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Sarah Robertson
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The window above my kitchen sink is the perfect frame for a narrow, arid, south-facing border that runs the length of our neighbor’s newly renovated bungalow.
Reflected sunlight bounces off both the house and a gravel pathway, with nothing nearby to provide even a whiff of shade. The soil is mostly native clay mixed with builder’s sand to encourage drainage near the foundation. The bed itself is scarcely two feet across at its widest point and receives a minimum of water. It could easily be ignored, given its inhospitable location and constricted size.
Instead, this border has become a showcase of fragrance and color thanks to the generous use of plants that thrive in our modified Mediterranean climate of hot, dry summers and fairly wet winters.
Some of the most successful plants in this border are a group of drought-tolerant penstemons. This native American plant family has more than 270 different species. The species are all extremely diverse, with remarkable variations in shape, form and color. There are types that thrive in heat, in moist forests and even at high altitudes. This means that just about anyone, anywhere, can find a penstemon that will grow happily in their garden.
Nearly all penstemons share a love for well-drained soils. This is especially important when growing penstemons in a wet-winter region such as ours, where standing water can kill a plant even faster than subfreezing temperatures.
But once a clump of penstemon is established, it sails through a typical Western Oregon winter. These plants require very little maintenance and, during the growing season, actually resent added fertilizer or irrigation. This group of water-thrifty perennials are an excellent choice for our typically hot, dry and sunny Western Oregon summers.
A single penstemon plant grows as a clump and produces multiple spires of blossoms that range in height from a few inches to several feet. Depending on the species and cultivar, it’s possible to have penstemons in bloom from April through October.
Even with the best of care, penstemons are relatively short-lived. Some species may need to be replaced every three to five years. To get the most from your plants, David Salman, founder of High Country Gardens in Santa Fe, NM, recommends the following cultural considerations:
1. Plant only in well-drained soils; wet clay soils and Penstemon aren’t compatible. Avoid overly enriched soils; too much compost can shorten the life span of these plants.
2. Plant high, leaving the top of the rootball just above the surrounding soil to avoid burying the crown of the plant.
3. Avoid bark, grass clippings or compost as mulch materials. These mulches can cause disease in wet, cold weather. If you must mulch, use pea gravel or something similar that doesn’t compact around the plant.
4. Allow short-lived species to re-seed. The volunteer seedlings will be more vigorous and longer lived than the original parent plant.
5. Fertilize sparingly. Penstemons prefer “tough love” and need just one dose of fertilizer each year in the fall. Choose an organic or natural fertilizer that’s high in trace minerals and phosphorus, but low in nitrogen.
Here are a few penstemon species to consider, courtesy of High Country Gardens (www.highcountrygardens.com; 1-800-925-9387; you can request a free fall catalog, which will arrive the first week in July). All of the following penstemons thrive in hot, sunny conditions and are attractive to hummingbirds:
Praiseworthy Penstemons
• Penstemon cardinalis (cardinal penstemon): This is a seldom grown native of southern New Mexico and west Texas. It grows 2-3 feet tall, 15 inches wide and thrives in the intense sun of the west. The flowers are an unusually deep rich red and hang gracefully off their tall spikes. Blooms in midsummer and is a great species to help keep the hummingbirds around your yard. Attractive large deep green leaves. A fantastic variety! Zones 5-9.
• Penstemon pinifolius (pineleaf penstemon): An outstanding but often overlooked species from southern New Mexico and Arizona. Grows 15 inches tall by 18 inches wide. Blooms for six to eight weeks in midsummer, producing profuse numbers of tubular orange flowers. This is a fairly long-lived penstemon that grows easily in both xeric and traditional perennial gardens. As the plant matures, the stems become woody, forming an attractive evergreen shrublet with bright green needle-like foliage. Zones 4-9.
• Penstemon pinifolius 'Mersea Yellow' (yellow pineleaf penstemon): This unusual color variant (or “sport”) was discovered in an English garden in 1980. Hundreds of soft yellow tubular flowers cover the plant for many weeks in midsummer. This plant does appreciate a little extra water, and can be grown in both lean and enriched garden soils as long as the drainage is good. Needs afternoon shade in hot desert climates. Yellow Penstemons are a great rarity in this huge genus.
• Penstemon strictus (Rocky Mountain penstemon): A native of the foothills and mountains of the southern Rockies, this 2-foot tall, 3-foot-wide plant produces showy spikes of intense blue-purple flowers that last for over a month in late spring. Spreading steadily via stolons to form large clumps, Penstemon strictus is one of the longest lived, most easily grown of the Penstemons. A real show stopper!
• Penstemon 'Red Rocks' ™: This lovely 2-foot tall, 15-inch wide hybrid is a 1999 Plant Select® winner. Developed by Bruce Meters, “Red Rocks”™ is named after Denver’s famous amphitheater which was carved out of the spectacular red sandstone cliffs in the foothills west of the city. This hybrid has glossy, narrow foliage and tall spikes of stunning rose-pink and white flowers. This is a vigorous grower that performs best in moderately fertile, but well-drained soils. Though xeric, “Red Rocks”™ will flower most vigorously with regular watering. Zones 5-9.
Sarah Robertson is a Eugene-area writer who studied horticulture at Oregon State University and practices a "trial and error" approach to home gardening.
Reflected sunlight bounces off both the house and a gravel pathway, with nothing nearby to provide even a whiff of shade. The soil is mostly native clay mixed with builder’s sand to encourage drainage near the foundation. The bed itself is scarcely two feet across at its widest point and receives a minimum of water. It could easily be ignored, given its inhospitable location and constricted size.
Instead, this border has become a showcase of fragrance and color thanks to the generous use of plants that thrive in our modified Mediterranean climate of hot, dry summers and fairly wet winters.
Some of the most successful plants in this border are a group of drought-tolerant penstemons. This native American plant family has more than 270 different species. The species are all extremely diverse, with remarkable variations in shape, form and color. There are types that thrive in heat, in moist forests and even at high altitudes. This means that just about anyone, anywhere, can find a penstemon that will grow happily in their garden.
Nearly all penstemons share a love for well-drained soils. This is especially important when growing penstemons in a wet-winter region such as ours, where standing water can kill a plant even faster than subfreezing temperatures.
But once a clump of penstemon is established, it sails through a typical Western Oregon winter. These plants require very little maintenance and, during the growing season, actually resent added fertilizer or irrigation. This group of water-thrifty perennials are an excellent choice for our typically hot, dry and sunny Western Oregon summers.
A single penstemon plant grows as a clump and produces multiple spires of blossoms that range in height from a few inches to several feet. Depending on the species and cultivar, it’s possible to have penstemons in bloom from April through October.
Even with the best of care, penstemons are relatively short-lived. Some species may need to be replaced every three to five years. To get the most from your plants, David Salman, founder of High Country Gardens in Santa Fe, NM, recommends the following cultural considerations:
1. Plant only in well-drained soils; wet clay soils and Penstemon aren’t compatible. Avoid overly enriched soils; too much compost can shorten the life span of these plants.
2. Plant high, leaving the top of the rootball just above the surrounding soil to avoid burying the crown of the plant.
3. Avoid bark, grass clippings or compost as mulch materials. These mulches can cause disease in wet, cold weather. If you must mulch, use pea gravel or something similar that doesn’t compact around the plant.
4. Allow short-lived species to re-seed. The volunteer seedlings will be more vigorous and longer lived than the original parent plant.
5. Fertilize sparingly. Penstemons prefer “tough love” and need just one dose of fertilizer each year in the fall. Choose an organic or natural fertilizer that’s high in trace minerals and phosphorus, but low in nitrogen.
Here are a few penstemon species to consider, courtesy of High Country Gardens (www.highcountrygardens.com; 1-800-925-9387; you can request a free fall catalog, which will arrive the first week in July). All of the following penstemons thrive in hot, sunny conditions and are attractive to hummingbirds:
Praiseworthy Penstemons
• Penstemon cardinalis (cardinal penstemon): This is a seldom grown native of southern New Mexico and west Texas. It grows 2-3 feet tall, 15 inches wide and thrives in the intense sun of the west. The flowers are an unusually deep rich red and hang gracefully off their tall spikes. Blooms in midsummer and is a great species to help keep the hummingbirds around your yard. Attractive large deep green leaves. A fantastic variety! Zones 5-9.
• Penstemon pinifolius (pineleaf penstemon): An outstanding but often overlooked species from southern New Mexico and Arizona. Grows 15 inches tall by 18 inches wide. Blooms for six to eight weeks in midsummer, producing profuse numbers of tubular orange flowers. This is a fairly long-lived penstemon that grows easily in both xeric and traditional perennial gardens. As the plant matures, the stems become woody, forming an attractive evergreen shrublet with bright green needle-like foliage. Zones 4-9.
• Penstemon pinifolius 'Mersea Yellow' (yellow pineleaf penstemon): This unusual color variant (or “sport”) was discovered in an English garden in 1980. Hundreds of soft yellow tubular flowers cover the plant for many weeks in midsummer. This plant does appreciate a little extra water, and can be grown in both lean and enriched garden soils as long as the drainage is good. Needs afternoon shade in hot desert climates. Yellow Penstemons are a great rarity in this huge genus.
• Penstemon strictus (Rocky Mountain penstemon): A native of the foothills and mountains of the southern Rockies, this 2-foot tall, 3-foot-wide plant produces showy spikes of intense blue-purple flowers that last for over a month in late spring. Spreading steadily via stolons to form large clumps, Penstemon strictus is one of the longest lived, most easily grown of the Penstemons. A real show stopper!
• Penstemon 'Red Rocks' ™: This lovely 2-foot tall, 15-inch wide hybrid is a 1999 Plant Select® winner. Developed by Bruce Meters, “Red Rocks”™ is named after Denver’s famous amphitheater which was carved out of the spectacular red sandstone cliffs in the foothills west of the city. This hybrid has glossy, narrow foliage and tall spikes of stunning rose-pink and white flowers. This is a vigorous grower that performs best in moderately fertile, but well-drained soils. Though xeric, “Red Rocks”™ will flower most vigorously with regular watering. Zones 5-9.
Sarah Robertson is a Eugene-area writer who studied horticulture at Oregon State University and practices a "trial and error" approach to home gardening.
