Santa Barbara Daisy

Some of us know Santa Barbara daisy by the less appealing name of ‘fleabane’.

Santa Barbara was not exactly its first choice. Santa Barbara daisy, Erigeron karvinskianus, is not even native to California. It is actually from Central America. It just happens to do very well here, and can naturalize if conditions are right. It can be rather grungy through summer in the wild, but with a bit of watering, it can bloom nicely all year.

The thin stems can spread a few feet without getting more than a foot deep. If even shallower growth is preferred, older plants can be cut down or pulled up as they get replaced by their own offspring. The narrow leaves are quite tiny. The white or slightly pinkish flowers are not much bigger, less than half an inch wide, with prominent yellow centers.

Santa Barbara daisy is also known as Mexican fleabane, both because it is actually native to Mexico, and also because it is supposedly useful for repelling fleas. The problem with using it to repel fleas is that only its smoke is effective. There are probably other herbal alternatives that work just as well without being a fire hazard.

Butterfly Bush

Garden varieties are less likely to naturalize than the straight species is.

Many plants are so easy to grow that they become invasive weeds. Butterfly bush, Buddleja davidii, has done exactly that in some regions, and is only controlled here by the arid climate. Yet, once established, it does not need much water at all, and can survive on rainfall in some spots. They only want good sun exposure.

Mature plants can get more than 15-feet tall and half as broad, with long arching limbs. Most garden varieties stay smaller, and some do not get much more than six feet tall. The evergreen foliage is sage green, grayish green or chartreuse. The paired leaves are about the size and shape of willow or eucalyptus leaves.

Conical trusses of densely packed tiny flowers that bloom in mid-summer can be various shades of blue, purple, red and pink, as well as dusty white. Some new varieties bloom soft orange or yellowish orange. The more compact and colorful modern varieties are not as fragrant as old classics are.

Summer Is Not For Planting

New plants are less reliant on irrigation if installed at the beginning of the rainy season.

Autumn is the time for planting. Cooling weather slows plants down so that they do not mind disruption so much. Increasing rain (hopefully) keeps the soil evenly moist while roots slowly disperse. The combination of cooling weather, increasing rain and shorter days keeps plants well hydrated so they can slowly ease into spring.

Why is this important now? Well, it probably is not important. It merely demonstrates why this is not the best time for planting. Only a few warm season annuals and vegetables get planted this time of year. Seeds for certain autumn vegetables get sown now. Otherwise, more substantial plants should wait until autumn if possible.

Mid summer in some ways is the opposite of autumn. While the weather is warm, plants are too active to be bothered. Even minor disruption can be stressful. Soil moisture provided by irrigation is often too irregular and unreliable for dispersion of many new roots. There is less time to recover from stress during shorter nights.

Smaller plants and seeds survive summer planting better than larger plants do. Seeds need to disperse all new roots anyway, so they  will adapt to what they get. They certainly need regular watering, but are quite talented at putting their roots wherever the moisture goes. With a bit more time, smaller plants will do the same.

Larger plants have more difficulty with the planting process because they need to disperse so many more roots to get established. When they get planted, all their roots are initially confined to the volume of media (potting soil) that they were grown in. They are susceptible to whatever happens within  that limited volume.
For example, a small plant in a four inch wide pot is initially confined to less than sixty-four cubic inches of soil. It can double its soil volume to one hundred forty-four cubic inches by merely dispersing roots less than one inch laterally. A tree in a 24-inch wide box needs to disperse roots ten inches laterally to do the same!
It would seem that drought tolerant plants would be less susceptible to the stress of planting in summer.

However, they are more sensitive because they are so reliant on extensive root dispersion. Until they disperse their roots, they actually need to be watered as frequently as other plants do.

Agave filifera

Foliage is better than bloom, and lasts longer.

For a tough perennial that is is grown for striking foliage, the small Agave filifera has a remarkably striking bloom as well. The one and a half inch long flowers are impressive pale green, and mixed with faded flowers. What makes them so compelling is that they are displayed on sculptural floral spikes that stand nearly six feet tall.

Unfortunately, each dense rosette of foliage is monocarpic, which means that it dies after bloom. Pups (sideshoots) sometimes develop as a main rosette deteriorates. If multiple pups develop and get crowded, they can be divided. Each rosette takes a few years to bloom, so should be around for quite a while.

The stiff evergreen leaves get about a foot or a foot and a half long, with unpleasantly sharp tips. Vigorous plants have white filaments that peel from the edges of the leaves. Like all agaves, Agave filifera, does not need much water once established. Unlike other agaves, it can tolerate a slight bit of shade.


Rockrose is just beginning to bloom.

The first bloom is the best. At least it is purported to be. Many of us who are familiar with any cultivar of rockrose, Cistus, might disagree. Bloom begins in spring and continues through summer. The most profuse bloom can be anytime within that range. Some cultivars bloom sporadically but continually. Others bloom in more distinct phases. Cultivars that start later can bloom into autumn.

Bloom is white, pale pink, rich pink or purplish pink. Individual flowers have five petals and fuzzy centers. Flowers of some of the older cultivars have a prominent rusty red spot at the base of each petal. Smaller flowers are more profuse than larger flowers. The small evergreen leaves of most rockrose are somewhat grayish, with a matte finish. Foliage is aromatic when disturbed or warm.

Most rockrose are appreciated for their low and mounding form. If arranged in a row, they can grow into an artificial berm. Most get at least three times broader than tall. Few get taller than three feet. They all appreciate warm exposure. Once established they do not need much watering. Unfortunately, most rockrose do not live much longer than five years. Few survive more than ten years.

silver dollar gum


There are actually a few different eucalypti known as silver dollar gum. The most familiar and largest is Eucalyptus polyanthemos. Mature trees that were popularly planted through the 1960s are about forty or fifty feet tall. Some stay smaller. A few that compete with taller trees are more than sixty feet tall. Trunks and limbs are somewhat sculptural, with fibrous bark.

Grayish foliage on limber stems forms a billowy and rounded canopy that blows softly in the breeze. Juvenile leaves are nearly circular, and more silvery gray than adult foliage is, like silver dollars. Ovate adult leaves are about three inches long and half as wide. Tiny flowers with prominent white stamens bloom amongst the adult foliage in spring and summer.

Smaller trees are often pruned aggressively or pollarded so that they continually produce the more desirable juvenile foliage without bloom. The problem with this technique is that it must be repeated every few years or even annually. Otherwise, vigorous secondary growth can get too heavy and break away.

Eucalypti Are Innately Drought Tolerant

Distinctive foliage provided by red ironbark.

Drought is nothing new here. There could be plenty of rain next winter and for years afterward; but eventually, there will be another series of dry winters, prompting rationing all over again. Landscapers and big box garden centers continue with business as usual. It is up to us to manage our gardens responsibly. Besides native plants, aloes, yuccas, junipers and eucalypti are four groups of formerly popular, drought tolerant plants that are worthy of more attention again.

Eucalypti had gotten a bad reputation even before they became popular the last time around. Tasmanian blue gum, Eucalyptus globulus, that was planted so extensively for wood pulp and timber throughout California, is a huge and extremely messy tree. Yet, it is still the most familiar of the eucalypti.

Garden varieties of eucalypti are much more docile. Even though they drop their evergreen foliage and hard seed capsules throughout the year, they do so on a smaller scale. The tall and elegant lemon gum constantly sheds strips of bark like the Tasmanian blue gum does, but does not get big enough to be too overwhelming.

Because they are so undemanding, and some are somewhat messy, eucalypti are best in unrefined parts of the landscape, and away from lawn. Their mess is no problem over ivy or iceplant. They are happiest where other trees might be unhappy. Generous watering actually inhibits root dispersion, and can cause vigorous but structurally deficient stem growth.

Eucalypti innately prefer to be planted while very young, even from four inch or one gallon (#1) pots. Larger (and more expensive) trees, such as boxed trees, take so long to get established that they get passed up by faster growing tiny (and less expensive) trees. Because they are sensitive to confinement, eucalypti are unfortunately rare in nurseries.

The online catalog of Annie’s Annuals and Perennials, which is famous for excellently weird and undemanding plants, features lemon flowered mallee, red capped gum, silver princess gum, bell fruited mallee and fuchsia gum, all in four inch pots. The bell fruited mallee and fuchsia gum are like large but airy shrubbery that do not get much taller than the eaves.

California Is A Big Place

There are all kinds of natives.

California is a big place, with more environmental diversity than any other state and most other countries. It includes rainy and cool forests of Del Norte County, and dry and hot deserts of Imperial County. The snowy mountains of Placer County and the mild coastal plains of Los Angeles County are here too. There are hundreds of miles of sandy beaches and big fertile valleys.

Consequently, plants that are native to California are just as diverse. Many that are very well adapted to the environments that they naturally live in are not so well adapted to other environments that may be only a few miles away. They really do not want to go to some of the more divergent climates in other regions.

Coastal redwood that is so happy within its natural range on the foggy western slopes of the coast ranges to the north are not so happy on the drier eastern slopes of the same ranges. It probably would not survive for long in the Mojave Desert. California fan palm from the hot and arid region of Palm Springs languishes on the damp and cool western edge of San Francisco.

Most of the popular California native plants are popular because they do not need much water, if they need any at all. However, some are as unhappy with local climate conditions as exotic plants from other continents are. For example, few plants tolerate drought as well as Joshua tree does. Yet, Joshua tree is likely to grow fast and then rot because winters are too damp for them locally.

Of all the excellent plants that are native to California, the most excellent for local gardens are either the few plants that are native to the local region, or the many others that are native to similar regions. They do not need cold Sierra Nevada Winters, hot Death Valley summers, Mojave Desert aridity or San Francisco fog. They are right at home here.

Even natives need some help adapting to a new garden. Confining their roots to cans while they grow in nurseries is very unnatural for them. Once planted, they will need to be watered while their roots disperse enough to survive on rainfall, or with minimal watering.

Barrel Cactus

Barrel cactus spines are serious business!

‘Echino’ translates to ‘spiny’; so the genus name of barrel cactus, Echinocactus grusonii, means ‘spiny cactus’. Duh! The nearly spherical and furrowed (ribbed) plants are completely covered with stout and dangerously sharp spines. The most popular variety, known as golden barrel cactus, has pale amber yellow spines. Another variety has white spines. Tan or ruddy spines are rare.

Growth is quite slow. It takes many years for plants to get to three feet tall. Only plants that are quite mature bloom in spring or early summer with bright yellow or orange flowers that develop in a circle, like a halo around the top of the plant. Pink or red flowers are rare. Old plants typically develop a few pups (side-shoots), which may likewise take many years to bloom.

Like most cacti, barrel cactus wants a warm and very sunny location, and very well drained soil. If they do not get watered too much, they can stay potted for many years. However, because they are so nasty, they are not too welcome on porches or patios where most potted plants live. Because they are so heavy and difficult to handle, they are not as portable as they should be.

Cacti Have Bite Without Bark

Cacti exhibit unique and striking form.

The most inhospitable spots in the garden that no one wants to put any work into seem to be the domain of cacti, whether or not any cacti actually live there. “Oh, I will just put some cactus there!” is cliché in regard to shadeless and dry spots that get too hot with glare from a south-facing wall. Yet, such spots typically continue to be neglected, and the cactus never get planted.

Why are such distinctive and interesting plants considered to be so lowly that they should be banished to the badlands? Why should they be expected to endure what not other plants are expected to endure? After all, there are so many other distinctive xeric plants, like yuccas, agaves and some aloes, that are just as resilient, and according to some, just as lowly.

Cacti really are not as independent as commonly believed. New plants should actually get watered occasionally until they disperse their roots. If they get watered regularly, they need coarse soil that drains very well. Cactus plants that were grown in sheltered spots really can get scaled if planted where they are too harshly exposed during hot weather.

The main problem with cactus is their nasty spines. Simply planting small plants without getting poked is a challenge. Moving big potted specimens or removing overgrown cactus plants without getting seriously perforated can be daunting. So, even though they might do well in the harsh exposure at the curb, they do not belong in such a high traffic area.

Without foliage or conventional stems, cactus are either awkward to prune, or can not be pruned at all. Barrel cactus have only one or very few round stems. If one of these stems gets to wide, it can not be pruned back. Prickly pear cactus is easier to accommodate only because it has enough stems to spare those that grow out of bounds.

What makes cacti so excellent is their distinctive form. Some have strictly upright stems that resemble those of the organ pipe cactus. Some grow as clumps of short and fat stems. Others grow upward and outward with rounded and flat stems like those of the beaver tail cactus.