Perennial Plants Keep On Giving

Can a canna be too perennial?

Many popular annual bedding plants have potential to be perennial if they get a chance. Cyclamen commonly perform as a cool season annual, only until replacement with warm season annuals. However, after summer dormancy, their tubers can generate foliage and bloom again for several following winters. Replacement is just easier than maintenance.

Real annuals complete their entire life cycles, from germination to dispersal of seed and finally death, within a single year. Biennials generate vegetative growth through their first year, and then disperse seed and die during their second year. Perennials perform for at least two years, whether or not they get any opportunities to do so within home gardens.

Home garden culture complicates this classification though. Those who enjoy gardening expect perennial plants to reliably perform for many years or indefinitely. Many perennial plants do so with only minimal intervention. Some are self-sustaining, and might seem to naturalize. That may be why so many smaller or less vigorous types classify as annuals.

Another qualification of perennial plants is that they lack woody stems and roots. In other words, they are herbaceous. Palms and species of Yucca that develop trunks classify as perennial plants also, but for simplicity, the larger types are herbaceous trees. Generally, perennials are terrestrial. A few are epiphytic (live in trees) or lithophytic (live on stones).

Although several perennial plants can survive indefinitely here without intervention, most perform better with some degree of attention. Most ferns are neater if groomed to remove deteriorated fronds. Many grasses benefit from severe shearing during winter. African iris blooms better in response to regular deadheading to remove developing seed capsules.

Perennial plants are very diverse. It is impossible to generalize about their maintenance. One commonality among many is that they multiply. Lily of the Nile can produce so many individual shoots that it can eventually become too congested to bloom. Division of such shoots every several years or so promotes bloom, as well as propagates more plants for elsewhere in the landscape.

Palms Need Proper Planning Too

Every species of palm has a distinct personality. All have attributes; but many also have the potential for considerable problems.

California has no more native palms than Oklahoma has with the diminutive dwarf palmetto. The stately California fan palm, which is also known as the desert fan palm, inhabits warm desert regions in southern California. It is what put the ‘Palm’ in ‘Palm Springs’. However, because it likes heat and minimal humidity, it is not so happy away from deserts. The very tall and lean Mexican fan palm is closely related to the comparably stout California fan palm, but is so happy in local climates that it naturalizes and can be invasive.

The queen palm has a leaner trunk, and a broader and more billowy canopy. It rarely self sows, but is so overly popular that it very often gets planted in bad situation where it does not have room to grow. Unlike fan palms that have rounded palmate leaves that radiate outward from the ends of bare petioles (leaf stalks), the queen palm is a ‘feather’ palm, with pinnately compound leaves comprised of narrow leaflets arranged along stiff midribs.

The massive Canary Island date palm is another feather palm, with a broad canopy and bulky trunk. Like Mexican fan palm, it often self sows, so gets into some weird situations. The foliage is so thick that is commonly becomes infested with rats and pigeons. Female trees produce messy fruit that keeps rats and pigeons well fed.

Whether they get planted intentionally or simply appear in the landscape, the main problem with all these and other large palms, is the expense of maintenance, since they can only be maintained by professional arborists who know how to climb such large branchless trees. Without regular grooming, fan palms that are so often allowed to retain long beards of old leaves become fire hazards, and have the potential to drop dangerously heavy sections of their beards without warning. Removal of old deteriorating leaves from the huge canopies of Canary Island date palms is quite an chore!

There are few small palms, like windmill palm and Mediterranean fan palm, that are more proportionate to compact gardens. Windmill palm has a strikingly shaggy trunk and a compact canopy that is easy to groom before it grows beyond reach. Mediterranean fan palm has multiple trunks that grow so slowly that it takes many decades for them to grow beyond reach. Nasty sharp thorns on their petioles make pruning difficult but not impossible.

Selection of a palm that is appropriate to a particular situation is just as important to limiting serious long term problems as the selection of any other tree is.

Perennial Plants Perform For Years

Perennial pea is similar to sweet pea, but as the name implies, it is perennial.

‘Perennial’ is a simple adjective that describes something that last for more than a single year. Horticulturally, it is not this simple. After all, every plant that is not an ‘annual’, which completes its entire life cycle within only one year, is technically a ‘perennial’. Those that develop lignified (woody) parts instead conform to such categories as tree, shrub or vine.

Even these categories are not as simple as they seem to be. Palms are trees, but without woody stems. Technically, they are merely very large perennials. Some consider them to be ‘herbaceous trees’. Yucca trees conform to the same category; while terrestrial yuccas are usual perennials. Sweet peas are annual vines. Perennial peas are perennial vines.

Many annual bedding plants, such as begonia, chrysanthemum, primrose, cyclamen and even busy Lizzie, are technically perennial. They could survive for a few or several years if they get such a chance. All ferns, including tree ferns, are perennials. So are bamboos, ornamental grasses, and many succulents. ‘Biennials’ are perennials that live two years.

Many of the most popular perennial plants have an indefinite life span. It is impossible to know how long they can survive. They are constantly replacing themselves with new but genetically identical parts. For example, bearded iris migrate and propagate by rhizomes that could have been propagating for centuries. New plants are identical to their original.

However, many perennial plants with potential to propagate indefinitely might eventually get shabby. New Zealand flax, after many years, may slowly migrate outward from where it started growing, leaving a bald spot in the middle. Outer shoots relocate easily to patch such bald spots, or unite as a fresh clump. Crowded lily of the Nile benefit from thinning.

Bulbs and bulb like plants are generally perennial, even if unreliable as such in the mild local climate. (Many bulbs and bulb like plants prefer more chill through winter than they get here.) Most of these sorts of perennials are dormant for part of the year, so die back to the ground. Hostas are bare through winter. Florists’ cyclamen are bare through summer.

African Daisy

African daisy excels as bulb cover.

They are more than just shrubbier and more colorful versions of the formerly stigmatized trailing African daisy. Modern African daisies are actually various hybrids of several other species. Extensive breeding complicated their lineages enough for them to be known by cultivar names rather than by species names. To one degree or another, most are probably related to Osteospermum ecklonis.

These fancier modern hybrids of African daisy grow as annuals in harsher climates. If planted just after the last frost date, they bloom splendidly for early spring, and continue to bloom sporadically through summer. If they grow and bloom a bit too well, they may like to be trimmed back to bloom some more. Locally, they persist through winter as short term perennials, to bloom as winter ends.

Bloom provides pastel hues of yellow, orange, pink, ruddy pink, lavender, purple or white. Early spring bloom is most profuse, particularly for fluffy plants that were not trimmed back over winter. The biggest sprawling plants should get trimmed back after bloom. Subsequent sporadic bloom, mixed with random profuse phases, is inhibited only by warm summer weather and cool winter weather.

African daisy wants full sun and regular watering. Mature plants get about two feet deep and broad. If pressed into the soil, outer stems can develop roots to grow as new plants, as the original dies.

Hobbit’s Pipe

Jade plant has some weird cultivars.

Good old fashioned jade plant has a few interesting cultivars (cultivated varieties) that exhibit variations of color, texture and form. Hobbit’s pipe, Crassula ovata ‘Hobbit’, is similar to classic jade plant in form and color. It is only slightly lighter green, and only a bit shorter. The succulent stems are just as plump and gray. The small and round-topped clusters of pale pink or white flowers that bloom sporadically are just as unimpressive. What is unique about hobbit’s pipe is the weirdly tubular foliage. Each leaf is rolled into a cylinder, with a hollow tip.

Mature plants do not often get much more than two feet tall and broad, although they have the potential to get twice as large. Because they are more sensitive to frost than other jade plants, hobbit’s pipe should be grown in sheltered spots, or pots that can be moved to sheltered spots through the coldest part of winter. Foliage that is too exposed during the warmest weather of summer can get roasted. Hobbit’s pipe can tolerate a slight bit of shade, so can be happy as a houseplant.

Recycle And Repurpose Overgrown Perennials

60720thumbJust like anything else that gets planted in the garden, new perennials seem to be so cute and innocent. They get even better as they mature. Some grow and spread to impressive proportions. Then . . . some perennials get to be too large. Some get overgrown enough to obscure their own appealing characteristics or other plants. Others get crowded enough to inhibit their own bloom.

Lily of the Nile, which is one of the most common and resilient of perennials, grows and blooms indefinitely. It does not spread too quickly, but eventually creeps a few feet every decade or so. However, if it is too healthy, individual shoots can get too crowded to bloom as prolifically as they want to. Also, shoots that get too close to walkways or other plants eventually become obtrusive.

Anyone who has tried to shear encroaching foliage of lily of the Nile knows that doing so ruins the natural lushness of the foliage. Once scalped, it will stay that way until obscured by new foliage that will be just as obtrusive as the removed foliage. The only remedy is to remove the shoots that produce the foliage, leaving the shoots behind them with adequate clearance for their foliage.

Lily of the Nile shoots are not easy to remove. Their rubbery roots have quite a grip! Yet, once removed, the stout stems can be planted as new plants wherever more new plants are desired. They only need to be watered regularly for the first few months until winter, so that they can disperse roots. If dug and replanted in autumn, they generate roots over winter, and are ready to go by spring.

Overly congested colonies of lily of the Nile, as well as African iris and New Zealand flax, can be dug, split into individual shoots, groomed of deteriorating foliage, and then replanted. Because New Zealand flax has such big leaves, it should be processed in autumn or winter; and its leaves should be cut short so that they do not get tattered and floppy while new foliage and shoots grow.

Bird of Paradise can be divided similarly, but carefully because the shoots are surprisingly fragile. However, giant bird of Paradise is a completely different animal. The tallest trunks eventually begin to deteriorate, so get cut down like trees. Basal shoots are left intact to replace them, so only get divided if obtrusive or overly abundant. Most perennials prefer to be divided after bloom.

Canna and calla prefer to be dug and relocated as their foliage dies back after bloom, just before new shoots develop. However, new shoots often develop before older foliage must be cut back.

Creeping Saint John’s Wort

90717This is not the dreaded aggressively invasive Saint John’s wort that has naturalized in other regions. Nonetheless, creeping Saint John’s wort, Hypericum calycinum, does precisely as the name implies. It creeps, and has naturalized to a less aggressive degree in many spots near the coast. Its vigor is an advantage to many landscapes, but might eventually displease adjacent neighbors.

Creeping Saint John’s wort is a somewhat rustic perennial ground cover that does not need much water once established. It naturalizes in coastal climates because it gets all the water it needs from annual rainfall there. Although evergreen, it looks best if mown as winter ends. It happens to be susceptible to rust, and mowing removes much of the old foliage the the fungus overwinters in.

One to two inch wide bright yellow flowers, with five petals and prominent stamens, start to bloom in June and continue into September. By that time, the paired leaves might be getting tired if not watered, or infested with rust, but should stay presentable until mowing at the end of winter. Crowded plants might get three feet high. Otherwise, growth does not get much more than a foot deep.

Zonal Geranium

60525New and improved is not always better. Modern garden varieties of zonal geranium, Pelargonium X hortorum, with bigger, fuller and more profuse blooms, are more colorful than the relatively weedy classic varieties, but they are considerably more demanding. In fact, because they are so unhappy through winter, they are often grown as warm season annuals instead of as perennials.

They are certainly worth growing though, and are reasonably easy to propagate from cuttings. Flowers can be red, pink, white, peachy orange or almost purple. Bloom is almost continuous. Each rounded dark green leaf might be adorned with a darker halo about halfway between the center and the outer margin. Mature plants do not get much more than three feet tall, and not much wider.

Old varieties might get twice as tall, with smaller blooms, and lighter foliage.

Some Annuals Are Really Perennials

90529thumbAnnuals are plants that complete their entire life cycle from germination to death within a single year. Biennials complete their entire life cycle in two years, mostly by developing vegetative growth during their first year, and then blooming, producing seed and then dying after their second year. Perennials are the many herbaceous plants that survive longer than just a few years or indefinitely.

As simple as these definitions seem to be, the plants that they describe are a bit more complicated. Some biennials can regenerate from the roots of plants that have already bloomed and died. Stems of some annuals can root where they touch the ground, to form new plants that survive for another year. Some annuals seem perennial if they replace themselves with their own seedlings.

Of course, none of that matters for the many biennials, perennials and self perpetuating annuals that get grown as mere annuals. At a time when ‘sustainability’ is a fad and trendy buzz word, it is ironic that so many bedding plants that could contribute more if given the chance to do so, continue to get discarded as soon as their primary season finishes. Most have more potential than that.

Self perpetuating annuals like sweet alyssum and nasturtium might only need to be groomed of old plants as new ones take over. Young nasturtium are rather efficient at overwhelming their own parent plants to some degree. Of course, subsequent generations will revert to feral plants. Fancier nasturtium will eventually become basic orange and yellow. Sweet alyssum will be plain white.

Many annuals that are actually perennials might survive through their off season if just overplanted with more seasonal annuals, and then regenerate when the weather becomes more favorable. For example, primrose from last season might be left in the ground as petunias take over for summer, but when the petunias finish next autumn, the primrose can regenerate for another season.

Such perennials regenerate more randomly than they grew in their primary season, and will need some degree of grooming and perhaps mulching.

Perennials Can Divide And Conquer

10810Along with all the bare root fruit trees, roses and cane berries, nurseries also stock bare root perennials like strawberries, asparagus, horseradish and rhubarb. They are so easy to plant while dormant. They recover from transplant through spring, and by summer, should be growing as if they had always been there. Although, if they had always been there, they might be crowded by now.

Yes, many but not all perennials eventually get crowded. Strawberries spread by runners, so are easily plucked and transplanted to avoid overcrowding, as well as to propagate more productive plants. Asparagus are variable, so may not get crowded for decades. Horseradish and rhubarb may not mind getting crowded, but could be more productive if individual plants have their space.

For example, crowded horseradish plants produce many small roots. If dug, split apart, and replanted with more space between individual plants, the individual roots get much larger. Separating the roots, which is known as ‘division’, also produces many more new plants. Mature rhubarb plants may not mind being crowded, but are often divided simply to propagate new productive plants.

Division of these sorts of perennials is typically done while they are dormant through winter. If that sounds familiar, it because it is the same reason why these sorts of perennials are available as bare root stock. They get processed while they are unaware of what is happening, and wake up in their new and better situations. Many defoliate while dormant. However, most are evergreen.

Ornamental perennials like lily-of-the-Nile, African iris, New Zealand flax, society garlic, torch lily, lily turf and acorus grass are all good candidates for division if and when they become overgrown. So are most aloes, some terrestrial yuccas, several ferns and some of the more resilient clumping grasses. Agave pups can be dangerous, but really should not be allowed to get too crowded.

Division might be as simple as taking a few pups or sideshoots from a large clumping plant, or as involved as digging an entire large plant to divide each individual shoot. More often, large plants get dug and split into a few smaller clumps of many shoots. New plants should be groomed of deteriorating foliage. The long leaves of New Zealand flax should be cut in half to avoid desiccation.