Hypericums or St. John’s Worts are among the most gratifying plants for the summer effect—valuable both for their quantities of yellow flowers produced over a long period and for their adaptability to various growing conditions.
They are singularly untroubled by plant diseases and insect pests and thrive in nearly any situation offering a porous open soil and a generous amount of sunlight.
In all, there are about 200 species of Hypericum, both herbaceous and shrubby plants. A number grow as shrubs in areas of the mild climate, but in colder regions start new growth from woody crowns at ground level each spring.
Hypericum Characteristics
Leaves showing great numbers of minute translucent dots when observed against the light are borne in pairs or some species in whorls along the stems. These leaf characteristics are very convenient aids in identification.
The yellow flowers are an even easier means of immediate recognition, as cultivated kinds are characterized by a showy mass of stamens filling the central part of each bloom.
The five petals are a rich background for the boss of stamens, and underneath these, five green sepals strengthen the flower structure.
Except in a single species, the Tutsan of southern Europe and Asia Minor, which has berry-like fruits, the slender pistil of each flower matures into a woody capsule containing many fine round seeds.
Hypericum Patulum
Golden Cup St. John’s Wort, Hypericum patulum (Hypericum with spreading branches), may represent a group of Asiatic species that have made important contributions to gardens.
The typical form of Hypericum patulum was described from plants studied in Japan by Carl Peter Thunberg, the Swedish physician so closely connected with many decorative plants from Japan.
A height of 3′ to 4′ feet is usual in this type, and during most of the summer, the tips of the branches carry cymes of 2-inch flowers of the pattern outlined above.
This Japanese plant is considered tender when winter temperatures remain around zero for a considerable time.
In hardiness and also in showy flowers, this type is surpassed by variations from the mainland of Asia.
Dr. Henry’s Herbarium Noteworthy Plants
During his vigorous years with the Chinese Maritime Customs, Dr. Augustine Henry—an ardent plant collector from 1881 to 1900—sent amazing quantities of herbarium specimens and seeds of some very noteworthy plants to England.
Among the seeds were some of the stronger and more hardy varieties of this Hypericum, which is named for him (Hypericum patulum henry) and is the variation of the species most generally offered by nurseries in this country.
It is extremely close to a form collected years later by the great Scottish plant hunter George Forrest.
Forrest Hypericum
However, Forrest Hypericum (forma foresti) has a little larger flower borne in even greater abundance.
Technically, these two variations may be recognized by their acutely pointed sepals; the Japanese type has blunt or roundish sepals.
Other variations have somewhat less conspicuous blooms and are of limited interest as garden subjects.
The species ranges from south-central Asia to Japan, with the group’s center occurring in the Himalayas.
It was merely a quirk of history that the farthest outriders, the Japanese representatives, were noted first by systematic botanists. So the name given to these has priority and stands for the entire species.
The matter of interest here is that these St. John’s Worts exhibit much variation as wild plants, and when raised from seeds, this same performance occurs in gardens.
Hypericum Sungold
A seedling selected for its outstanding traits by the late M. H. Horvath of Mentor, Ohio, is known today as Hypericum Sungold.
It was derived from the larger-flowered form of H. patulum, first grown in the early 1920s from seeds introduced by George Forrest.
Sungold makes a vigorous, rounded bush, usually about 3’ feet high and about that wide. Its decorative qualities are of the first rank.
Hypericum Hidcote
Also possessing great attractions is Hypericum Hidcote which originated at the famous Cotswold Garden, Hidcote Manor—the first garden property assigned to the National Trust in Great Britain.
The plant appeared as a seedling several years ago. Its twiggy compact growth and a rufflike collar of stamens at the center of the flowers give it great distinction.
A leading horticulturist who has evaluated new plants extensively considers it one of the best shrub novelties to be introduced to our gardens.
Its habit of growth makes Hidcote especially pleasing as a low informal hedge, particularly when it is desirable to have a dwarf barrier that can be cut to the ground every year or two.
Hypericum Moserianum
A survey of this group of St. John’s Worts would be incomplete without mention of Hypericum moserianum, a hybrid between H. calycinum and H. patulum raised at the Moser nursery near Versailles about 1887.
Though this plant has flowers as fine or finer than all its relatives, its growth is more herbaceous and less robust than the others noted here.
Though valuable in mild winters, it is apt to kill back seriously or completely when temperatures fall below 10° degrees Fahrenheit.
It is often suggested that St. John’s Worts may be used to best advantage at the front of shrub borders or associated with groupings of larger shrubs.
These combinations work out acceptably until crowding impairs their growth and reduces the mass of bloom.
In many cases, they are best used with herbaceous perennials or even in place of them.
Hypericum Companion Planting
In the sketch on page 43, Hypericums are used with Lilies and a few other herbaceous plants that contribute to summer bloom in yellow and orange tones.
The grouping makes a border about 6 feet wide along one edge of a home property. Cedar fencing provides background, enclosure, and support for some of the large-flowering Clematis.
An old apple tree is a friendly feature at the end of the border, with its twisted trunk surrounded by a circular wooden bench.
Continuing the cedar fence around this corner furnishes just enough enclosure to make this a pleasant spot for resting during summer.
A few Mountain-laurels (Kalmia latifolia) at the corners ensure accents of green in the winter. If the shade of the apple tree reaches over the corner of the border, this portion could be given over to clumps of Fragrant Plantain – lilies (Hosta plantaginea).
Lilac Chaste-tree
Two plants of Lilac Chaste-tree (Vitex agnus-castus, featured in Article 17 of this series, in Popular Gardening of August 1952) are also included for their delicate summer bloom.
The rectangle under the apple tree has a floor of old bricks laid in sand, and to lessen maintenance, it is very desirable to continue bricks as an edging along the front of the border. Here they should be laid on the edge and sunk to the level of the grass.
The named selections of St. John’s Worts are propagated vegetatively, and it should be noted that Sungold is a patented plant.
The fine hard seeds of the botanical variations and types germinate readily. Seedlings may run up to a foot or more in height and produce some flowers the first summer.
Good Floral Display
Several stems arise from the base in the second year, producing a good floral display, and a tough woody crown is soon developed at the ground level, with a proportionate increase in the size of the clumps and masses of flowers produced.
The floriferous ness of Hypericums is phenomenal. It is doubtful if many hardy plants produce flowers of such size in similar quantities.
With the bloom extending over the entire summer, in most cases, and even well into the autumn with some selections, the value of these plants as garden favorites seems secure.
44659 by Ben Blackburn