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”.
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.
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.
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.)
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.
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.
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
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
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’
Dwarf mugo pine – Pinus mugo var. pumilio
Dwarf mugo pine – Pinus mugo ‘Teeny’