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

Rattlebox

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What garden isn't more interesting because of the white, yellow, pink, or lavender flowers of plants of the pea family, Fabaceae?  So far, I've written on Albizia, Caesalpinia, Caragana, Cassia, Galega, Genista, Gleditsia, Indigofera, Lespedeza, Phaseolus, Sophora, and Wisteria.  Here's yet another—with red and orange flowers.

 

Sesbania tripetii couldn't be easier.  Although it's a shrub or even a small tree, it grows so fast you can use it, like I do, as a flowering annual.

 

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The racemes of lipstick-red buds open to orange flowers; there's also red in the stems of the leaves.

 

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This tree's ability to flower only months after germination, quickness of growth, and poisonous seeds make it a weed in climates where it's hardy.  The common name, rattlebox, comes from the dried seed pods.  They hang on the branches in the winter, and the seeds they contain rattle in the wind.

 

There's no danger when growing Sesbania tripetii in climates cold enough that the plants or (scarce) seeds can't survive the winter.  There are plenty of other flowers with orange and red flowers for the tropics, but precious few farther north.  

 

 

Here's how to grow this summer-flowering tree:


Latin Name

Sesbania tripetii /  Sesbania punicea

Common Name

Rattlebox

Family

Fabaceae, the Pea family.

What kind of plant is it?

Deciduous shrub or small tree.

Hardiness

Zones 7 - 10.

Habit

Shrubby or, where solidly hardy, a small tree. 

Rate of Growth

Extremely fast.

Size in ten years

A large shrub or small tree to fifteen feet high.  When grown as an annual, a shrub to three or four feet tall.

Texture

Lacy.  If you're tired of combating Sesbania that has become established where it is hardy, you may find "thin and weedy" a more appropriate descriptor.  The foliage casts only dappled shade, and the branching is open.

Grown for

its flowers: Short racemes of red-orange buds, brilliant in themselves, open to still-brighter orange flowers.  A new raceme emerges from the base of each new leaf.  


its eagerness to begin flowering: S. tripetii can begin flowering two or three months from germination, so the tree can also be grown as a colorful annual.

Flowering season

The plant remains in bloom as long as it is in active growth, and that can be months.  Where S. tripetii is hardy, an established plant can flower from Spring through Fall.

 

If seeds are germinated in a greenhouse in March, young plants will already be in flower when set out as warm-weather annuals in mid-June.  

Color combinations

The flowers are exuberant and even defiant in their celebration of the hot-color palette.  Associate with other plants whose performance involves orange, scarlet, deep burgundy, and ebony.  Sesbania could be the plant to nudge you to create a red garden—or at least site where pinks and blues (and even whites and grays and yellows) aren't also within view.      

Plant partners

Sesbania tripettii can be partnered on the basis of habitat, texture, and colors.  Ideally, neighboring plants will coordinate crisply along all three metrics at once.  What about, say, an aquatic plant with huge leaves in a strongly-contrasting color to the ferny light green of Sesbania foliage and the red / orange / burnt umber of its flowers? 

 

What about one of the newer ebony-leaved Colocasia hybrids, such as 'Black Coral', 'Diamond Head', or 'Kona Coffee'?  They, too, prefer to grow in saturated mud, or even shallow water.  Their elephant ears are coffee-black, with the additional shock of being shiny, almost as if oiled.  The contrast with Sesbania couldn't be greater.  Sesbania casts such light shade that, if your plant had a head-start and grew fast enough to stay a foot taller than the Colocasia, it could be its underplanting. 

 

Canna 'Pacific Beauty' can engage in an even more wide-ranging conversation with Sesbania because, in addition to its large pewter-purple leaves, it has glowing cantaloupe-colored flowers.  This aquatic canna can grow tall enough—five or six feet—to be the backdrop for Sesbania grown as annuals.  The orange flowers of 'Mango' calla lilies bring a similar dose of orange, and with plain-green foliage for those who don't crave as comprehensive a contrast as 'Pacific Beauty'.

Where to use it in your garden

Set pots into deep saucers that you top up with water, or directly in water gardens that do not connect to the native watershed.  Provide full sun and heat; locations on terraces and/or backed by south- or west-facing masonry walls would be ideal.      

Culture

Grow in full sun as an annual in climates colder than Zone 7, where neither the plant nor any seeds it produces could survive the winter.

 

Rich soil produces the quickest growth, important where the plants have only one season to perform. 


If growing in-ground, site in almost any soil that is consistently wet, even flooded.  Where native or naturalized, Sesbania favors water-side locations, but isn't picky: Roadside ditches are a popular habitat, too.

How to handle it

Seeds have a water-tight surface that prevents absorption and, hence, enables them to float long distances.  This coating also slows germination.  Penetrate the coat by nicking, or by mixing seeds with sharp gravel, putting in a can or strong jar, and shaking vigorously. 

 

Such scarified seeds germinate quickly.  Transplant seedlings when a couple of inches tall directly to containers big enough for full-sized seasonal growth; two- gallon pots are usually sufficient.  Because the seedlings want saturated soil, anyway, there's no danger of overwatering:  Set the containers in several inches of water.  (I'm growing three potted Sesbania in a ten-gallon galvanized washtub.)  After the young plants are a couple of feet tall, there will be enough Sesbania roots that the containers can be submerged without washing the soil out of them.

 

If you're overwintering potted Sesbania, bring the plants into shelter before hard frost.  Unless your greenhouse is maintained at a temperature above seventy degrees—mine is kept only at fifty—the plants' growth will likely slow or stop.  The shrubs may even shed their leaves and enter full dormancy.  Lift dormant pots out of the water and, as long as the plants are dormant, keep them only barely damp. 

 

In the new year, increasing day length and day-time solar warmth in the greenhouse heat may nudge Sesbania into active growth.  Increase water, but lead from behind: Don't resubmerge pots into water until the plant has become quite active.  Repot to encourage larger growth, or prune to control.  Set pots into exterior water gardens only after frost danger has passed.   

How to handle it: Another option—or two!

Sesbania flowers in warm weather, and only on new growth.  The woody growth retained from the prior season, then, is useful only if a larger plant is desired.  If a more compact plant is the goal, prune as you would Buddleia davidii: Back to lowest active buds in Spring.  

 

I'm going to experiment with growing Sesbania as a pollard, by pruning old growth back to the top of a short trunk each Spring, and removing shoots that arise from the trunk or the base.  Density of growth can be enhanced during the season by pinching the tips of the new shoots. 

Downsides

Sesbania tripetii is an attractive nuisance where hardy, because the foliage and especially the seeds are highly poisonous, and can be fatal when ingested by birds or livestock.  (In my experience, little or no seed is set where the plant is grown as a tender annual, possibly because the plant is being grown outside the range of its natural pollinators.)

 

The species self-seeds rampantly where hardy, often forming large thickets.  Because the tree favors locations where its seeds can drop directly into water, it can self-seed over wide areas despite the lack of dispersal by animal vectors

 

Sesbania tripetii should never be planted where hardy, and control measures have long been of interest.  Young plants that are growing in their preferred mud at the bottom of shallow water can be pulled up easily.  More mature individuals can be sprayed with herbicide or, in a nice turnabout on a species that craves aquatic habitat, be sawn off so the stump or branch stubs are beneath the surface of the water.  These submerged portions don't resprout, and if there are no portions above the water line, the tree dies.  In its native South America, the species is kept under control naturally by several herbivorous insects, and their ability to do the same in exotic colonies that have been "innoculated" with them is being explored.

Variants

There are over fifty species of Sesbania, with species native to subtropical and tropical climates world-wide.  Some are annuals or perennials, but most are shrubs or small trees.  Many are so fast-growing they can be grown as woody annuals, reaching near-adult size, as well as flowering heavily, in their first season.  They often prefer the same wet or even swampy habitat as S. tripetii.   

 

Species native to North and South America (S. drummondii, S. herbacea, and S. tripetii among them), seem more likely to be highly poisonous.  Some species native to Asia (S. bispinosa and S. grandiflora among them) are considered highly edible by both animals and humans; the leaves, buds, flowers, and pods of S. grandiflora are all popular ingredients in the cuisine of Southeast Asia. 

 

S. bispinosa is so useful it could be thought of as a "Shmoo" of shrubs, after the fictitious animal in the legendary Al Capp cartoon series, whose every part was immediately useful, and who even jumped into the frying pan voluntarily.  (Fried schmoo tasted like chicken; if the adorable creature jumped into a broiling pan instead, it tasted just like steak.)  The leaves of S. bispinosa are good animal fodder, and the seeds are good feed for birds.  A gum can be isolated from the sap, and is an effective thickener for soups.  The wood is good for fires, and the plants grow so fast they can be coppiced for firewood frequently—or even planted as a "firewood annual."  The wood can also be processed into fibers that can be used as a substitute for hemp in making rope or heavy cloth.  The roots fix nitrogen in the soil.  The flowers are edible.  The seeds can be incorporated into a poultice for treating ringworm.

 

The foliage of all Sesbania species is pinnate, and the flowers are born in short racemes .  Flower color can vary from white to yellow to rosy-pink to orange to coppery red.  Flowering when still very young is typical—usually within the first year of growth, and sometimes, as with S. tripetii, within two or three months of germination—as is a prolonged flowering season, often from mid-Spring to late Summer.   

 

S. tripetii is one of the hardier species, both because it is readily deciduous and because it resprouts from lower sections in the event of dieback.  It is hardy as far north as Virginia.  It should be an easy container specimen to overwinter, dormant and leafless and pruned way back, in an out-of-the-way corner of the heated greenhouse.  If I'm successful with S. tripetii, I'll try S. grandiflora next.  As befitting the latin name, this species' flowers are large, indeed: two to three inches long, several times the size of those of S. tripettii.  They're also pure white, which would make this species a comfortable Summer component of a pink-friendly garden.

Availability

Seeds are available on line.

Propagation

By seed.

Native habitat

Sesbania tripetii is native to Brazil, Argentina, Paraguay, and Uruguay.  It has become naturalized more widely in South America, as well as the southeastern United States and Africa.

 
 
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