If the foliar spines (teeth on the margins of the leaves) of English holly are too nasty, holly olive, Osmanthus heterophyllus, might be a more docile option. It lacks the occasional bright red berries and the very glossy finish on the leaves, but is much easier to handle than real holly is, since the spines are not nearly as sharp. If you look closely, you can see that the one to two and a half inch long leaves have opposite arrangement (are in opposing pairs along the stems) instead of alternate arrangement (are single along the stems) like those of holly.
The more popular varieties of holly olive have some sort of variegation of white or gold. Variegation can be spots, blotches or more refined margins. Most of the modern variegated varieties prefer to stay less than six feet tall. The old fashioned unvariegated holly olive can get more than twenty feet tall when very old, but the upper foliage lacks the distinctive foliar spines of lower foliage. The tiny and mostly unnoticed flowers are pleasantly fragrant.
Remember when gardening took advantage of the great climate and soil of the Santa Clara Valley? Single story suburban homes with low suburban fences had generous sunny garden space. Now, multiple-storied homes on smaller parcels surrounded by big fences leave only minimal space for shady gardening. Rhododendrons, azaleas, hydrangeas and all sorts of ferns are more popular than the many fruit trees that were so much more common only a few decades ago.
‘Washington’, ‘Robertson’, ‘Valencia’ and ‘Sanguinelli’ oranges that have quite a history in local home gardens are now not much more common than the previously rare Mexican orange, Choisya ternata, which, although related, provides only mildly fragrant flowers without edible fruit. The modest white flowers are only about an inch to an inch and a half wide on loosely arranged trusses, but show up nicely against the rich glossy green foliage. They can bloom anytime, and happen to be blooming now because of the pleasant weather. Otherwise, they prefer to wait until late spring and early summer.
The trifoliate leaves (which are palmately compound with three smaller leaflets in a palmate arrangement) are about two or three inches long and wide. The individual leaflets are about one and a half to three inches long and nearly an inch wide. Foliage can get sparse on big old plants, as they eventually reach lower floor eaves. Occasional pruning of lanky stems can improve foliar density and keep plants as low as three feet. Mexican orange does not actually resemble real orange trees much, but provides nice glossy foliage that is occasionally enhanced by simple softly fragrant flowers.
Floral fragrance is likely the primary asset of sweet box, Sarcococca ruscifolia. However, the splendidly glossy and evergreen foliage is as appealing as that of any of the various boxwoods. It is darker and richer green, with orderly arrangement on nimble and arching stems. Individual leaves are small but larger than boxwood leaves, and with pointier tips.
Sweet box blooms during winter, with deliciously fragrant but tiny pale white flowers that are not much to see. They are unlikely to get credit for their impressive fragrance without close investigation for its source. Vigorous plants may produce a few rich maroon berries that contrast delightfully with the rich green foliage. Cut stems work well with cut flowers.
Because it is naturally an understory species, sweet box not only tolerates partial shade, but actually prefers it. Harsh exposure fades its foliage. The dense foliage on wiry stems adapts to low hedging. It is better with alternating cane pruning to remove old stems and promote fresh basal growth. Overgrown specimens respond quite favorably to coppicing. They grow to three feet high.
It may not seem like much to take notice of. Sweet olive, Osmanthus fragrans, resembles glossy privet, but is neither as glossy nor quite as richly green. The dense and evergreen foliage can work about as well for a formal hedge though. It is even better as a small and billowy tree. It gets at least as high as ground floor eaves, and can reach upstairs eaves.
The primary allure of sweet olive is its delightfully pervasive and fruity floral fragrance. Its small and slender clusters of tiny pale white, yellow or gold flowers are mostly obscured by foliage. For those who are unfamiliar with it, the fragrance might be difficult to identify. Bloom is most abundant before and after summer. Sporadic bloom happens at any time.
Because sweet olive is more olfactorily appealing than visually appealing, it works quite nicely as in informal hedge behind prettier plants. It can stay narrow between windows of neighboring homes that are a bit too close together. If enough flowers are available, they might flavor tea and confectionery. A cultivar with variegated foliage is unfortunately rare.
More than a dozen species of Phlox are native to various ecosystems of California. They are generally uncommon within refined home gardens though. The more popular garden phlox, Phlox paniculata, is native east of Kansas. It naturalizes in some regions, such as the Pacific Northwest. Locally, it might self-sow only where it gets water through summer.
Garden phlox can get as high and wide as three feet. Some modern cultivars should stay a bit more compact. Individual flowers are only about an inch wide, but bloom with many others on dense panicles that are as wide as six inches. This richly fragrant bloom is red, pink, white, pastel orange or pastel purple, and continues for almost a month of summer.
As its potential for naturalization suggests, garden phlox is not particularly demanding. It appreciates good exposure, but can tolerate a bit of partial shade. It enjoys richly organic soil but can survive within soil of mediocre quality if it is not too dense. Regular watering sustains bloom, but established plants can survive with minimal watering after blooming. Propagation by division of large or overgrown plants while dormant through late winter is very easy.
In eastern North America where it grows wild as a native, garden phlox, Phlox paniculata, is modest but classic perennial that gets more than four feet tall with pinkish lavender flowers from late summer through early autumn. Modern garden varieties are mostly somewhat more compact with pink, red, light purple or white flowers. Many have fragrant flowers; and some have flowers with lighter or darker centers. Butterflies and hummingbirds dig them all.
Locally, garden phlox probably looks best with slight shade or among other lush plants, only because humidity is so minimal. Otherwise, it would be just as happy out in the open. In well watered gardens with rich soil, it sometimes self sows a bit, but rarely naturalizes continually enough to revert to a more natural (wild) state like it can in gardens on the west coast of Oregon and Washington. Garden phlox can be propagated by division of mature plants either after bloom in autumn or in spring.
The warm nights between the dog days of summer are ideal for night blooming jasmine, Cestrum nocturnum. That is when it disperses its famously sweet fragrance to attract bat and moth pollinators. A bit of humidity, although unnecessary and locally rare, enhances the permeating nature of the fragrance. Some might find such fragrance to be excessive.
Otherwise, night blooming jasmine is quite modest. Those who experience the powerful fragrance at night may be unable to identify its source while visible during the day. Small floral trusses hold several small and narrowly tubular flowers that are about an inch long. Bloom is greenish white or pallid yellow. Simple evergreen leaves are a few inches long.
Therefore, night blooming jasmine works best in the background of more colorful bloom. It will not mind if other flowers get the credit for its fragrance. With regular watering, night blooming jasmine is happy in unseen areas between buildings, and under high windows that lack views. Aggressive pruning only in early spring promotes blooming new growth. Most plants stay shorter than ten feet. Rare white berries are toxic.
As winter turns to spring, pink jasmine, Jasminum polyanthum, blooms with abundant, loose trusses of small but very fragrant star shaped flowers. The flower buds that are initially deep pink open to soft pink, and then fade almost to white. Light shade inhibits bloom and limits foliar density, but does not prevent the wiry vines from climbing to twenty feet or so. The dark green leaves are compound with five or seven leaflets. Pink jasmine is one of the few vines that can climb lattice and light trellises without tearing them apart like wisteria and so many other popular vines eventually do. Even if it escapes confinement and gets into trees or onto roofs, it does not get too far to be pruned back within bounds.
Attracting pollinators is serious business for flowers that do not rely exclusively on wind for dispersion of their pollen. Many flowers attract pollinators with flashy color. Some reward their pollinators with sweet nectar. Many prefer to use fragrance. Most flowers use a combination of two or more of these tactics.
Fragrances are designed by the flowers that use them to appeal to the discriminating taste of specific pollinators. Most are sweet. Some are more perfumed. A few are even quite objectionable to people because they are tailored to flies. Fortunately, flowers with foul fragrances are rare in gardening.
The most fragrant flowers are often less abundant than flowers that rely on wind for dispersion of their pollen, or less colorful than flowers that rely on visual appeal to attract pollinators. Yet, the fragrant flowers of wisteria vines and lilacs are both profuse and colorful. The surprisingly big and fragrant flowers of ‘Charles Grimaldi’ angel’s trumpet are bright yellow.
Mock orange (Philadelphus spp.) conforms to the stereotype of fragrant flowers a little bit better, with somewhat small white flowers that are incredibly fragrant. The small pale pink flowers of daphne are even less impressive and nearly hidden among their foliage, even though their fragrance can not be ignored. The sweetly fragrant flowers of Japanese honeysuckle vines are abundant but not too colorful. Star jasmine vines likewise bloom fragrantly and abundantly, and their bright white flowers contrast better against their glossy green foliage.
Night blooming jasmine is not appealing enough for prominent placement, and is not even fragrant during the day, but will be unbelievably fragrant on warm summer nights. Just as fragrances appeal to specific pollinators, nocturnally fragrant flowers specifically appeal to insects or bats who are active at night.
Freesia, hyacinth, lily,narcissus and some types of iris are very fragrant as well as colorful now that they are blooming for early spring. It is unfortunate that their flowers do not last long, and that there are not any comparable flowers later in the year. The same annual sweet peas and stock that bloom about now can be planted again later for autumn bloom. Sweet peas are easiest to grow from seed. Stock is easiest to grow from cell packs, and since it is actually perennial, sheltered plants can survives through warm summer weather to bloom again in autumn. Annual sweet alyssum can bloom anytime while the weather is warm.
It is presumptuous to believe that all the fancy breeding that is done to enhance the characteristics of flowers necessarily ‘improves’ them. Breeding only makes flowers more appealing to those who enjoy them in their gardens. Most flowers were already quite efficient for their intended function in their respective natural habitats long before humans started tampering with them. As far as flowers are concerned, they only need to get pollinated.
Some flowers use flashy color or patterns to be visually attractive to pollinators. Others use fragrance to be olfactorily appealing. Small but profuse flowers that are neither colorful nor fragrant have given up on insect or animal pollinators, so instead rely on the wind to disperse their pollen.
Not many flowers are both remarkably colorful and remarkably fragrant like freesia, lilac and wisteria were earlier in spring. Lily and bearded iris are of course very colorful, but not all types are fragrant. The big and bold flowers of cereus cactus, moon flower and angel’s trumpet are only fragrant because they bloom at night, and rely on nocturnal pollinators who benefit from a bit more guidance in the dark.
Many fragrant flowers are somewhat showy, like gardenia, star jasmine, pink jasmine and honeysuckle. (However, gardenia are almost never healthy and showy locally.) Many of the most reliably fragrant flowers are really not much to brag about. Pittosporum tobira, Pittosporum undulatum and sweet osmanthus are known more for the appealing evergreen foliage than for their small and nondescript flowers. The flowers of sweet osmanthus may actually be difficult to find amongst the obscuring foliage. Night blooming jasmine is sometimes planted around corners or in the background because even the foliage is not too appealing, although the powerful candy-like fragrance is a favorite for warm evenings.
Fragrant flowers can be annuals like sweet alyssum, bulbs like hyacinth, or perennials like tuberose. Woody plants with fragrant flowers can be vines like stephanotis, shrubs like mock orange (Philadelphus spp.), or trees like Southern magnolia. Some have brief bloom seasons, while others bloom for quite a while.