|
FrontRangeLiving.com -> Garden -> Penstemons
 In Praise of Penstemons
As the rocky soil around the Hayman fire healed, an assortment of native
plants sprouted. One bright blue penstemon took the lead.
Penstemon glaber, the color
of lapis lazuli, joined yuccas, grounsels and wild roses. The penstemon spread
more quickly and thickly than nearly any other wildflower.
Penstemons, a
spectacular collection of mostly Western wildflowers, have jumped fences from wild
to mild, settling into drought-tolerant landscapes. Gardeners love their
brilliant colors, tough natures and unkempt appearances.
These wildflowers do have exacting needs. Some, like glaber, thrive
on disturbed soil of a recent burn. Others will take to regular garden soil a
little more easily. Penstemons include hybrids, which are what you'll most likely find at garden centers, bred to be a certain
height and color. Some are perennial in Colorado but not all. Many of the most striking,
long-lived and drought-tolerant often are native species plants, exactly as Mother
Nature designed. The key to including them into a garden is to match soil, site
and penstemon.
 Rocky Mountain penstemon, Penstemon strictus, shows up at garden centers on
the natives table, closely related to Penstemon glaber. Although it’s found west of the Front Range in its native
habitat, this penstemon adapts readily to ordinary garden soil providing the
gardener keeps it a bit on the dry side. Even if it’s over-watered, too much
saturation is more likely to shorten the life span of the plant rather than kill
it outright.
An added boon is that Rocky Mountain Penstemon grows reliably from seed. Like most penstemons,
a cold period is required for germination. This mimics the natural world.
Penstemons produce seed at the end of summer. The seeds winter over protectively
under snow and only germinate after a period of time, usually 40 days. By then,
providing there’s moisture via late snows, the seed will germinate and send
out roots and a slender tendril. Nearly every package of purchased penstemon
seeds will state the stratification, or cold-requiring days for germination.
 Every penstemon gardener I’ve met has a different method for
stratification. Some sow the seeds in cement troughs that can take winter
temperatures. They’ll fix a mix of soil and sand--the perfect combination for
penstemons that like gritty soil. A pile of snow atop keeps moisture in. Then
the gardener waits until spring, never allowing the soil to dry out completely.
I’ve tried this and I’m sure it works providing you dutifully remember to
attend to the trough from time to time. But as my attention wanders, I usually
fail to keep the seeds moist and germination never takes place.
So I’ve reverted to the refrigerator method. I dampen a paper towel,
sprinkle in the seeds, roll the towel up and store it in a plastic bag that has
been labeled. Then I place it in the refrigerator and wait. Every now and then, as I
ferret around the vegetable bin for lettuces, I
check the seeds. For weeks, there’s no change. But if the towel has dried, I’ll
dampen it a bit. After 40 or so days, a green shoot emerges. One by one, the
viable seeds germinate within a few days of each other. They’re ready to be
potted in seedling soil without added fertilizers.
 I like to grow natives in a tall seedling pot or a wider pot with room for a
taproot. Too often a spindly native plant that’s drought tolerant sends down a
formidable root that winds round and round, root bound too early in its seedling
life. I mix damp seedling soil with some sand, just enough to give a bit of grit
for drainage. Then I place the germinating seed in the soil, cover it with a lid
of some kind and let the moist environment contribute to seedling growth.
By the time the penstemon’s true leaves appear, I’ll fertilize with a
weak solution of fertilizer mixed in water. Few penstemons care much for
fertilizer, so one-quarter strength or less will do. Keep the penstemons under
lights when they are very young. But as soon as they grow an inch or more, I get
them outside when temperatures rise to about 50 degrees by midday for full-strength sun. This is what they like best,
although most will accommodate a interior light arrangement if need be. Most
penstemons will develop sturdy roots and stems as they are tossed about by the
wind, heated up by the sun and cooled off by a sudden temperature shift. Bring
them in by the late afternoon. By early May, they can go into the garden.
Find a spot where you can water them regularly the first of the season. By
summer, they’ll be on their own, ready for little water but enjoying full sun.
The tall spires look best with other wild looking plants—ornamental grasses,
daisies and sunflowers. Come fall, you can harvest the dried seeds and try
growing your own seeds when mid-winter arrives.
 Many penstemons won’t be as compliant as the Rocky Mountain penstemon. They
need a particular kind of gritty soil, or weather conditions. They’ll hate
your garden soil and curl up at a drop of water. But trial and error will tell
you what flourishes for you. And once you learn to grow them from seed, you can
experiment for the cost of a few dollars. Penstemon barbatus, or iron maiden
penstemon, is a top choice. So is Penstemon
secundiflorus.
Penstemon eatonii, or firecracker penstemon is worth a try.
Penstemon pinifolius, or pineleaf penstemon, is a favorite of garden centers, too. And if
you have a garden that is filled with ornamentals that have high water needs,
'Husker Red' penstemon, (Penstemon digitalis) which hails from the East Coast, is a better choice. Few
penstemons will accept heavy watering the way 'Husker Red' will.
If you can grow lavender, Russian sage or agastache, you can grow most
penstemons. Eventually, the only difficulty may be in deciding how many to
choose. Start with Rocky Mountain penstemon and go from there. Plant it in that
rocky, sandy or gravelly part of the garden that is sun drenched and watch it
flourish.
Photos: from top to bottom, Penstemon glaber at the Hayman burn,
Rocky Mountain penstemon to the left, pineleaf penstemon to the right (Penstemon
strictus, Penstemon pinifolius) in a Front Range garden, Whipple's penstemon (Penstemon whippleanus
found in subalpine to alpine altitudes), Hall's penstemon (Penstemon halli,
found in subalpine to alpine altitudes), sidebells penstemon (Penstemon
secundiflorus)
|
