Louis Raymond experiments in his own gardens like

a mad scientist, searching out plants that most people have

never seen before & figuring out how to make them perform.- The Boston Globe

…Louis Raymond ensures that trees can grow in Brooklyn…

or just about any other place where concrete consumes

the dirt and skyscrapers shield the sunshine.- USA Today

 
 

NEW Trips to Take!

Myrtle's easy when the conditions are right.

 
 
 
 

NEW Plants to Try!

Louis tries to capture the exact words to describe the fleeting but deep pleasures to be found in these Summer-into-Autumn incredibles.

 
 
 
 

New Gardening to Do!

Allergic to bees? You can still have an exciting garden, full of flowers and color and wildlife.

 
 
 
 

Plant Profiles

Hardy tapioca

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Hardy tapioca has foliage like a shefflera, yet is hardy to Boston.  The flowers are subtle but stylish, too; their interiors are colorful, but only at close range.  They're pendulous, and are appreciated best by bees, which adore them.

 

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Is there any other plant whose leaves have eleven leaflets?

 

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Manihot grahamii is an unusual and yet goes-with-anything tropical tree that, depending on where you grow it and how you choose to handle it, can thrive anywhere from Buenos Aires to Boston.  

 

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Being able to grow as a tree, or a shrub, or a die-back perennial is part of the secret of this plant's versatility.  See "How to handle it" below for ways to take advantage of this elegant and flexible species.

 

Here's how to grow hardy tapioca:


Latin Name

Manihot grahamii

Common Name

Hardy tapioca / hardy cassava

Family

Euphorbiaceae, the Poinsettia family.

What kind of plant is it?

Small tropical tree that, thanks to its ability to drop its leaves as well as resprout from oldest growth or even directly from the roots, can be grown in subtropical climates as a shrub and in warm-temperate climates as a woody perennial.  Evergreen only in frost-free climates.  Unusual hardiness is probably related, in part, to its ready deciduousity:  Manihot sheds it leaves for the "Winter" in climates where Winters are merely cool, not frosty.

Hardiness

Zones 7b - 10.

Habit

Upright but with a quickly-widening canopy of branches and foliage because the tips of ascending stems don't simply send out side branches.  Instead, the tip stops vertical growth entirely as it ramifies into three or four secondary branches, each of equal vigor to the others, and all growing outward at only a modest upward angle.  Whether growing as a small tree, a shrub that experiences regular Winter dieback, or a multi-stemmed returning perennial whose woody stems die to the ground in Winter, Manihot grahamii will still have a characteristic small footprint but wide canopy.

Rate of Growth

Fast.

Size in ten years

Variable, depending on climate and culture.  If growing in a frost-free habitat, a small-boned tree to fifteen or even twenty feet.  Smaller and more shrubby when growing in climates where sub-freezing temperatures are typical.  At the cold end of its hardiness range, a woody perennial that regrows quickly to eight to ten feet each season.  Smaller still when grown permanently, year by year, in a container.  Manihot grahamii is fast-growing enough to be grown as an annual. 

Texture

Lacy and open, thanks partly to the large but very laciniated palmate leaves, and also to the plant's habit of retaining them only at the tips of the quickly-growing branches.

Grown for

its foliage: Round green leaves about six inches in diameter are composed of eleven narrow lobes, and look like the foliage of a miniature schefflera.

 

its fast growth: In a frost-free climate, Manihot can reach full size in a couple of years.  Even as a returning perennial in climates where it is killed back to the roots each Winter, it can soar eight to ten feet by September.

 

its appeal to bees:  Bees besiege the newly-opening flowers but, reportedly, for only about an hour on the morning of their first day of opening—and then vacate the plant for the day.  A large plant of Manihot grahamii that's heavy with blossom will be loudly buzzy for that hour, but silent the rest of the day.   

 

its lack of appeal to browsers:  As is typical for Euphorbiaceae, Manihot has a sticky sap that makes the plant unpalatable.

 

its flexibility:  Depending on the climate and your choices in pruning—see "How to handle it" below—Manihot grahamii can grow in-ground or in a container as a small tree, a shrub, or a perennial.

Flowering season

The apple-green flowers are curious rather than showy, and appear throughout the Summer.  Manihot grahamii plants are self-fruitful, so the flowers of even a solo specimen mature to round pods.

Color combinations

There's a bit of dusky pink on the interior of the flower petals.  But the flowers are small and pendulous, so unless you're studying your plant while lying beneath it while also using a magnifying glass, you're unlikely even to notice, let alone care.  Although the light green of the flowers' exterior, leaf veins, and petioles—plus the mid-green of the foliage interior—go with everything, neighboring plants  make the strongest show if they are predominantly yellow or pale green, and so call attention to the apple-green details of Manihot.  

Plant partners

Neighboring plants to Manihot grahamii synergize with it best when they bring strong contrasts in foliage size, shape, and color.  Whether growing as a tree, shrub, or perennial, hardy tapioca quickly grows tall enough, and wide enough, to create light to medium shade into which the very nearest neighbors will be cast.  So it's best to plant shade-tolerant plants anywhere near the plant, not just adjacent to it.  In any climate, there are many options for contrastingly large foliage, with the larger-leaved plants from just the Aroidaceae and Begoniaceae families, as well as the Aspidistra and Hosta genera, providing hundreds of possibilities in themselves.

 

Despite the overall round shape of the leaves of Manihot grahamii, the lobes themselves are long and narrow, so grassy or sword-like foliage is likely to seem repetitious.  Smaller foliage in simple shapes, whether round or pointed or needle-like, is always welcome; choose shade-tolerant species such as Cephalotaxus, Sarcococca, Ardisia, Trachelospermum, and Vinca.

 

See "How to handle it: Another option—or two!" for suggestions for including Manihot in larger groupings when it or some or all of its neighbors are in containers.

Where to use it in your garden

In Zone 9, Manihot grahamii is a small-scale tree that makes good Summer shade for a terrace; it drops its leaves in the cool season, so the sun can warm the terrace and extend its sitting season.  Grown as a shrub in Zone 8 and a perennial in Zone 7, hardy tapioca is a terrific foliage filler. 

 

In Zone 6 and colder, the plant is valuable as a container specimen or even an annual, because circular palmate leaves of similar size and texture are uncommon in species that are hardy in Zone 6 and colder.  See "How to handle it: Another option—or two!" below for some strategies.

Culture

Sun or part shade, in any reasonable soil.  Good drainage helps hardiness in Zones 8 and 7.  In Zones 9 and 10, the plant is almost too energetic and successfully self-seeding to need special considerations.

How to handle it

In Zone 8 and warmer, you need only plant in Spring, and be alert for the need to yank volunteer seedlings.  Colder than Zone 8a, you'll probably need to cut off tips of branches (or even entire limbs) that may have become Winter-killed.  If you're in doubt about which portions of the plant are alive, wait until new foliage begins to emerge, which will show all too clearly the dead (and therefore leafless) tips and branches that should be removed.

 

If you're growing Manihot as a small tree, prune off lower branches as needed to encourage development of a canopy high enough to bring more open shade to underplantings or, if the tree is shading a terrace, enough head-room for easy sitting.

 

If you're growing Manihot as a die-back shrub or woody perennial, which would be the reality of outdoor cultivation in Zone 8a and colder, it's best to handle the woody growth as you would that of a Buddleja or fruiting fig, Ficus carica:  Let it remain all Winter, cutting down to lowest buds only after new growth begins to emerge the following Spring. 

 

Provide a heavy mulch to help ensure resprouting from the base of old stems or even lower.  Sand is heavy to apply as well as to remove, but has the advantage of retaining much less moisture than a mulch of bark or leaves.  Ultimate success in overwintering in climates colder than the usual limit of 7b is garnered by topping your sand (or dry-mulch) "volcano" with a layer of large pieces of cardboard that have been notched or interleaved so as to allow the woody stems of older growth to project through them while also minimizing the gaps through which icy rain or snow-melt could penetrate.  As with all such "extreme overwintering," keeping the base of the subject plant dry and well-drained is every bit as important as mitigation of extreme cold itself.

How to handle it: Another option—or two!

Many otherwise tender plants that "back home" are shrubs, trees, or returning perennials—in other words, that normally live for years—are too fast-growing to thrive year after year where they are not normally hardy via the usual strategy of growing in a container that is Summered outdoors but moved into shelter the rest of the year.  Even if cut back severely in Spring—and sometimes, with species that are particularly happy to grow as coppices or pollards, especially when cut back severely in Spring—they produce so much growth each Summer that they are almost impossible to keep watered even when growing in larger containers.  Transplanting into a still-larger container only increases the problem:  The plant happily increases in size overall, with its roots now as pot-bound and water-deprived as when the plant was in the smaller container.  And there's a limit to the size and therefore heaviness of potted plants that can be lumbered in and out of shelter, too.

 

In my gardens, Manihot grahamii shares the top of this list with Erythrina x bidwillii, Colquhounia coccinea, Buddleja nivea, Salvia madrensis, Salvia mexicana, and Verbesina microptera.

 

The solution is to grow each in a medium-sized (by which I mean five- seven-, or even ten-gallon; for me, "large" means fifteen- or twenty-five gallon) nursery pot, and to sink the plant, pot and all, in the ground when Summering-out.  The plant's fast-growing roots will quickly escape through the pot's drainage holes into the surrounding soil, minimizing and, in my experience, usually eliminating the need for supplemental watering entirely.  The volume and enthusiasm of top growth is maximized far beyond what is normally possible for the plant when growing in just its container.  At least for that growing season, the plant experiences life as if it were living free-range, top and bottom.

 

In time to return the plant safely to Winter shelter, chop all around the outside of the pot to sever these "summer-escaping" roots.  I start out delicately but, inevitably, soon resort to brute-force stomping all around the perimeter of the pot with a long and straight "poacher's" spade.  Either tie the bulky top-growth together to facilitate such rough-and-ready access or, even easier, cut it off entirely.  Because the plant is being brought into shelter, there's no need for the reverential preservation of top growth that is necessary when overwintering outside. 

 

Sometimes the potted plant can now be freed from the ground with a last heave-ho with the shovel; if the roots that have grown out the center hole in the pot's bottom are thick enough, you'll need to snip them with hand-pruners.  Now, finally, you can lug the potted beast back into shelter.

 

After a couple of years, the nursery pot will begin to buckle and split from the annual exodus of roots that, by the October dig-up, can be as thick as your thumbs.  So what?  Nursery pots are cheap—and, if you do any shopping at all, free with those other shrubs that you've bought.  Don't use fancier or sturdier pots when growing these "Summer-sunk" pots.  The flexible and "buckle-able" construction of the nursery pot is just what's needed to allow the highest volume and thickest growth of the outward-bound roots that will keep the fast-growing plant well fed and well watered through the hottest months.

 

It's not likely that any such summer-sunk container plant will be growing in a bed all by itself.  The neighbors will be hardy, or annuals, or other such "Summer-sunkers."  You need reasonably easy access to "plant" a Summer-sunk pot each spring, and even more when digging it up each Fall.  Help preserve the planting hole for the Fall and Winter, and at least minimize the chore of Spring planting, by sinking an empty place-holder pot at the same location.  Either use a stronger one that won't be caved-in by the surrounding soil, or fill the pot with mulch to give it enough solidity.

 

There's no getting around the man-versus-beast tussle of the Fall dig-up of a Summer-sunk container plant.  Try to leave plenty of room at the back for the inevitable kneeling and grunting.  If pairing the Summer-sunk with annuals, try to choose ones that are more tender, so that they'll be ready to be yanked out entirely before you have to wrestle with the pot.  Happily, the annual warm-weather growth can be so voluminous—I'm thinking in particular of my Erythrina x bidwillii, which grows a dozen and more six-foot stems in all directions when Summer-sunk—that you can leave a two-foot circle of unplanted bed around the pot.  Both it and the pot itself will soon be hidden under the canopy of eager warm-weather growth.

 

Manihot tends to have bare ankles beneath an elevated and spreading canopy, so it's wiser to plant shade-tolerant annuals, at least at the front of the container.  Yellow-leaved coleus would be easy as well as inspired:  The fast-growing canopy of Manihot will provide coleus-friendly dappled shade, and the coleus are available in large enough started sizes to hide the container from the get-go.  Begonia convolvulaceae would work well, too. Or front your Summer-sunk Manihot with an above-ground container plant, preferrably one that is cascading.  Beneath the spreading canopy of Manihot could be the perfect spot to Summer your potted asparagus fern.

Quirks and special cases

The seed capsules are explosively dehiscent, which means that they shatter with enough force to propel the seeds far from the plant. 

Downsides

Manihot grahamii can self-seed abundantly in Zone 9 and warmer.  In such mild climates, the plant will often grow too high to make regular deadheading awkward, too.  Plant with watchful caution to see if self-seeding will be a problem in your particular habitat.  Self-seeding isn't normally a problem in Zones 8 and 7, and neither the plant nor its seeds are hardy in Zone 6 or colder.

 

If using Manihot as a small tree to shade a terrace, consider first that the tree drops its older foliage all through the growing season—and then all remaining foliage during the cooler months.  The regular sweeping up of fallen leaves through the warm months might become tedious.

Variants

I'm not aware of any named cultivars of Manihot grahamii.  There are about a hundred other Manihot species, from trees to shrubs to perennials.  The deeply-cut palmate leaves are typical, as is the sparse foliage canopy.  Only a couple of species—M. grahamii and M. esculenta—seem to have found their way into wide cultivation.  M. esculenta is a woody shrub grown world-wide as a food crop on account of its large starchy roots and protein-rich leaves.  The interior of each lobe of the leaves of M. esculenta 'Variegata' is a bright creamy-yellow; the petioles are red.  Variegated cassava is justly popular as an ornamental in tropical landscapes, and is on my wishlist as a specimen container plant.

Availability

On-line.  Where solidly hardy, anyone who grows the plant will gladly let you dig up seedlings.

Propagation

By seed, and also by division of clumps that result when the plant is grown in climates cool enough to force it to resprout from the roots.  As is typical for Manihot species, the roots are thick and tuberous, and will sprout multiple stems in response to the die-back caused by hard frost.

Native habitat

Manihot grahamii is native to Brazil and Argentina. 

 
 
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