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Warm Season Annuals Are Hot

Petunia will enjoy warming spring weather.

Cool season annuals were cool just a few months ago. Now, it is getting to be about time to warm up to warm season annuals. They will become a hot commodity as winter yields to spring. Many begin to bloom with warming spring weather, and continue to bloom until autumn. Then, as the weather cools, they relinquish their space to cool season annuals.

Warm season annuals, or summer annuals (or warm season or summer bedding plants), are technically a bit early for a few regions. They should wait until after the last frost date, which might be later in the month for some climates. Even where frost is no threat, it may be too early to replace cool season annuals that continue to perform until spring weather. 

Warm season annuals only seem to be seasonable now because the weather has been so pleasantly mild and even warm. Some cool season annuals are already beginning to deteriorate, which facilitates their replacement. Warm season annuals might dislike cool nights and short days, but should appreciate the opportunity to disperse their roots early.

However, some degree of risk is associated with early planting of warm season annuals. Mild frost, although unlikely, is still possible in some climates, and could necessitate frost protection for vulnerable plants. Resumption of rainy and more typically wintry weather is more likely. Heavy rain can thrash fresh bloom. Sustained dampness can cause mildew.

Like warm season vegetable plants, warm season annuals can grow from seed or small plants from cell packs or little pots. Some prefer to grow directly from seed. Others prefer transplanting. Nasturtium, for example, prefer direct sowing. Petunia, which perform well after transplant as seedlings or small plants, are likely to languish if they grow from seed. 

Because seed take a bit of time to germinate, they can go into the garden slightly prior to the last frost date, and earlier than vulnerable seedlings. Similarly, they can start within a greenhouse early for later transplant. With proper scheduling, frost should no longer be a problem by the time seedlings emerge above the garden soil, or are ready for transplant. More variety is obtainable as seed.

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My niece loves Reneesgarden.com!

My neice finds seeds for most of her favorite vegetables, flowers and herbs, like this prolific chamomile, at Renee’s Garden.

Even after a few years of trying most of the seeds available from Renee’s Garden Seed catalog, my niece still wants to grow them all every year. Sadly, her compact garden and landscape designer father who thinks he owns it can not accommodate all the seeds that she wants. She is therefore forced to limit selection to her favorites and those that she has not yet tried.

‘Cupani’s Original’ and ‘Perfume Delight’ are still her favorite sweet peas because they are so very fragrant. The big softly blushed pale yellow flowers of ‘April in Paris’ are a close second. Although not as fragrant, I wanted her to try ‘Electric Blue’ for its shaggier darker green foliage and smaller but refined deep blue flowers.

Perhaps as a strategy for an alliance, my niece’s oppressive father planted ‘Buttercream’ nasturtiums, which was a new variety with semi-double cream colored flowers. She rebelled with the brilliant red shades of ‘Copper Sunset’. The softer orange shades of ‘Creamsicle’ was a diplomatic compromise.

Both could agree on the soft lavender and pink shades and white of ‘Gulf Winds’ alyssum, the rich deep pinks of ‘Mountain Garland’ clarkia, and the traditional ‘Mrs. Scott Elliot’ columbine, since all three are so complaisant with mixed annuals and perennials. Taller and more vigorous cosmos got their own space. ‘Dancing Petticoats’ provided a mixture of cheery pink shades. ‘White Seashells’ looked sharp against the deep green privet hedge.

Since utilitarian vegetable plants are inconsistent with such a designer landscape, my niece grew vegetables that are as flashy as foliage plants. I suggested richly colored ‘Scarlet Charlotte’ chard, with a bit of ‘Italian Silver’ that exhibits distinctive white petioles and veins. She went for the more colorful ‘Garden Rainbow’, ‘Neon Glow’ and ‘Bright Lights’.

Some (but not all) of Renee’s Garden vegetable seed mixes have a distinct advantage of color coding. The various seeds withing these mixes are dyed with different colors so they can be planted separately if desired. Since seed packets usually contain more seeds than are actually needed, vegetable seed mixes are a practical way to get fewer but enough of a few different types of seed in single packets.

More varieties of seeds are available from the online catalog of Renee’s Garden Seed at www.reneesgarden.com than at retail nurseries. Yet with so many fun varieties to try, the retail seed racks certainly have more selection than any garden really needs. If it were at all possible to try them all, my neice would have figured out how to do it already.

Posted on by tonytomeo

Warmth Accelerates Early Spring Bloom

Deciduous fruit trees should remain dormant.

Unseasonable warmth and dryness has been great this winter. Such weather is often an advantage of this locally mild climate. Chill never gets too harsh. Rain does not continue for too long. However, even by local standards, the weather has been unusually dry and warm for quite a while. Although appealing to people, it can get disruptive horticulturally.

Obviously, a lack of rain eventually becomes a lack of moisture. Some evergreen plants, potted plants, ground cover plants and lawns may already need watering. Although rain, or lack thereof, does not affect availability of water from municipal sources, it determines when irrigation with such water becomes necessary. It will be sooner than later this year.

Obviously, warmth accelerates this process. It draws moisture both from intact evergreen foliage and the soil below. (Dormant deciduous plants still do not lose as much moisture without foliage.) Unseasonable aridity (minimal humidity) and wind intensify the effect of unseasonable warmth. Desiccation is not the worst consequence of the weather though.

Unseasonable or premature warmth might stimulate premature spring bloom and growth. This can be very disruptive for plants that rely on sustained chill to maintain their minimal dormancy requirements. Peonies that are marginal where they normally experience their minimal chill requirements might be dissatisfied with inadequate chill through this winter. 

Even for plants that do not require much or any chill, premature bloom can be vulnerable to normal aspects of wintry weather if and when it resumes. Flowering cherry trees might bloom during sustained warmth. Such bloom would be quite susceptible to damage from resuming winter rain. Resumed chill might stall premature magnolia bloom until it molds. 

Prematurely developing fruit, accelerated by unseasonable warmth, is also vulnerable to resumption of wintry weather. Heavy rain, which is still possible through the remainder of winter, can dislodge freshly pollinated flowers, or small fruit as it begins to develop. More developed fruit is vulnerable to rot or mold during cool and damp weather prior to spring.

Posted on by tonytomeo · 3 Comments

Prune now for roses later.

Roses should be pruned before the end of winter. Here where winters are so mild, they can get pruned early.

Just like most of the modern fruit trees that were bred over the past few centuries to produce unnaturally large and abundant fruit, almost all modern roses have been bred for unnaturally large flowers. Production of such large flowers takes quite a bit of work. An excess of these large flowers is more than overgrown rose plants can keep up with. This is why roses should be pruned so aggressively while dormant in winter.

Pruning should be done before buds start to swell at the end of winter. Some people prefer to wait until the end of February. However, because winters are so mild here, buds are already starting to swell, and some are even beginning to grow. I actually prefer to prune early, as soon as roses are dormant and most of the foliage falls off easily when disturbed.

The objective of pruning is to remove as much superfluous growth as possible, in order to concentrate growth into fewer but more productive stems and flowers. Without pruning, roses naturally develop into rampant thickets of abundant but less productive stems. It is also good horticultural hygiene to remove all foliage from last year, since that is where fungal and bacterial pathogens overwinter. Leaves should be plucked from stems and raked from the ground.

Hybrid tea roses get pruned severely so that there are only three to six canes about two feet high. Healthy canes that grew from the base last year are the best. They should have fresh green bark, and preferably lack branches below where they get pruned. Older canes that are developing striations (rough bark texture) should be pruned out. Most floribunda roses can get pruned almost as severely, so that they have only five to a dozen canes.

Some grandiflora roses are allowed to get significantly taller. They develop most new canes on top of canes that were pruned during the previous winter, instead of from the base. Consequently, some stems can get quite old and tall before new basal canes develop to replace them. Climbing roses are likewise pruned less aggressively, since new canes grow from old canes.

Like most fruit trees, most roses are grafted. Therefore, ‘suckers’ (shoots from below graft unions) must be removed. Tree roses should not be pruned below the graft unions on top of their main trunks. Most carpet roses are not grafted, so do not develop suckers; but then, they do not require such specialized and aggressive pruning either.

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Pollarding Pruning Techniques Remain Controversial

Pollarding is pruning to the extreme.

Olive orchards formerly inhabited some of the regions that became urban in California. A few orchard trees remained within urban gardens of the homes that encroached on them. Unfortunately, for those who did not utilize the abundant olives, these trees were horridly messy. Many decades ago, pollarding eliminated the mess without eliminating the trees.

Pollarding is extreme pruning that eliminates all but the main trunk and a few main limbs. It deprives olive trees of their ability to bloom, by eliminating stems of a previous season that would otherwise bloom during the next season. Fruit can not develop without bloom. For other trees that bloom only on older stems, pollarding eliminates bothersome pollen.

Pollarding has several other practical applications. It confines trees that would otherwise get too big for their respective situations. It enhances foliar color and texture for trees that display colorful foliage through summer, such as Schwedler and Princeton Gold maples. Red twig dogwood generates more colorful twigs, and more abundantly, after pollarding.

For agricultural purposes, pollarding generates lush vegetative growth of white mulberry to sustain silkworms, or other vegetation for livestock. It similarly generates long and thin willow stems for basketry. Various eucalypti rely on pollarding to produce juvenile foliage that is colorful and healthy enough for floral design, or aromatic enough for essential oils. 

Nowadays, pollarding is unfortunately passe and even vilified. Consequently, almost no arborists learn about it. Because it is technically disfiguring and potentially unsightly, it is undesirable for many situations. Annual repetition is needed to prevent bloom or fruiting. Otherwise, restorative pruning or more extreme pollarding eventually become necessary. 

For pollarding, proper technique is imperative. Such severe pruning must happen during winter dormancy. It would it be too stressful during vascular activity. Besides, bark would be very susceptible to scald if so suddenly exposed during warmer and sunnier weather. Pruning cuts must be very neat, and back to any old pollard cuts, without stubs to inhibit healing.

Posted on by tonytomeo · 6 Comments

Only Arborists Specialize In Trees.

Big trees need real arborists. Even the best of gardeners should not be expected to perform major specialized arboricultural techniqes.

Just as most problems in landscapes are caused by maintenance gardeners hired to maintain the landscapes, many of the problems with trees are caused by those hired to fix such problems. Arboriculture, which is the horticulture of trees, really should be performed, or at least directed, by professional arborists. It is too specialized to expect it to be done properly by those lacking education and experience.

Even the few proficient gardeners who can perform most aspects of gardening well are not likely as proficient with proper arboriculture as arborists are, not only because it is so different from other gardening, but also because of the techniques and tools involved. Gardeners compare to arborists something like those who clean windows on skyscrapers. Custodians who clean windows on the highest floors from the inside probably would not want to clean the same windows from the outside like window washers do. There are just too many differences in the two related but vastly different types of work.

Arborists who are certified by the International Society of Arboriculture, or ISA certified arborists, are the most qualified to assess the health, stability and structural integrity of trees, and to then prescribe any necessary arboricultural procedures. These arborists have passed an examination of their arboricultural expertise, and maintain their certification by continued involvement with ISA educational seminars, workshops and classes.

Arborists and the tree service businesses that they are affiliated with are easy to find at the website of the ISA at www.isaarbor.com. They can be found directly by name, or regionally by city or ZIP code. The website is also an excellent resource for those wanting to learn more about trees and the importance of proper arboriculture.

Trees are the most substantial features of landscapes, and are really worthy of more respect than they commonly get. Structural problems or instability can be serious problems, not only to the affected trees, but also to anything around them that might be damaged or destroyed by falling limbs or even entire trees. Proper arboriculture helps to keep trees healthy and reasonably safe for many decades or centuries.

Posted on by tonytomeo · 8 Comments

Late Bulbs Require No Chill

Cannas grow after spring bulbs bloom.

Spring bulbs are making a comeback from their unceremonious internments last autumn. Some of the earlier sorts are visibly extending foliage above the surface of the soil. A few narcissus, daffodil and crocus are already blooming! Now it is time to plant late bulbs, or summer bulbs, which start to grow through warm spring weather, and bloom for summer.

Spring bulbs are generally the same as hardy bulbs of climates with cold winter weather. They are hardy to frost while dormant. Since chill is relatively mild locally, their hardiness is irrelevant. Conversely, some prefer more chill than they experience locally. Inadequate chill can compromise performance. Autumn planting maximizes their brief chill exposure. 

Late bulbs are completely different from spring bulbs. Not only do they not require chill to perform, but some dislike it. Many of the most popular late bulbs that can naturalize here succumb to frost elsewhere. Instead of early planting for chill, as spring bulbs prefer, late bulbs prefer late planting to avoid chill. Their foliage emerges after the last threat of frost.

However, although they do not need or even appreciate chill, most popular late bulbs are resilient to the minor chill of local climates. Once established, they simply die back to the ground in response to the first frost of autumn. They maintain dormancy through winter to regenerate for spring. Some repeat this process for years, since the soil does not freeze.

Not all late bulbs are actually bulbs. Most are corms, rhizomes, tubers, tuberous roots, or other bulb-like perennials. Some, such as dahlia and canna, bloom through an extensive season. Some, such as lily and gladiolus, bloom only once. Planting in phases for a few weeks prolongs their bloom. Of course, they will synchronize for any subsequent bloom.

Canna and common white calla are two of the most reliable late bulbs. Crocosmia is too reliable, and since it can be invasive, it is rarely available. Common gladioli and various lilies are spectacular in bloom, but not reliably perennial. Dahlia is a very rewarding and reasonably reliably perennial summer bulb. It is spectacularly variable in color, form and texture.

Posted on by tonytomeo · 8 Comments

Air Layer Overgrown Houseplants.

Air layering big houseplants, like these lanky rubber trees, keeps them proportionate to limited space while also propagating new plants.

Most of the favorite houseplants are grown for dense evergreen foliage. Stems of Chinese evergreen, anthuriums, bromeliads and most ferns should never be seen. Yet, there are many houseplants that grow like small trees or coarse vines. Various ficus, dracaenas and philodendrons can get too big for their situations if not pruned. Palms can not be pruned down, so can only be moved or given to friends with higher ceilings.

Pruning and discarding overgrown but slowly growing stems seems like such a waste. Technically, stems from almost any overgrown houseplant can be rooted as cuttings. In reality though, most rot before they develop roots.

‘Air layering’ is probably the most efficient technique of propagation of houseplants from overgrown stems. It involves rooting the stems while still attached to the original plant. In the end, an unwanted stem gets pruned away as a freshly rooted new plant.

Air layering needs a bare and manageable section of stem that is at least a few inches long. This section does not necessarily need to be where the stem will eventually get pruned away from. It can be a bit higher (or farther out from the origin) if a shorter copy (new rooted plant) is desired. The extra length of stem in between can be pruned out when the copy gets separated.

The stem should be notched up to a third of the way through. This notch will develop roots better if rubbed with rooting hormone. A big wad of wrung out damp sphagnum moss a bit larger than a softball then gets wrapped around the notch, and then wrapped in plastic film. A cut up freezer bag should work nicely. The bag should be held in place with plant tie tape or something as simple as electrical tape, wrapped firmly around the stem above and below the sphagnum moss. Smaller stems can get smaller wads of sphagnum moss.

Unfortunately, there is no way to disguise the unappealing wrapped moss during the few months that may be needed for roots to develop. Eventually, roots become visible through the plastic, or the moss becomes firm with roots. The newly rooted stem can then be cut below the roots, unwrapped and potted as a new copy of the old houseplant. The stub below can be pruned away, or left to develop new shoots.

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Citrus Trees Are Dutifully Fruitful

Citrus are most abundant through winter.

Winter is the primary season for citrus fruits. Some ripen significantly earlier. Some ripen significantly later. Many citrus trees continue to produce a few fruits randomly throughout the year. Nonetheless, citrus fruits are collectively most abundant during winter. It seems odd that trees that are vulnerable to frost are so productive during the coolest of weather.

Citrus trees are fortunately only marginally susceptible to frost in only the cooler climates here. They mostly recover from minor damage where they get a bit too much chill. Those in coastal climates may never experience damaging frost. Some types of citrus are more resilient to frost than others. Vulnerable citrus trees may need frost protection when new.

Home garden citrus trees are different from orchard trees. Most orchard trees, particularly older trees, are ‘standard’ trees. They grow on standard rootstock that allows them to get larger, and therefore produce more fruit than ‘dwarf’ trees. Most home garden citrus trees are ‘dwarf’ trees. They grown on dwarfing rootstock that keeps them dense and compact. 

Furthermore, the many cultivars of citrus that are available for home gardening are more diverse than those that commonly grow in orchards. ‘Lisbon’ lemon is very profuse within season, so is preferable for orchards. ‘Eureka’ lemon, although a bit less productive, may be a preferable option for home gardens because it produces a few random fruit all year.

Now that citrus are in season, some last longer than others. Grapefruit can hang on their trees for months. They actually develop richer flavor with mellowing tartness as they age. Conversely, Mandarin orange and tangerine are the most perishable citrus. Because the rind is loose, their pulp within begins to oxidize after ripening. Lime eventually gets pithy. 

Although this is the time of year to enjoy fresh citrus fruits, it is not the season to do much else with citrus trees. Pruning and application of fertilizer will be more timely after winter. Premature pruning or use of fertilizer is likely to stimulate premature growth. Such growth either languishes through cool weather, or succumbs to mild frost.

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Christmas Leftovers

Blue spruce is a good choice for a living Christmas tree, since it can be happy for years in containment.

Just three weeks after Christmas, many of us are already wondering what to do with poinsettias, cyclamens, Christmas cacti, hollies and living Christmas trees. Christmas cacti and hollies are perhaps the easiest of these to accommodate. Christmas cacti do not even need to leave the home as their flowers eventually deteriorate, since they are happy as foliar houseplants or potted on sheltered porches, and with good sun exposure, will bloom annually. Hollies make handsome shrubbery where their prickly foliage will not be a problem. Since some hollies get quite large, and others stay low and compact, it is helpful to know which variety any particular holly plant is.

Cyclamens are popular as cool season bedding plants as well as blooming potted plants. Gardeners typically dispose of those grown as bedding plants as if they were mere annuals. However, they are actually cool season perennials that go dormant through summer. If they are not in the way of warm season annuals in spring, and are among other plants that will cover for them during their dormancy, they can be left in the garden to regenerate and bloom again next winter. Individual potted plants that get too tired to be appealing in the home can be retired to partly shaded shallow ground cover or mixed perennials for a bit of winter color.

Poinsettias are a bit more complicated, which is why so many people simply discard them as they slowly lose their color after Christmas. They can keep their color for many months, and be happy as houseplants, but rarely bloom again in the home once their first bloom is gone. Alternatively, they can be planted into sheltered and partly shaded spots in the garden after frost. Through summer, they develop taller scrawny stems that bloom early in January or so. (Yes, they bloom ‘after’ Christmas.) They are sensitive to frost, so like to be under eaves.

Of all the popular potted plants associated with Christmas, living Christmas trees are the most problematic, not because they are difficult to care for, but because they so often get planted in bad situations. Only the compact conifers, like spruces, junipers and Scots pines, can stay potted to function as Christmas trees for a few years or more. Almost all other pines grow too vigorously to be happy for long in containers. After Christmas, they should instead get their circling roots severed, and then be planted into the garden.

The problem is that most living Christmas trees are Italian stone pines or Canary Island pines, each of which gets much too large for confined garden spaces. If there is not enough space for such a tree to grow to maturity without causing trouble, it best to find another home for it, or to discard it when it outgrows containment.