Category Archives: Xeriscaping

Pretty Tough Plants Book Review

I love the name of the new book by the experts at Plant Select. Pretty Tough Plants describes the family of Plant Select plants perfectly.

If you’ve grown any of these beautiful plants that are so well-suited to our gardens, then you know what I mean. If you haven’t grown any Plant Select recommendations, what’s stopping you? These are the plants that can help you be a more successful gardener.

Plant Select calls itself “a nonprofit collaboration of Colorado State University, Denver Botanic Gardens, and professional horticulturists.” I call it one of the best plant testing and introduction programs in the country.

Pretty Tough Plants: 135 Resilient, Water-Smart Choices for a Beautiful Garden (Timber Press, 2017) is a follow-up to Durable Plants for the Garden: A Plant Select Guide published in 2009.

This new edition seems to be more user friendly, both by its manageable size and in the plant presentations. Plants are divided into groups that include tender perennials and annuals, petites, groundcovers, perennials, grasses, vines, shrubs, and trees and conifers.

Each Plant Select description includes its scientific name, common name, mature size, flower type, bloom time, and best features. Understandable icons give details on sun and water requirements, as well as if the plant attracts pollinators or if deer resist browsing it.

The “Landscape Use” information is meant for gardeners who have difficulty matching plants to place or are unsure of how to combine plants for the most striking effect. The descriptions make suggestions for perfect placement and the best Plant Select companions.

Many of the gorgeous, full-color images show both a close-up view of the plant and a shot of how it looks in the landscape when in full bloom. One of my favorites is Redleaf rose (Rosa glauca) shown as a fabulous specimen plant, and closeups of the star-like single pink flowers and brilliant red hips.

An especially nice feature for this volume is the Plant Reference Guide in the back of the book. This guide provides a quick resource for matching the right Plant Select plant to the right spot in the landscape.

Besides the typical categories, there are two additional and interesting categories: Special landscape use and North American roots. Not every plant has a special landscape use, but when a plant is recommended for “dry shade, cold hardy,” like Denver Gold columbine (Aquilegia chrysantha), gardeners can trust the endorsement.

Prairie Jewel penstemon (Penstemon grandiflorus) is one Pretty Tough Plant in my xeriscape.

I’ve grown many different Plant Select recommendations in my perennial beds, and I can vouch for their resilience – one of the seven qualities a plant has to have to be added to the program.

In addition to being able to stand up to a challenging climate, Plant Select plants have to thrive in a variety of conditions, be water smart, have that “it” factor, resist insect pests and plant diseases, offer long-lasting beauty, and aren’t invasive.

I can tell Pretty Tough Plants was a labor of love by a group of passionate plant people. The photo credits read like a list of area Who’s Who, from well-known horticulturists to CSU Extension Master Gardeners. Pat Hayward and David Winger had the happy task of sorting and selecting images, including many of their own.

By Jodi Torpey
A Denver Master Gardener
(Timber Press provided a complimentary copy of Pretty Tough Plants for this review.)

Is Your Xeriscape Ready for the Spotlight?

xeriscapeIf you think your water wise garden is ready for its close up, the Denver Botanic Gardens would like to hear from you. The DBG is looking for showcase gardens to feature on its Bonfils Stanton Water Wise Landscape Tour this spring.

Denver metro area gardeners who’ve taken their landscape water conservation efforts to the next level are encouraged to apply to be a tour garden. Selected gardens demonstrate the key principles of a water-wise landscape design.

To be considered, your xeriscape should feature a yard with either less traditional lawn or lawn alternatives, include native flowers and shrubs, have plantings of other drought-tolerant plants, and use water-conserving irrigation systems. It should also be beautiful, too.

The selected landscapes need to be in peak shape on Saturday, June 17, from 10:00 a.m. to 3:00 p.m.

If you have an anxiety attack at the thought of a few hundred people strolling through your backyard, this opportunity might not be for you. But if you’d like to help inspire others with your xeriscaping efforts, you might enjoy chatting with people throughout the day and answering questions about your experience, how the design saves water, how much maintenance is required, and the names of individual plants.

If you’re interested, apply sooner rather than later. “This is a rolling admission process so early submissions may improve the likelihood of selection,” says the DBG. For more information and to receive an application, send an email to Rachael Jaffe (rachael.jaffe@botanicgardens.org) or call 720-865-3613.

Getting Started with Xeriscaping

If your landscape isn’t tour-worthy – or you’ve been thinking about xeriscaping and don’t know where to start – now’s a good time start planning. Start by rethinking the ways you currently use water in your yard.

If that sounds overwhelming, start by transforming a small portion of your landscape. Small xeriscapes will still help conserve water. Look around your landscape and find the places where water use is the highest. Then find ways to reduce or limit irrigation, like seldom-used areas or parts of the yard that are highly maintained.

One of the best ways to save water in the landscape is by cutting back on turfgrass. How much irrigated lawn do you need and how much can be replaced with a lawn alternative? Just because you’ve always had a large lawn doesn’t mean you use it. Low-water grasses, ground covers, perennial flowers, and drought-tolerant shrubs can fill the space.

Another way to save is by rethinking ways to irrigate lawn areas separately from planting areas. Traditional systems can be replaced by low-pressure, low-angle sprinklers. In flower beds, use drip irrigation or soaker hoses under mulch.

Fill your xeriscape with colorful, climate-adapted plants that are known to grow well in our area, like the plants introduced through the Plant Select program. Group plants by their water needs, clustering together those that use less water in drier areas and those that need slightly more water in moister areas.

Mulch is also an important part of a xeriscape because it helps maintain soil moisture and reduce soil temperature. Depending on the plants you select, you may need rock, gravel, bark, wood chips or straw. Some xeric plants do better with inorganic mulches that let fast-falling rains percolate down to plant roots while reducing runoff.

CSU Extension has many excellent (and free) resources for getting started with xeriscaping. This fact sheet on transforming a conventional landscape to a xeriscape may lead to having your yard be part of a water wise garden tour in the future.

By Jodi Torpey
A Denver Master Gardener

It’s Winter and, Yet, I Dream of Cactuses

It’s January.  As I write, it’s cold.  It’s snowing.  The garden is frozen solid.  There isn’t much that can be done out in the garden.  But indoors, we can do a lot of thinking about and planning for about our gardens.  For me, this also includes thinking back to what has already been achieved. My special joy has been planning, making and planting my “desert garden”.

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Prickly pear peeks out of the snow

Having gained my gardening skills and horticultural knowledge in the temperate south of England, I was excited on moving to Colorado to try my hand at growing these interesting, drought tolerant plants.  Cactuses in England are generally small prickly jobs which sulk year-round in dry pots on the windowsill, gathering cobwebs.  I knew virtually nothing about them when I came to live in the USA.  My husband wasn’t much better; he told me he knew his cactuses had been over-watered when he saw mushrooms growing in their pots!

Call it what you will – rock garden, trough garden, crevice garden, desert garden. From big deserts to tiny tufa troughs, cactuses and succulents can be grown and enjoyed in many situations.  I know it’s the middle of winter right now, but I’m thinking of the sunny joy of seeing the Community Heroes Crevice Garden in Arvada and the new steppe gardens at Denver Botanic Gardens in the summer of 2016.  These showed me what could be achieved.  And as I gaze at the tips of Opuntia (prickly pear and cholla) plants poking through the snow in my front yard today, I am in awe at the extremes these amazing plants can tolerate.

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Opuntia x pinkavae

 

 

Our front yard faces north, not auspicious for cactus growing, but safely out of bounds to the dog and small grandchildren, and raised up above the sidewalk, so safely out of reach of passers-by.  The area I designated to be the “desert garden” is about 20 x 10 feet, bisected by the path from the sidewalk to the front door.  Despite its northerly aspect, this area does get a lot of sunshine from spring to fall.  A minimum of six to eight hours of direct sunlight daily is recommended for cactuses.  When we moved in, this part of the garden was just a boring flat patch of clay soil with rather elderly wood mulch strewn over it.  Again, not exactly the well-drained, lean (in terms of nutrients) soil usually associated with cactuses.  But I like a challenge!

To get things started, I raked off the wood mulch and underlying landscape fabric to reveal a flat, compacted, grey soil surface covered in the wriggling, white stems of bindweed like ghostly spaghetti.  I pulled as much of the bindweed as possible. Then to create some height and slopes I dug and shaped the soil into small hills sloping down towards the sidewalk.  We inherited hundreds of large granite boulders with the back yard, so my son and husband hauled a couple of dozen out to the front for me.  I chose the most attractive boulders and made sure they were of similar or complementary colors.  These were placed on the slopes, either singly as “specimen boulders” or in groups forming little “canyons” in which I could plant.

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Rocks, soil, river rock and neighbor’s turf

The slopes help to ensure rain (when we get it) runs off quickly so the plants don’t sit in puddles.  Pockets of water are trapped by the boulders giving little damp areas against the boulders and allowing water to slowly trickle down into the soil below.  To improve the soil drainage further, I dug in a couple of trailers’ worth of “squeegee” to a depth of approx. six to eight inches.  This is the name around here (I gather) for crushed gravel.  It is pinkish in tone and halfway between pea gravel and sand in size. Areas of small river rock (obtained for free from a neighboring garden which was being “re-done” – I love a freebie!) were laid as a transition from the “desert” to the greener area of the yard and the sidewalk.  After planting, a thick layer of pure squeegee was used as a mulch over the whole area.  This has been very effective at keeping the bindweed at bay, helped by merciless hand pulling of any little shoots that do make it to the surface.

The choosing of plants followed considerable book research, web browsing and advice from local nurserymen.  I used a mix of cactuses, succulents, grasses, small drought-tolerant perennials and bulbs.  Naturally, none of these are hot-house types.  They are all cold hardy down to at least Zone 4.  For many of them their natural environment is arid mountain-sides in Arizona and New Mexico where they bake in the summer and freeze in the winter. A couple of dwarf pines provide year-round green and structure.  (I had to remind myself that these two needed regular watering, unlike the rest of the desert garden, as they are young trees, albeit small.)

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Pinus mugo var. pumilio

Planting took place in June 2015, so these plants are now “enjoying” their second winter in our garden.  They spent two and a half months under snow in winter 2015/6 and came up smiling in spring 2016.  There were just two losses, both small Yuccas which had rotted at the crown.  Fortunately, I had extras safely potted up behind the house, so they were immediately replaced.

For the first summer, I watered maybe twice a week, using the mist spray on the hose head.  The second summer, 2016, I did not water at all.  The winter snow that laid on the area for two or three months or more, had provided a good reservoir of moisture which saw the garden right through the summer.

The immediate effect after planting was of a lot of very small plants stranded in a gravelly desert.  I believe in buying small and being patient for a year or two while the plants bulk up, seed around and acclimatise to their environment.

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Just planted, June 2015

 

And, now, after another summer, they are starting to do so.  I see little “pups” on the Echinocereus.  There are Sedum and Stachys seedlings. The stars are the Opuntias (tree chollas and prickly pears) and the Delospermas.  These have grown quickly and the Delospermas were carpets of jewel-like flowers for months on end.  Dianthus and Artemisias are soft foils to their prickly companions. Groups of Nasella tennuissima provide a feathery backdrop and transition to greener and moister plantings at the rear.  The gentle movement of these grasses is a nice contrast to the static cactuses. The little species tulips ‘Persian Pearl’ popped up beautiful purple-red blooms with yellow centers in spring.  I hope to see more of these this coming spring.

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Tulipa pulchella @Persian Pearl’

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Delosperma ‘Fire Spinner’

 

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Summer, 2016 (after the hail storm had knocked off all the flowers!)

 

Now it is getting established, it really doesn’t require a lot work.  No watering if we have enough snow in winter.  Minimal weeding.  A gentle blow-off of leaves and some careful extracting of same from the Opuntias’ prickles with the kitchen tongs once in the fall.  That’s it.

I love my desert garden and see passers-by enjoying it too and that just adds to the pleasure for me.

PS:  Cactus? Cacti? Cactuses?  Who knows … ?? Who cares … !!

Anne Hughes/a Denver County Master Gardener

https://communityheroesgarden.jimdo.com/

http://www.botanicgardens.org/

www.coloradocactus.org

Hardy Succulents: Tough Plants for Every Climate by Gwen Moore Kelaidis. Publisher: Storey Publishing.

Cacti and Succulents for Cold Climates by Leo J Chance. Publisher: Timber Press

Plant List

Cactuses

Echinocereus coccineus

Echinocereus triglochidiatus ‘White Sands’

Escobaria forcottei ‘Koenesii’

Agave utahensis var. kiahabensis

Tree cholla – Opuntia imbricata var. arborescens ‘White Tower’

Tree cholla – Opuntia arborescens var. viridifloa ‘Santa Fe’

Creeping cholla – Opuntia clavata

Prickly pear – Opuntia x pinkavae

Texas red yucca – Hesperaloe parviflora

Yucca flacida ‘Bright Edge’

Herbaceous perennials, bulbs and grass

Dusty miller/artemisia – Artemisia ‘Beth Chatto’ & Artemisia absinthium ‘Silver Frost’

Woolly thyme – Thymus pseudolanuginosus

Yarrow – Achillea sps. various

Sedum- Sedum spectabile various

Pinks- Dianthus sps. various + garden cuttings

Rock rose – Helianthemum sp.

Ice plants – Delosperma ‘Fire Spinner’ &  ?

Two row stonecrop – Sedum spurium ‘Tricolor’

Other stonecrops – ‘Vera Jameson’, ‘Lidakense’, ‘Angelina’

Mullein – Verbascum bombyciferum ‘Polar Summer’

Lambs ears – Stachys byzantinus

Feathergrass – Nassella tenuissima ‘Ponytails’

Species tulip – Tulipa pulchella ‘Persian Pearl’

Trees 

Dwarf mugo pine – Pinus mugo  var. pumilio

Dwarf mugo pine – Pinus mugo ‘Teeny’

Gardening Between the Rocks

little-pickles-plant-othonna-capensis

Little Pickles Plant, Othonna capensis at CHCG

Have you ever marveled at a vigorous plant thriving in the narrow gap between two rocks? Or wrestled with a weed that stubbornly grows through the crack in a sidewalk?  The tenacity of plants to grow, and sometimes prefer, these tight settings is the premise behind crevice gardening, a form of rock gardening which is gaining in popularity.

To learn more about crevice gardens, a group of Denver County Master Gardeners recently toured the Community Heroes Crevice Garden (CHCG) located at the Apex Simms Street Recreation Center in Arvada. CHCG was designed and built by  Kenton Seth and his team in 2014-2015. It is one of the largest crevice gardens in the world, spanning over 1,000 square feet, built with 60 tons of Dakota sandstone from southern Colorado, 14 tons of sand and 20 tons of gravel.

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Pulvinaris ruschia, mat shrubby iceplant in winter at CHCG

Crevice gardens mimic mountain terrain through the use of flat stones which are laid vertically and buried deeply to create narrow gaps. The entire rock structure is “engineered” for stability with the care that a seasoned mason builds a dry stacked retaining wall. The stones keep the plants cool during the hottest part of the day and create various microsystems depending on the garden’s orientation. The gaps are filled with a porous, sandy planting mixture which is layered to promote optimum drainage and deep root development.

Specimens are planted “bareroot”, meaning the original potting medium is removed prior to planting. Roots are then gingerly tucked in the crevices. Once plants are established, CHCG is watered  by overhead irrigation every two weeks or less.  Crevice gardens generally showcase xeric plants, such as delosperma, hens and chicks, species tulips and manzanita, to name a few.  Trees and tall plants which would shade the garden are discouraged. The majority of plants at CHCG are from the dry, cold grasslands of the Steppe regions. A complete list of the plants used  at CHCG and directions for starting a crevice garden can be found here.

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Initial Planting of Community Heroes Crevice Garden

CHCG is a young, ambitious public garden. It’s very much a living laboratory (but then, aren’t all gardens?). It will be interesting to visit it periodically to see its development and seasonal changes. We are fortunate to have several established crevice gardens in Colorado including at the Denver Botanic Gardens (within the Alpine, Mordecai and Steppe gardens) and Vail’s Betty Ford Alpine Gardens (home of the International Alpine Crevice Garden).

If you are interested in trying crevice gardening, Kenton offered that growing plants between a few vertical, closely set rocks in the ground or in a stone trough is an easy and fun way to get started!

Photos courtesy of Kenton Seth

Written by Linda McDonnell, a Denver County Master Gardener.

 

 

 

 

Is a new tree on your wish list?

Not all gardeners enjoy reading seed catalogs.  If you are more interested in planning for a new tree then here are a few resources to get you started.

Five Favorite Bulletproof Plants for Denver Gardening

Just about every gardener I know lost a favorite plant or two over the winter. Most of my hardy roses died to the ground, but eventually returned.  Sadly, the tall and lovely redleaf rose (Rosa rubifolia) is gone for good. Whether a rose, shrub or fruit tree, losing a prized plant is like losing an old garden pal.

The only way to get over the loss is to replant with something that will survive the challenges of living in our climate. Here are five bulletproof plants that seem to thrive in spite of the vagaries of weather:

Kintzley's Ghost honeysuckle smallKintzley’s Ghost honeysuckle (Lonicera reticulata ‘Kintzley’s Ghost’)

If you’re looking for a dependable woody plant, Kintzley’s Ghost honeysuckle is it. I planted this Plant Select recommendation years ago and it continues to surprise me every year. The vine does well with only the precipitation it receives. When there’s wet weather through the winter and spring, it grows a bit taller with more foliage. During drier years it still shows up and looks good. In addition to its low-water, low-maintenance needs, I appreciate the eucalyptus-like foliage on vines that crawl up and over the picket fence.

Gold flame spirea smallGoldflame spirea (Spirea x bumalda ‘Goldflame’)

In 2001 I planted three of these tidy shrubs and they’re still going strong. Even after the shock of the sudden freeze last November, all three returned with only a few dead branches. A quick trim was all they needed. This spirea is a compact deciduous shrub that grows to about 3 feet tall and just as wide. Drought-tolerant once established, it can brighten any spot with crimson-red leaves in spring that turn to vibrant green by summer. Reddish-bronze fall color is an added bonus. Small pink flowers can bloom twice over the season if dead-headed.

Silver Fountain butterfly bush smallSilver Fountain butterfly bush (Buddleia alternifolia)

This Plant Select winner is a beautiful shrub with graceful arching branches. In spring there are tons of light-purple flower clusters that attract butterflies like crazy. If you plant one, be sure to give it plenty of room because it can grow to more than 10 feet tall and wide. I’ve found the only downside is the long branches are surprisingly brittle during winter and some may break under heavy loads of snow — nature’s way of pruning so you don’t have to. This butterfly bush prefers well-drained soil and is adaptable to low-water conditions.

yarrow smallMoonshine yarrow (Achillea ‘Moonshine’)

Some gardeners think yarrow is the least sophisticated of the xeric plants, but I appreciate it because it loves my landscape. Its tall, shrub-like habit makes a nice backdrop in a xeriscape garden and the silvery-gray foliage and bright yellow flowers really shine in summer. I started with two plants but yarrow needs to be divided every few years, so I’ve transplanted more around the yard. I leave some flowers on the plant through winter, but I also clip some to use in dry table arrangements and crafts projects.

Brown-eyed Susans smallBrown-Eyed Susan (Rudbeckia triloba)

Brown-eyed Susan is smaller than its black-eyed cousin, and that’s fine with me. This biennial coneflower behaves more like a perennial because of its generous seed-sowing nature. My large collection started as two small starts and have spread throughout the garden on their own. The sunny yellow, daisy-like flowers have beautiful brown “eyes” and stand tall from mid-summer through fall. Bees and butterflies are attracted to the long-lasting blooms, but they make nice cutting flowers, too.

By Jodi Torpey
Denver Master Gardener