Some years ago, we began planting a hot, dry slope with a southern exposure and poor sandy soil.
At that time, we canvassed the nurseries looking for plants that would do well in full sun, withstand hot, dry winds, and be supplied naturally with just enough water to keep them alive during the summer.
Books and growers gave us advice, and we made long lists, but they had not the remotest idea of what we meant by hot, arid, and windy.
True enough, we purchased and planted many things like full sun and sandy soil, but in July and August, they were all blasted, and so were our hopes.
All, except one small valiant plant that continued to look “green and healthy despite the heat.
This was a young plant of the helianthemum variety Apricot. We immediately started scouting around for more of this hardy subshrub.
Rock Roses and Sun Roses
Helianthemums, also known as rock roses and sun roses, are native to North America, South America, Europe, North Africa, and Western Asia.
The vast numbers of species are interesting but not as desirable as the hybrids, which have been produced in better colors, larger flowers, and hardier strains.
Most nurseries today list only the hybrids with the possible exception of H. ALPESTRE, H. APPENNINUM, and H. A. RHODANTHUM, no doubt the best of the species for the garden.
Most of the hybrids are offspring of H. NUMMULARIUM (VULGARE). Our original planting of Apricot is still with us after 9 years.
Foliage
Each spring, it produces masses of lovely apricot-colored flowers, and again, in later summer and fall, it treats us to a mild burst of bloom.
The foliage of Apricots is exceptionally good, the leaves being broader than those of most other sun roses and a good, dark, glossy green in color.
Nearly all colors are in double forms, but I prefer the single types. I could be mistaken, but I believe the single-flowered plants bear more profusely.
Among the various varieties we have grown and liked is Goldilocks, with soft gray foliage and large, clear yellow flowers.
Habit of Growth
Its growth habit is rather loose and airy, but with judicious pruning, the plants may be kept neat and compact.
American Beauty is a lovely colored importation from Europe; the plant is a bit rangy, but the flowers are large, lovely, and vividly colored, and here again, the plant may be shaped by pruning.
‘St. Marys is a good white, and Ben Nevis we consider our most distinctive. Ben Nevis is very low growing, almost a creeper, with fine flowers of chrome yellow having a central ring of burnt orange, generously giving a second blooming in autumn.
A recent introduction is Mrs. Mold with rose-colored, fringed petals. The plant is very compact and bids well for a tidy border plant.
Pest-Free
We have three newcomers: Seattle, Dazzled, and Flame. Only Flame has bloomed, and it was everything the catalog promised.
The flowers are very large, of good substance, and brilliant pink in color with a deeper central ring.
Among the older pink shades, Wendels Rose, probably one of the oldest hybrids, has lovely pink flowers and silver-gray foliage. Other good pink colors are Pink Beauty, Rose Queen, and Rose Glory.
In growing helianthemums, we have found only one pest—a mealybug—that attacks the stem just at ground level. Otherwise, they are completely pest-free.
Mulching with Peat Moss
Even our greedy snails seem to shun them for more tender morsels. We combat the mealy bug by watering with a solution of nicotine sulfate made up in a watering can and applied freely to the base of the plant.
When the summer is very long, hot, and dry, we give the plants a mulch of peat moss and a good deep watering once a week.
This mulching with peat moss keeps the foliage fresher and more luxuriant. Light mulching protects the plant and foliage during the winter in very cold climates. This is unnecessary here, where it never gets colder than 18° degrees Fahrenheit.
Propagation by Cuttings
After blooming, the long straggling stems must be pruned back to keep the plant compact and trimmed.
Some varieties may be pruned more severely than others, depending on the plant’s growth habit.
Severe pruning would not be necessary or desirable on a plant that naturally grows compactly.
For hybrid sun roses, propagation by cuttings is the most satisfactory means of increasing stock.
Spring Cuttings
We have found that cuttings taken in spring (February and March in California) or July and August are the most reliable.
We have succeeded with cuttings taken through fall and early winter, but the rooting percentage is lower.
3-inch softwood cuttings placed in sand under glass will root well in 5 or 6 weeks under good conditions.
After forming sizable bundles of roots, they are potted into 3- or 4-inch pots in well-drained, friable soil.
Growing Like One Long Willowy Stem
After potting, most helianthemums tend to grow one long willowy stem, which, if allowed to continue growing, will produce a leggy, unsightly plant.
So, to ensure a well-formed plant, it is necessary to snip this rampant grower back to encourage breaking or branching lower down.
Helianthemums from seed are easy and interesting. Some nine or ten years ago, we grew several fine plants with a great variety of gray, green, and silver in the foliage.
These seeds came from England. Northwest Plantsmen will soon offer more new varieties.
44659 by Virginia R. Stewart