Fabulous Fall Grasses

What do we plant for fall color? Most of us would quickly list off maples and crabapples, or perhaps a burning bush (aka winged euonymus). But what about grasses? Some ornamental grasses have impressive fall foliage, and it lasts all winter.

Ornamental grasses are everywhere. What was once a fairly obscure group of landscape plants have emerged into the spotlight, and their popularity shows no sign of fading. That’s not surprising, considering how much they have going for them—flowing leaves, towering seed heads, a fountain shape unlike that of shrubs or perennials that adds contrast and texture to the garden.

(more…)

Presenting Autumn, Starring Rabbitbrush!

Chrysothamnus nauseosus_Rabbitbrush_Cylindropuntia_Cholla_ChicoBasinRanch-CO_LAH_2989-001With intense sulfur-yellow flowers covering its gray-green foliage, blooming Rabbitbrush demands to be noticed. In fact, the prairies of eastern Colorado are almost blanketed with it—something we never notice until it blooms. Interspersed with prickly cholla cactus and some perennial range grasses, it forms the essence of western landscapes. But it’s not just for the wide open spaces. Rabbitbrush is an excellent performer in the garden as well.

(more…)

September is for Rudbeckias

Rudbeckia - Black-eyed Susan_XG_20090826_LAH_9669Summer ends this weekend, but late-blooming flowers are far from finished. One can’t help but notice the conspicuous school-bus-yellow daisies, known as Black-eyed Susans, which thrive along our Colorado roadsides. (Most are Rudbeckia hirta, but other species also grow here.) Happily for us gardeners, there are cultivated forms of Rudbeckia that continue to brighten our home landscapes well into autumn.

(more…)

Plant Quiz Answers

DBG_LAH_1264If you haven’t tried to identify the plants in my quiz, back up to last Thursday and try your hand before reading any further.

So, how did you enjoy trying to ID various random plants from a photo or two? I think it’s fun, which is why I love my job. Sometimes I know the answer off the top of my head (number 1, for example) while others have me tearing my hair out while I track them down (such as number 8).

(more…)

Blue Mist Spiraea

Caryopteris clandonensis_Bluemist Spirea_XG_ColoSpgs-CO_LAH_5819Spring flowers have turned into berries and seed pods. Without their blossoms peonies are mere green bushes, and even the annuals are looking a bit peaked. Don’t despair, however. The show isn’t over yet. One of the best perennials (or small shrubs) for Colorado gardens is Caryopteris x clandoensis, more familiarly known as Bluebeard or Blue Mist Spiraea.

The latter common name can cause some confusion. Caryopteris isn’t a true spiraea. The “Blue Mist” part is spot on. The airy flowers in periwinkle blue really do seem to hover over the tips of the stems in a lovely cloud. The plants can reach two to three feet wide and tall. Foliage is a bluish gray-green, with long, soft, serrated leaves.

(more…)

Delphiniums

Delphinium_ColoSpgs-CO_LAH_4854-001Most people recognize Delphiniums in the cottage garden. With their tall spikes of vibrant blue (or red, pink, rose, white, orange, or purple) flowers, nothing else is quite like them. Huge delphiniums are a staple in England, where cool temperatures and fog provide a perfect environment. But I despaired of having these heavenly blue blossoms in my Colorado garden. It’s just too hot and dry.

Colorado gardeners do manage to grow spectacular hybrid Delphiniums, but as one Colorado master gardener put it, a delphinium is

“… one of the neediest perennials ever. It likes sun but not in the hottest part of the day. It needs even moisture, mulching and careful watering. It reacts poorly to extremes of heat and cold, and requires a lot of fertilizer. To top all that, it requires its devoted fans to cut it back immediately after early-summer flowering before it will even consider reblooming a full three months later. (Many years, early June bloom is all you get, given the extreme pickiness of this flower.) Finally, unless it really, really likes its location, it may never be seen again after that September curtain call.”

Delphinium @CSUtilXeriscapeGarden 9Aug2006 LAH115I’m not that dedicated to fussing over a particular plant, no matter how gorgeous, which is why I was delighted to discover that the familiar, tall Delphinium grandiflorum isn’t the only kid on the block. Other cultivars and species are much better adapted to our challenging conditions.

Blue Butterflies (right) is a cultivar of D. grandiflorum, but you’d never recognize it. Growing only one to one-and-a-half feet high, these bushy plants are covered with purple-blue flowers that are more open than the Giant Pacific Hybrids. Instead of big leaves, the foliage is finely divided, giving it a lacy look. You still need to provide moist, rich soil, and they need to be deadheaded, but at least they survive a windy day much better than the staked varieties. My Blue Butterflies did eventually die, but it lived for several years without any special attention on my part. I was impressed.

Delphinium_exaltatum wikicommonsDelphinium exaltatum  (left, photo courtesy of Wikicommons) is a perennial species native to the eastern U.S. As you might expect, it must be kept constantly moist, but it tolerates Colorado’s lime soils. Plant in morning sun or bright shade (it needs full sun where skies are often overcast) and provide protection from strong winds. Fertilize regularly. As they fade, remove the flower spikes to encourage additional bloom (maybe). You can buy seedlings or start your own; a cold treatment is needed for germination.

Delphinium x belladonna is another hybrid perennial that is easier to grow. It prefers full sun, well-drained soil with high fertility (amend, amend!), and shelter from strong winds. It’s a good idea to stake the tall flower spikes. This delphinium originated in Europe. It’s best to buy transplants.

Delphinium hyb_BFAlpineGarden-Vail_LAH_4851-001We haven’t mentioned pests and diseases yet, but there are plenty of both. Delphiniums are susceptible to powdery mildew, southern blight, root and crown rot, botrytis blight, fungal and bacterial leaf spots, white rot, rust, white smut, leaf smut, and damping off. Slugs love them, although that’s not a huge problem in Colorado. They also get cyclamen mites, borers, and leaf miners. To top it off, all parts of Delphinium plants are poisonous; even handling the plants can cause skin irritation.

Given the difficulty of growing your own, perhaps a better solution is to enjoy the delphiniums that Mother Nature grows. An easily-recognized wildflower (it’s the tall, blue or purple one), most wild delphinums are annuals, and are referred to as Larkspur. The Colorado Rockies offer several species. One good location is Crested Butte in mid-July, or try Yankee Boy Basin above Ouray (4-wheel drive needed).

The Perfect Purple Pea Plant

Baptisia australis_Flase Indigo_HAS-CoSpgsCO_LAH_0247I fell in love with Baptisia australis (aka Blue False Indigo) the first time I saw it in full bloom at the Denver Botanic Gardens. Then again, I do have a “thing” for purple flowers (which probably explains the profusion of cat mint, May Queen sage, and Veronica growing in front of our house).

Baptisia is a perennial; the plants die back to the roots after the first freeze. However, come spring the plants quickly grow into attractive mounded shrubs about three to four feet in diameter. If that is too large for your space, there’s a dwarf form that only reaches half that size. (more…)

Pretty in Purple

LAH_2023Thank heaven for spring bulbs! Just when I can’t bear another day of bleak winter landscape, leafless branches, dried and disintegrating foliage—along come neon-bright crocuses, dancing daffodils, and my favorite, luscious purple grape hyacinths. Not true hyacinths (which are borderline hardy in my 7,000 foot high garden), grape hyacinths are also sold under their genus Muscari. They’re native to southeastern Europe, and are widely cultivated for their early spring flowers in pink, purple, white, or a two-toned combination. (more…)

True Blue

Papaver_Blue Poppy_LakewoldGardens-WA_LAH_0564_fsLike many gardeners, I have a “thing” for blue flowers. Lobelia (below), Blue Mist Spiraea, cornflower (Bachelor’s Buttons), and Borage all find a spot in my garden. I’d love to include Himalayan Blue Poppies, hydrangeas, and morning glories but they don’t do as well in my soil and climate. (The poppies need constantly damp soil, hydrangeas need acidic soil to turn them blue plus they’re not hardy enough. The morning glories do well in my greenhouse, but outdoors they usually freeze before them get around to blooming.)

(more…)

Clean-shaven Irises

Iris hyb_XG-CO_LAH_6240Colorado gardeners are so familiar with Bearded Irises (Iris germanica) that we tend to forget there are any others. It’s true that Bearded Irises do exceptionally well in our climate and soils, but they won’t bloom for several more months. Two smaller relatives—Iris reticulata and Iris danfordia—are blooming now. Why not grow them as well?

Iris reticulata and I. danfordia are collectively known as Dwarf Irises. You may also see them labeled miniature irises or rock garden irises. Iris danfordia is a sunny yellow with brown specks; I. reticulata comes in shades of blue, purple, lavender, maroon, white, and yellow. It has bright yellow and/or white markings on the petals. This species has a number of named cultivars, including ‘Harmony’ (deep  cornflower blue) and ‘J.S. Dijt’  (very deep purple). All the photos on this page are I. reticulata. (Hybrid irises typically sold as “Dutch Iris” are larger, and bloom later in the summer.)

(more…)