Dividing Perennials Equates To Multiplying

Yuccas can get divided after bloom.

This seems like bad algebra. Horticulturally, dividing and multiplying really are the same. Division is the separation of crowded perennials into smaller but more numerous portions. It multiplies the number of individual plants. The smaller portions perform better than they did while crowded. Division is both a method of vegetative (clonal) propagation, and a form of healthy social distancing.

Many perennials are ready for dividing about now. They finished blooming through spring or summer, and are going dormant for winter. Some defoliate. Division is not so disruptive to them while they rest. Cool and damp weather keeps them hydrated. They can disperse roots and resume growth as winter ends, as if nothing ever happened. They should bloom right on schedule next year.

The most popular perennials grow for many years before getting overgrown enough to benefit from division. Some may technically never need dividing. They manage to perform adequately even as dense thicket growth. For some, division is primarily for propagation. Only a few perennials appreciate annual division. Perennials that bloom in autumn or winter prefer division in early spring.

Pigsqueak will bloom later in winter. Dividing it now with other perennials would inhibit and retard the blooming process. It will be ready for dividing before winter ends, so can settle in with the last winter and spring rain. The same applies to Japanese anemone, which might still be blooming now. Dividing these two perennials is typically for propagation or containment, rather than crowding.

Lily of the Nile and African iris do not need dividing often, but when they do, it can be a major chore. For moderate crowding, it is relatively easy to pluck many individual shoots without disturbing remaining shoots. However, it is typically more practical to dig bulky colonies, divide them into individual shoots, and then plant the shoots. African iris shoots work best in groups of five to twelve.

Lily of the Nile, with dividing earlier than later, disperses roots in winter, to bloom for summer.

Many Perennials Want Seasonal Grooming

Peacock orchid bloom late, but eventually succumbs to frost and must be groomed.

Here on the west coast, autumn and winter weather is so mild that the native coral bells are already starting to develop new foliage on top of the old foliage from this last year. Technically, they are evergreen, so the old foliage does not need to be shed; but if it is not too much to ask, some types look better with a bit of grooming.

Other perennial plants that are from climates with stronger seasons and colder winters are not quite so evergreen. Many shed all of their foliage and are completely bare for at least part of the winter. Only a few, like cyclamen, are at their best through autumn and winter.

Dried watsonia foliage should be removed now if it has not been removed already. It is not so easy to pluck off like gladiola foliage is, so it should be cut off with shears. Because new foliage for next year develops before the old foliage of this past year is completely brown, it is often necessary to cut the old a few inches above the ground in order to avoid damaging the new.

The so called ‘evergreen’ daylilies can be even messier. New foliage is rather delicate, so it is easily tattered by the removal of old foliage. The ‘deciduous’ types may seem to be less appealing because they are bare for part of autumn and winter, but are so much easier to groom by simply removing all of the deteriorating old foliage as soon as it separates easily from the roots.

Deteriorating flowers can be removed from cannas; but their lush foliage can stay until it starts to deteriorate later in winter. Even if it survives winter, it should eventually be cut to the ground as it gets replaced by new growth in spring.

The many different iris have many different personalities. Most should be groomed sometime between summer and late autumn, although Dutch iris were groomed much earlier. Bearded iris that do not get divided can be groomed simply by plucking off big old leaves to expose smaller new shoots below.

Some dahlias bloom until they get frosted. Most though, are already finished. They do not need to be cut back all at once, but can be cut back in phases as leaves and stems dry and turn brown.

Bugle Lily

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Bugle lilies are like lean gladioli.

It would be accurate to guess that bugle lily, Watsonia pyramidata, is related to gladiola. It is not as impressive as gladiola is, but it is much more reliable. The relatively simple blooms become more abundant as bulbs multiply each year. Conversely, after blooming so flamboyantly in their first year, only a few gladiola bloom for a second year.

New bugle lily bulbs (corms) that were planted early last autumn grew through winter to bloom about now, in white and pastel hues of pink, rosy pink, lavender, orange and almost red. The small flowers are neatly arranged on narrow floral spikes that stand about three or four feet tall. The upright and narrow leaves get only about two or three feet tall.

After bloom, foliage slowly browns through warming summer weather, so should be cut to the ground when it becomes unsightly. While bulbs are dormant through summer, they do not need to be watered much, and can rot if soil stays too damp. Crowded colonies of bulbs can be divided and spread around as summer ends.

Figs Are Easy To Propagate

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Some grasses can propagate by division.

The easiest way to propagate new fig trees may seem to be violent, but it works. Basal shoots that grew last year from the roots near the trunks of ungrafted trees can simply be torn out of the ground with as many attached roots as possible. These shoots can then be planted directly wherever new trees are desired, and watered in. Larger shoots may need to be dug out, and might do better if pruned down to just a foot or two tall when planted. Smaller shoots can be potted to grow through next summer, and then get planted in the ground next winter.

Tearing the shoots off in this unpleasant manner is effective for two reasons. It gets the most roots for the shoots to help the grow into new trees. It also removes more of the burl growth that produces the shoots than simply cutting the shoots neatly. Even if copies of the original tree are not desired, the basal shoots must be removed anyway. Simply pruning them away leaves more burl growth so that more shoots grow back next summer. Ideally, well maintained trees should actually not produce basal shoots.

Fig trees are innately easy to grow from basal shoots or cuttings while dormant through winter. Basal shoots, even those that get pulled without any obvious roots, will develop roots more efficiently than stem cuttings that were never in contact with the soil. However, if no basal shoots are available, stem cutting work just fine. Furthermore, grafted trees (which are quite rare) can only be copied by cuttings from above the graft. Basal shoots from below the graft will only produce copies of the understock.

Just as unwanted basal shoots and cuttings from pruning scraps can be grown into fig trees, overgrown perennials in need of thinning can be divided to propagate more of the same. Lily of the Nile, red hot poker, daylily, mondo grass, African iris, terrestrial yuccas, some ferns and some grasses are not only easy to propagate by division through winter, but many perform better if divided every few years or so, before they get too crowded. The common giant yucca develops big trunks instead of clumping shoots, but can be propagated just as easily from big cuttings.

Reassignment

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African iris are happily rehomed.

African iris, Dietes bicolor, that I mentioned three weeks ago were finally installed into a new landscape. It may not be permanent. They may need to be relocated again if they happened to land where two of four birch will be installed as the landscape is slowly assembled before winter ends. The installation was done hastily before the last storm delivered a good dose of rain.

It could not be delayed any longer. These African iris had been divided and groomed so long before they were featured on the fourteenth of December that they were likely to succumb to rot or desiccation if installation was delayed any longer. They soaked in buckets of water for days at a time, and were then left to drain for days at a time so that they would not soak for too long.

I do not remember how many times I repeated the process. I knew it was getting risky. Surprisingly, by the time they were installed, only a few of the worst of the rhizomes were beginning to exhibit negligible indications of rot. Now that they are in moist but fluffy and well aerated soil, they can recover and begin to disperse new roots, even if they must be relocated again later.

If relocated again later, the process will be fast and direct. They will get dug and plugged within minutes. Compared to alternated soaking and draining for more than a month, it will be easy.

The formerly feral birch that will eventually be added to this landscape are also being reassigned. Of nine that were removed from another landscape in the neighborhood, five were already plugged directly into a landscape across the road. The other four were canned temporarily until we determine where they will fit into this new landscape. They will arrive before winter ends.

Lauristinus that formerly inhabited this area were already being reassigned as hedges in other landscapes before we planned to reassign extra African iris and feral birch to this landscape. A few got canned to replace any that do not survive the process. So far though, all have not only survived where they were reassigned, but were growing happily before the weather got cool.

Six on Saturday: Nursery Work

 

This is more like what I should be doing. My part time job here was supposed to be temporary, just until I went back to work growing things. It is not easy to leave. Actually, it is downright difficult. Well, that is another story. Yesterday, Friday, I got to pretend I was back at work, dividing perennials and plugging cuttings. It all came from what already lives in the landscapes.

These seasonal tasks had been delayed until the rainy season started.

1. African iris, Dietes bicolor, got plucked around the edges where it was getting too close to a walkway. These plucked and groomed scraps will be plugged directly where more are desired.P91214-1

2. Lily-of-the-Nile, Agapanthus africanus, got pulled a long time ago, and just left here on the floor. It can get split into many individual pups, but will more likely be planted as a full clump.P91214-2

3. Pigsqueak, Bergenia crassifolia, got pulled where it was creeping over a stone wall. Most was plugged back behind where it came from. Sixteen groups of three pups were canned for later.P91214-3

4. Boston ivy, Parthenocissus tricuspidata, provided this mess when it was relieved of its stakes and groomed. It grew so fast in the first year, that there is concern about planting more of it.P91214-4

5. 100 cuttings is too many! There are only a few concrete structures that it can climb onto. It probably would have been more practical to plug a few cuttings directly into only a few cans.P91214-5

6. Cuttings would have fit better into cans too. These cuttings are plugged diagonally, leaning back toward the top of the picture, with the front row leaning toward the bottom of the picture.P91214-6

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/

Reassignment

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There is quite a bit of open space in some parts of the landscapes. It is not as if the landscapes are lacking much. There just happens to be a few spots where a bit more could be added. This expanse of healthy English ivy was already appealing, but lacked interest.

There is also quite a bit of spare plants out and about in the landscapes. It is not as if there is anything wrong with spare plants. There just happens to be too many of them. These cannas got overgrown and crowded within their original colony in another landscape, so needed to be divided and thinned out.

We are not a so-called ‘landscape’ company, which profits from the removal of some plants, and the installation of others. There is no incentive to dispose of as much vegetation as we could bill a client for. Nor is there any incentive to install as many new and expensive plants as we could fit into any available space. It is not a ‘business’.

To the contrary, it is in our own best interest to exploit resources that are already available to us. For example, when we thinned out these crowded cannas from one situation, we reassigned them to other situations where they could grow and become assets to their new landscapes. Also, viburnums that were removed from one site were reassigned as hedges in other situations.

We will be doing more of this sort of reassignment now that the weather is cooler and rainier, and the plants that will get relocated are dormant. Carpet roses that must be removed from the boundary of a playground because they are too thorny will be relocated to a broad roadside, where they can grow wild. They will be replaced with lily-of-the-Nile that is crowded elsewhere.

Division Renovates Tired Old Perennials

91204thumbAutumn is a time for planting partly because it is when many plants are beginning their winter dormancy. They are, or will soon be, less active than they would be at any other time of year. Some may not start to grow again until after winter ends. Others will want to secretly disperse their roots through the rainy winter weather, while merely appearing to be dormant from above the soil level.

That is why autumn is also the best time for division of many types of perennials. Such perennials should be adequately dormant to not be bothered by the process of getting dug and divided into smaller parts, then replanted. They actually prefer to get it done sooner than later, so that they can slowly disperse their roots through cool and rainy winter weather, and be ready to grow in spring.

Divisions is often done to renovate bulky perennials that have become overgrown, shabby, or too crowded with their own growth to bloom well. Some of the more vigorous perennials may benefit from division for renovation every several years or so. Many complaisant perennials may never benefit from division. Of these, some might be divided merely for propagation of more of the same.

Japanese anemone, bergenia and other perennials that bloom in autumn and winter should get divided later, after bloom. Like perennials that get divided now, they tend to recover and efficiently disperse roots before spring. However, they may need to be watered a bit more than typical if the weather gets warm and dry early next year. Their schedules do not coincide with local climates.

Lily-of-the-Nile, African iris and New Zealand flax can be divided into individual shoots, even if a few shoots get planted together in clumps. Entire plants do not need to be dug if it would be easier to merely pluck a few outer shoots from the perimeters of congested parent plants. Black-eyed Susan and Shasta daisy can be divided into clumps of several dormant basal rhizomes and roots.

‘Pups’, or sideshoots, of agaves and some types of yuccas can be carefully pried from their parent plants without disturbing them.

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.