateur and professional gardeners alike with unique plant species suggestions to help refresh their gardens with easy-to-grow, hardy perennials, trees, shrubs, and edibles, many of which also bring ecological function to the garden and benefit local wildlife.” said Andrew Bunting, PHS’s Vice President of Horticulture. “This year’s Gold Medal Plant winners provide a wide array of plant recommendations that are well-suited to many different types of garden spaces, making it simple to find a plant that is right for your garden’s conditions.”
To learn more about this year’s Gold Medal Plants, or to view previous year’s winners in PHS’s online database, visit: phsonline.org/for-gardeners/gold-medal-plants.
Whoa. Don’t close this email if you garden in USDA Zones 9 and 10. Or for that matter, chilly Zone 3. Some of these Gold Medal Plants are worth are try in areas of the country that are warmer or colder.
Here are the six Gold Medal Plants that we discussed with the PHS’ Vice President of Horticulture, Andrew Bunting, on Episode 323 of the Garden Basics Podcast.
Four viewpoints are expressed for each plant:
• The Pennsylvania Horticulture Society’s PR Department (PHS);
• Andrew Bunting, VP of Horticulture for the PHS (AB);
• An outside expert, such as a University Cooperative Extension review of the plant, a plant producer, or plant distributor.
• And, my own snarky thoughts. (FF)
Asparagus ‘Millenium’
PHS: Edible
"One of the highest yielding asparagus on the market, Asparagus officinalis ‘Millennium’ is a stem vegetable that produces uniform, tight tipped, tender spears with excellent flavor. It is hardy and easy to grow. It prefers full sun and loose, organically rich, evenly moist, sandy, well-drained soil. In addition to the edible shoots, asparagus produces attractive ferny foliage that turns yellow in the fall before going dormant in winter. Asparagus officinalis ‘Millennium’ grows up to 3-5 ft. tall and 1-3 ft. wide. It is disease, deer, and drought resistant and grows in hardiness zones 3-10.”
AB: “We thought it was important for us to add a new category to the Gold Medal Plants. We added an edible category. And we also added a couple of experts to the panel whose knowledge base is in the edibles. So the way a plant makes it to the list is it has to be nominated, then the committee answers a survey. And whichever ones go to the top of the list, this being one of them, are then are considered against other top nominees. And so asparagus ‘Millennium’ got in. It's an asparagus that is really good for production, good taste, easy to grow. In general, asparagus is relatively easy to grow. It's a crop that people don't often grow, because it takes a while for it to mature and get to a state where you can have an appreciable harvest.”
North Dakota State University: ‘Millennium’ has emerged as the top choice of asparagus varieties in the Midwest. For several years, University researchers have recommended the “all-male” hybrids from Rutgers, including ‘Jersey Giant’, ‘Jersey Knight’ and ‘Jersey Supreme’. Walker Brothers, the producer of ‘Jersey’ asparagus crowns, has stopped propagating them. Retailers may have a limited supply of ‘Jersey’ varieties in stock, but we need to find an alternative in the long run.
‘Millennium’ looks outstanding. It’s high yielding, long lived, cold hardy, and adaptable to a wide range of soils.
Bred in Ontario, ‘Millennium’ has been grown successfully in Minnesota for several years. Trials conducted in 2013 in northern Minnesota showed it produced 2,094 pounds per acre compared to 1,287 pounds for ‘Jersey Giant’ and 1,233 for ‘Jersey Knight’.
Research in Michigan found plantings of ‘Millennium’ were slower to attain high yields compared to ‘Jersey’ varieties, but they later showed superior and heavy yields over a 15-year lifespan. Plantings show greater vigor and survival.
The yield advantage of ‘Millennium’ may be in part because it has a higher proportion of male plants compared to the ‘Jersey’ varieties. Male plants are desired because their energies are more focused on producing spears. Female plants spend part of their energy forming seeds. These seeds later drop, causing the bed of asparagus to get overcrowded and the spears to get smaller.
Large scale plantings in Michigan indicates ‘Millennium’ is better adapted to cold climates compared to ‘Jersey Giant’ or ‘Jersey Supreme’. It goes dormant earlier in the fall and emerges later in spring, reducing the risk of frost damage. ‘Millennium’ is hardy throughout our state.
‘Millennium’ may be managed to reduce populations of asparagus beetles. Ferns that go dormant earlier in fall can be cut earlier, reducing the likelihood of asparagus beetles from overwintering in the debris.
‘Millennium’ has shown the ability to grow well in a wide range of soil types, including heavy soils.
‘Millennium’ shows intermediate resistance to rust, the most damaging disease in asparagus plantings.
Traditional open-pollinated lines such as ‘Mary Washington’, ‘Martha Washington’ and ‘Purple Passion’ are still available. These varieties have a much higher percentage of female plants. They are less productive, and their spears are less uniform in size compared to those of hybrids.
Hybrids developed in California do not have the hardiness and vigor we need in North Dakota.
Gardeners typically start asparagus plantings using 1-year-old roots. A light harvest is available in the second year, a larger harvest the third year, and a full harvest thereafter.
FF: They really like this asparagus variety there in North Dakota. In their review of the Asparagus ‘Millenium’ they had sort of a snotty remark about California. But being that my mother's family is from North Dakota, I'll allow this one. North Dakota University says “hybrids developed in California do not have the hardiness and vigor we need in North Dakota”. Well, since they didn’t ask, one UC Davis-developed variety of asparagus that does well is UC-157. It succeeds where ice fishing is a rarity, in USDA Zones 6, 7, 8 and 9. It is an “early, high-yielding hybrid, the plant produces an abundance of long, straight, light green spears with tight, tapering tips and a delicious super sweet flavor.” That’s according to Park Seed. They wouldn’t exaggerate, would they?
Magnolia ‘Genie’
PHS: This tree is a perfect choice for small space gardens. It has an incredible spring flowering display of red to purple scented flowers that are eye-catching; long-lived and easy to care for with repeat blooms through the growing season. Its narrow columnar form fits anywhere and can be grown in an extra-large container. Plant Magnolia ‘Genie’ in sun to part shade in slightly acidic, moist, fertile, well-drained soils. Amend with compost when planting and keep well-watered. It reaches only 10-13 ft. Tall and 5 ft. wide. It is hardy in zones 5-8.
AB: “Its real claim to fame is that it's fairly diminutive in its stature. It only gets about 12 feet tall at maturity. It does have kind of saucer magnolia-like flowers. However, they're pretty intense, deep, dark, purple. So that's a little bit of a departure from your typical saucer magnolias. For somebody who's looking for something that has a strong kind of Magnolia-like flower power, but doesn't have the room for some of these bigger flowering magnolias, then Genie is perfect. It'd be perfect for like a courtyard garden. Perfect for a city dweller that maybe has a small backyard but still wants to have a magnolia. Then this is a good choice.”
Monrovia Plants: “This small, pyramidal tree is the perfect way to bring dramatic spring blooms into a small garden. Stunning, deep maroon-purple buds open to lightly fragrant pink flowers on bare branches in early spring, holding, as the green leaves emerge, until early summer. Blooming repeats in late summer. A wonderful accent in shrub borders or next to patios.”
FF: “I know that Monrovia grows that plant here in California and they say that it's good from USDA zones four through nine. And I've heard from enough people in USDA zone nine that I know it does well and looks fabulous here. And like you say, it is diminutive, maybe 10 to 13 feet tall and five feet wide.”
The Florida Anise Tree - Illicium ‘Woodland Ruby’
PHS: ‘Woodland Ruby’, commonly known as Florida anise tree, has deep reddish strap-like flowers creating an extended period of bloom beginning in early summer and lasting through fall. It requires protection from winter winds and is happiest in some shade but will tolerate more sun given enough moisture. It grows well in numerous settings and especially well in city gardens, where space and light are issues. It is deer resistant, attracts pollinators, and is fragrant. In its mature height of 6-7 ft., it is a good choice for a screen or backdrop. It is hardy in zones 6-9.
AB: “The Illiciums are a plant that 15 years ago, hardly anybody knew about them. There are some Mexican natives, but this one is derived from a Florida native and it's a broadleaved, evergreen that reaches five to 10 feet tall. The leaves smell like anise and because of that, the deer don't like them. This is truly deer resistant. There are many plants you can make that claim with, but Illicium ‘Woodland Ruby’ is one of them.”
North Carolina Cooperative Extension: Illicium ‘Woodland Ruby’ is a hybrid cross between I. floridanum ‘Alba’ and I. mexicanum. This rounded shrub or small tree produces large, vibrant purple-red to rose-pink flowers from spring into fall. Anise-scented evergreen leaves and a mature height and width of 8 feet make it an excellent choice as a specimen or a hedge in shade or part shade. Because the plant is not particularly winter hardy and should be protected from winter winds, it can also be grown in containers and brought indoors over winter.
While 'Woodland Ruby' grows best in partial to full shade, it can tolerate sun if it is well watered. Organically rich soil should be kept moist and extra irrigation applied during prolonged dry spells, as it has a tendency to wilt. Established plants, however, are drought tolerant. The recommended USDA zones range from 7 to 10. Plants can be trimmed to control height.
Diseases, Insect Pests, and Other Plant Problems: No known diseases or insect pests.
FF: “The University of North Carolina has this warning about the Illicium ‘Woodland Ruby’. It says this plant has high severity poison characteristics. It talks about its fruits, leaves and seeds being the poisonous part. And the principal toxin - and I'm going to mangle this name - is sesquiterpene lactones - and I have no idea what that is. But, I grew up around oleanders and I lived.” Keep the plant away from livestock, however.
‘Sugar Shack’ buttonbush - Cephalanthus occidentalis ‘Sugar Shack’
PHS: “This selection of buttonbush is a more compact version of native Cephalanthus and good for small space gardens. Its fragrant, white, globe-like flowers are prominent in the summer and followed by burgundy foliage in the fall and red fruit in the winter. It is easily grown in moist, humus soils in full sun to part shade. Cephalanthus attracts a variety of pollinators and can grow to 5 ft. tall and wide at maturity. It is hardy in zones 4-8.”
AB: “If people aren't familiar with a buttonbush, you'll find it all throughout the east and southeast, often growing in standing water. So not only is it a good native, it's a good plant for marshy or wet areas in the yard. So there are many plants that can actually thrive in actual standing water. This is one of them. It's also produces these really interesting white, globe-like flowers that are fragrant. Great for attracting pollinators, especially butterflies. Also it’s really hardy, so this could grow anywhere on the east coast, but also into the Midwest and upper midwest, as well. And then it gets a decent fall color, a burgundy fall color also.”
Proven Winners: “Great for rain gardens! Buttonbush has long been prized as a native, but it was way too big for most landscapes. Not anymore! We've cut the size in half and added colorful red fruit and glossy foliage. Add in cool looking, fragrant white flowers and you've got a delightful plant that shines from spring to fall.”
FF: “I had to look up the term, ‘Sugar Shack’ to see where it came from, other than being, of course, the Jimmy Gilmer and the Fireballs song of 1963 which was a song about a beatnik coffee shop. But a sugar shack, if you're live in an area where you grow maple trees and you harvest the sap, the Sugar Shack is the small cabin where you boil the 40 gallons of sap into one gallon of maple syrup. However, the Urban Dictionary has a more colorful description of the term, “Sugar Shack”.
The Japanese Roof Iris - Iris tectorum
PHS: “The common name for Iris tectorum is Japanese roof iris. It grows well in organically rich, medium moist, well-drained soil in full sun to part shade. It benefits from the shelter of a wall with western or southern exposure and winter mulch. It has beautiful showy flowers in shades of lavender blue, blush violet, and blue lilac. Its foliage is arranged in fans of narrow, lance-shaped, ribbed, glossy, upright leaves. It can spread rapidly in the garden. It is deer resistant and grows 12-18 inches tall in maturity. It is hardy in zones 6-9.”
AB: “In Swarthmore PA, there's a nationally known gardener, Charles Cresson. So it's kind of odd, you walk up to the front of his house, and he has this little outdoor porch with a roof. And growing on the roof is this iris, that grows 12 to 18 inches tall. Kind of an oddity. So this Japanese Roof Iris can also grow in either gravelly areas, rocky areas, and it can grow in regular garden soils, as well. But if you have a site where it's totally impoverished, soil or soilless, like a roof, it can grow in those conditions.”
North Carolina Cooperative Extension: This interesting member of the crested iris group is beardless, but the falls are marked by a fringed crest of white on purple. Japanese roof iris are an example of the great diversity of exotic Iris species coming into the nursery industry with varied colors and flower formations. Though the bloom is large at 6 inches, the standards are shortened and tubular and the falls widespread. The leaves are 15 inches tall, fanned at the base and ribbed. The rhizomes should be spaced 10-16 inches apart, planted at 1-2 inches deep, and will mature at soil level. They prefer a sunny to part-shade location in rich, well-drained soil and benefit from the shelter of a wall with western or southern exposure and winter mulch. Japanese roof iris is also useful in wet areas, such as around ponds and fountains. But they do not require a great deal of water so they can be used in rock gardens. As the rhizomes spread, this iris can be used for naturalizing and mass planting. The common name is derived from the historical use on thatched roofs in its native China and Japan. These iris tolerate drought and deer. Prone to slugs and viruses. Infected plants with darkened leaves should be removed and destroyed. The seeds do not harbor the infection.
FF: A roof? That seems like a good place for an iris.
Foamflower “Brandywine” - Tiarella cordifolia ‘Brandywine’
PHS: ‘Brandywine’ foamflower is an early season, long blooming, native perennial introduced by Sinclair Adams at Dunvegan Nursery in West Chester, PA. It thrives in part to full shade and works well in both dry and moist soils. The leaves have red hues and turn bronze in the fall. Its lovely spiked white flowers sit above the ground-hugging foliage and stay in bloom for 2 months. It attracts specialist bee species and other pollinators, and it is great for small space gardens, containers, and window boxes. It combines well with other shade-loving plants. It is deer resistant and grows to be 8-18 in. tall when in flower. It is hardy in zones 4-8.
AB: “I love the foamflowers. It's one of my most favorite spring flowering plants. Tiarella cordifolia is an East Coast native, and ‘Brandywine’ was a clump forming perennial with these little spikes resembling white bottlebrush. Flowers in April, maybe into May, the leaves are kind of rounded, slightly scalloped and have kind of red and bronzy color in the fall. It’s great for colonizing and shady spots. It can also take a little part sun as well. So it's a fairly versatile and a long lived perennial whether you use it in the woodland garden or kind of an accent in a in a shade garden.
Missouri Botanical Garden: “Easily grown in average, medium, well-drained soil in part shade to full shade. Prefers humusy, organically rich, moisture-retentive soils. Soil should not be allowed to dry out. Wet soils, particularly in winter, can be fatal, however. Removal of flower spikes after bloom will improve the appearance of the foliage mound. Foliage is semi-evergreen in the St. Louis area where the amount of retained foliage color in winter, if any, is in large part dependent upon the severity of the temperatures.”
FF: I noticed that the Missouri Botanical Garden states that it's adaptable from zones four through nine, which means it has a chance here in California, in the shade.
Thank you for also listening to the Garden Basics with Farmer Fred podcast! It’s available wherever you get your podcasts. Please share it with your garden friends.
Fred Hoffman is also a University of California Cooperative Extension Master Gardener in Sacramento County. And he likes to ride his bike(s).