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Thrift

Thrift performs well in coastal climates.

When I see common thrift, Armeria maritima, in nurseries now, I wonder what such a diminutive perennial would be useful for. Their densely compact mounds of narrow evergreen leaves rarely get more than four inches deep, and take their time spreading to less than a foot wide. Then I remember how thrift visually softened the straight edges of my father’s brick patio and retaining walls, and fit so nicely into the tight spots. If allowed to do so, thrift creeps slowly over edges of pavement and stepping stones, but is not too eager to overwhelm them.

If it eventually gets overgrown, thrift is easily cut back to the edge of pavement at the end of winter, and will green over its raw edge by spring. The bits and pieces that are left over from cutting back the edges can be plugged back into other areas and will eventually develop roots if initially watered regularly. Once established, thrift stays healthier if allowed to dry somewhat between watering. Bald spots that may naturally come and go as mature plants die out in the center and then regenerate fill in faster if outer edges get cut back.

The dense round clusters of tiny flowers stand above the foliage on bare stems about four to eight inches high. The flowers are almost always bright pink, but are sometimes white or reddish pink. Bloom is most profuse in spring and may continue sporadically all year. 

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Many Pruning Techniques

Proper pruning enhances performance rather than compromise it.

If gardeners can reach it, they will most likely shear it. They do not mind if it was intended to be a shade tree, a flowering shrub or even a sculptural succulent. Few will take the time to prune and groom properly. Ironically, formal hedges that actually need to be shorn are rarely shorn properly! 

Most of us fortunately are not gardeners, but merely enjoy our gardens. We know the importance of proper pruning, and that various plants need different pruning techniques. The main difficulty is determining which techniques are best for each type of plant in our gardens.

Shearing is primarily for hedges; which by the way, should be slightly narrower up high, and slightly wider down low in order to optimize sun exposure to all parts. Generally, plants that are grown for their flowers, fruit or natural form should not be shorn regularly.

Fruit trees and modern roses need the most specialized pruning while dormant in winter, so are not recommended for ‘low maintenance’ gardening. Their specialized pruning thins out superfluous growth, concentrating resources for fruit and flower production. Pruning also removes suckers (from below graft unions) and the ‘four Ds’; which are Diseased, Damaged, Dying and Dead stems. 

Most trees eventually need some sort of pruning to direct their growth. Limbs that are too low need to be pruned away to maintain adequate clearance from roadways, sidewalks, chimneys, roofs and anything else that they should keep their distance from. Lighting, road signs and views from cars coming out of driveways should not be obstructed. As larger trees mature, they eventually need the attention of professional arborists to maintain their health, stability and structural integrity.

Small trees like Japanese maple, Hollywood juniper and pineapple guava look much better with selective pruning and thinning to expose their natural forms. If they become obtrusive, such trees are very often pruned back for confinement. They should instead be pruned to direct their growth up and out of the way, so that lower obtrusive stems get removed, and upper growth can develop naturally.

Nandina, abelia, various bamboos, old fashioned lilac and other plants that produce new stems from the ground benefit from another type of thinning known as ‘alternating canes’. This involves cutting older canes to the ground as they begin to deteriorate or become overgrown. Alternating canes without any other pruning allows nandina to keep its distinctive foliar texture, and abelia to develop its distinctive arching branch structure.  

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Not Ocotillo

Echinocereus engelmannii, hedgehog cactus?

Ocotillo, Fouquieria splendens, was the species that I intended to procure as Rhody and I walked out and into the desert that surrounded the home we lodged at northwest of Phoenix at the end of last April. I had seen it from the roads on the way there. I should have stopped to procure cuttings or small specimens while I had the chance. Furthermore, I should have stopped for cuttings or small specimens as we left without procuring any earlier. It is a fascinating species that I am completely unfamiliar with.

Hedgehog cactus, Echinocereus engelmannii, is all I procured instead. At least I believe that it is this particular species. I really do not know for sure. A few species of the genus are native to the area. This species just happens to be the most common among them, and its description seems to conform to my observations of this specimen. Other species bloom with floral color that is different from that which I observed with a few remaining shriveled floral carcasses. Most other species exhibit different foliar patterns or textures with their spines. This particular species is distinctly more unappealing than the others, but I got it.

Now, I have no idea of what to do with it. First, I should probably wait to see if it survives. The bits that I got might have been a bit too fresh to root before they rot. I suppose that I should remove the developing fruit to divert resources to vegetative growth and root development. I thought that they would abscise naturally after bloom, in response to the distress of separation from the original specimen. I would prefer natural abscission to unnatural intervention. Pruning wounds from such intervention might promote rot while the cuttings are already vulnerable to rot from below.

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Little Leaf Sage

Little leaf sage has little flowers.

Its common name is both simple and descriptive. Little leaf sage is a literal translation of its botanical name, Salvia microphylla. However, several of its most popular cultivars are actually hybrids with other species. Also, they are more popularly but inaccurately known as Salvia greggii. Most lack their species name between their genus and cultivar names.

Little leaf sage is a small and generally evergreen shrubby perennial. Mature specimens are about three or perhaps four feet tall. They are a bit wider, and some can slowly widen by dispersing little rhizomes. Their little leaves are less than an inch long and delightfully aromatic when disturbed. Where winters are cooler, frost might initiate partial defoliation.

Bloom is most abundant for late spring or early summer, and again for autumn. Sporadic bloom can continue throughout most of the year. A few flowers may even bloom through winter. Floral color ranges through red, white and pink, as well as peachy and rosy pink. Coppicing old growth at the end of winter promotes replacement with new basal growth.

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Layering Can Copy Favored Flora

Ivy can grow roots almost anywhere.

Seed is the most familiar method of propagation. However, some popular plants produce no viable seed. Some produce seed that is genetically very different from its parents. For many plant varieties, only vegetative propagation reliably produces similar copies. Such copies can grow from division, cuttings or layering. They are genetically identical clones.

Layering is uncommon for nurseries because it is generally insufficiently productive. It is unpopular for home gardening because it seems complicated. It is actually more reliable for many species than cuttings are. Also, layering is quite practical if merely a few copies are sufficient for home gardening. Realistically, it is not as complicated as it seems to be.

Layering is simply the development of roots where stems lay on the soil. All sorts of flora does it naturally without intervention. For example, ivy vines notoriously develop roots as they extend over the ground. Tips of raspberry canes develop roots where they leap over to reach the ground. These rooted tips grow replacement canes that repeat this process.

With a bit of intervention, several species that do not commonly layer can do so also. For some, it can be as simple as pressing a lower stem into moist soil. Application of rooting hormone to exposed cambium accelerates layering for most. Gouging into the underside of the buried portion of stem exposes its cambium. Tip growth must remain above grade.

For most species, the buried portions of layering stems should be a few inches in length. Extra stem length is no problem. Actually, if stems are long enough, they can be situated into their permanent locations. Stems can layer right below grade, but they prefer to be a few inches deeper. While their roots develop, they require irrigation for evenly moist soil.

The few inches of foliated tip growth above grade sustains actively layering stems. Also, remaining intact cambium provides sustenance from the original plant. Only a few stems can layer simultaneously, but that is enough for most gardens. Hydrangeas, azaleas and camellias layer quite easily. Pines, oaks and eucalyptus do not. Layers should develop quite a few roots before separation.

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Going Bananas! II

‘Double Mahoi’ banana pup with pups

‘Double Mahoi’ banana has been tediously slow. Although I now know why, I am disappointed with its development so far. After the primary pup that I split from the original last year got frosted over winter, I noticed that its central bud survived and was barely beginning to recover. Then, it stopped. I mean, it did nothing for several days or maybe more than a week, even though the weather was warming. Also, the foliage remained pale, as if it had just emerged. Because it was stagnating for so long as the weather was warming, at least one of its leaves got scalded in the middle. Then, because I gave it a bit too much soluble fertilizer, its leaves got bad tip burn. I suspected that it was up to something while seemingly inactive, but did not really know. Finally, the tip of its first pup appeared. Then another appeared, and then a few more! While still just a pup, it had an entire litter of eight pups, which is four times ‘Double Mahoi’, and I do not know if it is finished. Of course, eight pups sharing resources do not grow fast. Also, the tip burn continued as the pups initially emerged, which likely inhabited growth for a while. For now, I can only give them plenty of water, and refrain from giving them more fertilizer. They have good exposure, but I will move them under saran if the weather gets too warm for such small pups to be so exposed. I doubt that all eight pups will survive, but I would have been pleased with merely one. Of course, the one original pup will not survive the process of diverting its resources to its pups, but that is an acceptable consequence of getting a bit more than expected.

Original ‘Double Mahoi’ pup not much more than a month ago
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Big Lemons

Ungrafted ‘Eureka’ lemon

All but two of the forty or so cultivars of citrus that I grew in the early 1990s were grafted onto the same dwarfing shaddock rootstock. Only ‘Meyer’ lemon and ‘Seville’ sour orange were not grafted, or ‘on their own roots’. ‘Meyer’ lemon naturally stays compact enough to not need a dwarfing rootstock. it was our most popular cultivar. ‘Seville’ sour orange supposedly grows about as large as the various dwarfed sweet orange with or without a dwarfing rootstock, as if the rootstock does nothing to limit its ultimate size. It was our least popular cultivar.

‘Eureka’ lemon, ‘Lisbon’ lemon and ‘Sanguinelli’ blood orange grow larger than any of the other grafted dwarf citrus that we grew. ‘Eureka’ lemon is actually a variant cultivar of ‘Lisbon’ that produces fruit throughout the year, which is a desirable attribute within home gardens. ‘Lisbon’ lemon may seem to be a bit more productive, but only because it produces all of its fruit within a more defined season, which can be a desirable attribute for orchard production. Otherwise, ‘Eureka’ and ‘Lisbon’ lemons are indistinguishable from each other, and grow quite tall. ‘Sanguinelli’ blood orange grows about as large, with a nearly identical upright form, but with a softer foliar texture.

Without dwarfing understock, ungrafted ‘Eureka’ and ‘Lisbon’ lemon trees can grow as big as small shade trees, and produce more fruit than they can support against gravity. Their broken limbs are a horridly thorny mess to clean up. ‘Sanguinelli’ blood orange trees can grow about as large, although they support the weight of their fruit more efficiently, and any debris that they generate, hopefully from pruning rather than breakage, is not so objectionable to handle.

So, I should have known better than to plug a bunch of ‘Eureka’ lemon cuttings. As cuttings, they lack dwarfing understock. I shared more than half with neighbors, who have been warned. About fourteen remain. One is more than enough.

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Six on Saturday: Surprise

Surprise is a town northwest of Phoenix that I encountered between late April and early May. These six are different sorts of horticultural surprises which I encountered at work.

1. Platycerium bifurcatum, common staghorn fern, Tillandsia usneoides, Spanish moss and two other unidentified species of Tillandsia combined for a surprisingly compelling epiphytic platter. The staghorn fern is from Brent’s garden. The Spanish moss should be fuller as it grows. The two unidentified Tillandsia should be displaced as the fern grows.

2. Brugmansia X cubensis ‘Charles Grimaldi’ angel’s trumpet is no surprise. A picture of it posted here last Sunday. Its richer than typical yellow floral color is a surprise though. It is also from Brent’s garden, and was from one of his projects years ago. Brugmansia X candida ‘Double White’ and Brugmansia suaveolens ‘Single White’ both bloom nearby.

3. Brugmansia, angel’s trumpet of an unidentified cultivar demonstrates why the yellow floral color of ‘Charle’s Grimaldi’ is so surprising. Both were about the same pale peachy color last year, with the same fragrance. I thought that they may be the same. Obviously, but actually surprisingly, they are not. I do not know what it is, but I know what it is not.

4. Persicaria amplexicaulis ‘Firetail’ arrived here with Persicaria bistorta ‘Superba’ and perhaps Persicaria affinis ‘Dimity’ from Tangly Cottage Gardening early last April. I can not distinguish the cultivars, which is why I do not know if they include ‘Dimity’. It was a surprise to see ‘Superba’ bloom immediately after relocation. ‘Firetail’ is a surprise now.

5. Mimulus guttatus, seep monkey flower is blooming with surprising abundance where the stream from Redwood Springs flows into the drainage pond. The location should not be a surprise since, as its common name implies, this species prefers damp situations. It is surprising only because I somehow neglected to observe so much bright yellow earlier.

6. Rosa, rose of an unidentified cultivar would not be so surprising if I were not aware of how it got here. Someone who does not work in the landscapes removed it from where it was obstructing access to one of his projects. I saw it in his pickup as he was about to discard it. I am surprised that it survived, blooms well and seems to be a hybrid tea rose.

This is the link for Six on Saturday, for anyone else who would like to participate: https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/

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Clematis

Clematis like warm air but cool soil.

Like the big bark of a little terrier, the big and boldly colored flowers of large-flowered hybrid clematis seem to be more than their delicate vines should be able to produce. Almost all of the many modern varieties bloom with flowers that are at least three inches wide; and some have slightly ruffled double flowers. Their rich, deep, and sometimes two toned shades of red, blue, purple or pink, as well as white seem too opulent for their simple wiry stems that may climb to only six feet or so. The dark green compound leaves grab harmlessly onto light trellises, stakes or lattice.
Although the foliage and flowers want sunny exposure, clematis roots do not like warm soil, so appreciate generous mulching.  Some people like to give them a wide rock to disperse their roots under, or plant them next to large pots that sit directly on the soil. I planted mine on the north side of the northwestern corner of the house where the soil was always shaded, and allowed it to climb around the corner onto an iron banister on the west side.

Clematis want to be watered and fertilized regularly, and well drained organically rich soil. They should be pruned rather aggressively in winter while they seem to be dead, but are really just dormant.

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In The Zone

Climate is regional.

We all know how excellent the local climate is for gardening. As we travel around the area though, we also realize that there is more than one climate. Locally, there are at least three of the standardized ‘Sunset’ garden zones, with several more within only a few miles. There are countless microclimates too.

Elevation, terrain, latitude and the proximity of the ocean or large bodies of water all influence the climate. Even though the Santa Cruz Mountains are not very high, they sometimes get snow on top because higher elevations are a bit cooler. When the Summit and Santa Clara Valley floor are cold in winter, the slopes in between are not quite as cold because cold air drains away downhill. The areas closest to the San Francisco Bay stay much cooler through summer because of the insulating quality of the water. 

More localized variables like forests, lakes, direction of slopes and infrastructure affect microclimates. Older neighborhoods with mature trees are shadier and cooler than newer neighborhoods with smaller trees. The west facing slopes to the east get warmer than the east facing slopes to the west. In Downtown San Jose, tall buildings create cool and shady microclimates to the north; and some reflect enough solar radiation to significantly warm areas to the south and west.

It is important to know what climate zone any particular garden is in to be able to select appropriate plants. Besides that, it is important to know the microclimates within the garden to know where each plant will be happiest. Tropical plants that would be happy in Los Angeles might succumb to even mild local frosts. However, plants that might succumb to frost if too exposed may be safe in sheltered microclimates.

Generally, Campbell, most of San Jose, southern Sunnyvale, northeastern Cupertino, northeastern Los Gatos and Union City are all within Sunset Zone 15. Most of Saratoga, southwestern Los Gatos, southwestern Cupertino and Mission San Jose are in Zone 16. Santa Clara, Alviso, Milpitas, northern Sunnyvale and western Fremont are in Zone 17.

None of these zones are too severe. Because of the marine influence of the San Francisco Bay, Zone 17 can actually be relatively boring and not so great for plants that want winter chill or summer warmth. Zone 16 is very similar to Zone 15, but comprises hillside thermal belts where cold air drains away in winter, and also gets a bit warmer in summer. Above and below Zone 16, Zone 15 gets cool enough for plants that want winter chill, but may not get warm enough in summer for plants that crave heat. The Sunset Western Garden Book not only describes the climate zones in detail, but also specifies what zones every plant is adaptable to.