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


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NEW Plants to Try!

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New Gardening to Do!

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


Plant Profiles

Siberian Cow Parsnip



June is cow parsnip season, and this Siberian species is the largest of all.  At  only seven feet, my individual is a midget!  Even so, it soars above "normal" perennials at the front of its bed.




The immense heads of flowers are amusing, held as high in the air as the pie plates that were kept spinning atop bamboo poles on "The Ed Sullivan Show."  But the gigantic foliage is truly awesome.  Leaves on full-sized specimens—see "How to handle it: Another option—or two!"—can be four to six feet long, and three or four wide.  My two-footer only hints at how expansive a happy cow parsnip can be.





Here's how to grow this architectural as well as edible beauty:


Latin Name

Heracleum sosnowskyi

Common Name

Siberian Cow Parsnip, Siberian Hogweed


Apiaceae, the Carrot family.

What kind of plant is it?

Herbaceous perennial.


Zones 4 - 9


Large-scale, clumping, upright biennial or triennial.

Rate of Growth


Size in ten years

Six to eighteen feet tall, six to ten feet wide.


Big-boned, large-scale, tropical.  If your preferences are to the delicate and modest, you'll probably describe cow parsnip as coarse.

Grown for

its large, green, jagged-edged, multi-pointed, and somewhat fuzzy leaves, as big as any rhubarb's but appearing right on up the flower stems as well as from the basal clump, giving the plant a much greater overall volume than any rhubarb.  The foliage of H. sosnowskyi is noticeably more divided and ruffled than its close and more widely-known cousin, H. mantegazzianum.


its potential for size, which is extraordinary even for cow parsnips, already among the largest hardy perennials.  My H. sosnowskyi is a relative shrimp at seven feet.  In more congenial circumstances, the flowering stems can soar twice that and more.  As with all biennials, plants that sow themselves are usually more vigorous than ones you germinate and then transplant.  See "How to Handle it: Another option—or two!" for strategies to maximize growth.


the startling and large heads of white flowers, like juiced-up Queen Anne's Lace over a foot across, atop thick-as-bamboo stems that bring an architectural form to the late-Spring garden.


its rarity in cultivation, and hence the distinctive variety that it brings to expanses of more familiar horticulture.


the thick pale-colored roots that are, indeed, parsnippy.  Apparently, cows adore them, and—with cooking—humans can, too.

Flowering season

Mid-Spring: Late May into June in Rhode Island.

Color combinations

Cow parsnips of all forms have white flowers and mid-green foliage.  Color-wise, they go with just about anything. The challenge, instead, is to partner cow parsnip with plants that can handle—culturally as well as aesthetically—its immense size and meteoric life style.

Plant partners

The very largest specimens of cow parsnips are achieved by growing plants in a dedicated bed, with the same obsessive, unstinting, and gleeful mindset you would use for growing other more traditional vegetable giants, such as half-ton pumpkins or thirty-pound cabbages.  See "How to handle it: Another option—or two!" below for strategies to grow exceptionally large cow parsnips. 


Cow parsnips can also be grown in less lavish and isolated conditions—i.e., with companion plants—as long as you're content with size that, while not record-breaking, is still huge by the measure of any normal perennial.  Consider pairing cow parsnips with deeply shade-tolerant, wide-spreading, and dense groundcovers, which can tolerate the 'nip's seasonal "avalanche" of foliage, and also fill in again in late Summer, when most Heracleum species have long ago gone dormant.  Vinca?   Fast-spreading ferns, such as hay fern?  Ivy?  Variegated bishop's weed?  It's best to partner this gigantic thug only with other thugs. 

Where to use it in your garden:

Cow parsnip's eagerness to get up-and-at-'em in Spring is balanced by equal eagerness to wrap up business and go dormant by Summer.  The biennial species, such as H. sosnowski, die completely after flowering; even the perennial H. lanatum gets shabby by August.  So they are all best sited as out-of-the-way focal points, where you need to walk over to enjoy them but then don't need to look at that spot later in the season when they're through or still collapsing week by week.


Although they love rich soil and plenty of water, heracleums aren't bog or pond dwellers.  Instead, site them like you would rhubarb, in fabulous soil that also has good drainage.

How to handle it: The Basics

Hogweeds are almost alarmingly vigorous in early Spring, and their enormous foliage can completely and quickly swamp everything within reach.  In the wild, this tactic ensures better access to full sun and soil moisture; in a garden, you'll need to give these plants enough room in the first place.  The whole point of them is their uniquely large scale and size, which any kind of restraint would diminish.


As soon as they become available, scatter seeds on the surface of friable and deeply-worked soil.  Don't pat down or water in.  Cover the planting area with mesh, or row-cover fabric such as Remay, to prevent birds from eating the seeds and dispersing them into surrounding woods. Thin seedlings to a foot apart the first year, and the following Spring to one per square yard.


The first full year after germination, growth is usually limited to a basal rosette of a few large leaves.  The next year, a massive cane-like stem emerges from the center of the returning rosette.  Because the stem is hollow, it has the same enhanced rigidity of a length of pipe compared to a similar length of a solid cylinder of identical thickness and material. Despite its great height, then, a Heracleum stem is soundly self-supporting.


A massive branched umbel of flowers tops the flowering stem.  The center "galaxy" of flowers can be well over a foot across, with merely foot-wide outrigger galaxies at the tips of widely-radiating stems.  After flowering has peaked, dead-head without fail to control self-seeding, letting only a few seeds fall to the ground to carry on the colony.  Don't wait until the entire plant has died before attempting to control self-seeding: Dispersal is nearly complete by that time.  

How to handle it; Another option—or two!

Because astounding size is Siberian cow parsnip's claim to fame, do what you can to enhance it.  Getting the young plants off to a good start is as important as what happens to them after they're launched. 


Self-sown plants are usually more vigorous than any you germinate and then transplant into place, no matter how carefully.  To stack the deck towards titanic growth, prepare a lavish planting area just for your Heracleum, by creating a mound a yard across that is, if possible, stuffed with your best compost and dug to maniacal depth.  Locate it where there's no chance of foot traffic, so that its fluffy internal structure and, most important, deeply fissured and friable surface, both of which have resulted from your obsessive enriching and cultivating, remain undisturbed.


Next, wait for the seed-head of an established plant to mature, which will take place in late June or early July.  It will ripen steadily, with the stems of the immense umbel turning brown and the seeds beginning to dangle seductively.  After you've seen that seeds have started to fall on their own, hold a piece of stiff white paper or cardboard under the umbel—the light color will help seeds that land on it show up—and tap the main stem of the umbel with either a protectively-gloved forefinger, or the handle of your trowel.  Be gentle: You want to dislodge fresh seeds and have them fall down onto your cardboard, not jostle the head so strongly that seeds are boomeranged all over the garden.


Tilt the cardboard or crease it, so the seeds slide into a cup, and then, cup in hand, return to your planting mound as quickly as possible.  In imitation of the seeds' natural fall from the height of the umbel—remember, they could be tumbling to the ground from ten feet in the air or more—hold the cup at shoulder height and gently tilt and "shimmy" it so the seeds trickle out.  Start dispensing seeds slowly, and adjust your position so that the seeds actually make it onto your planting mound, not into the surrounding area.  Cover the planting area with mesh, or row-cover fabric such as Remay, to prevent birds from eating the seeds and dispersing them into surrounding woods.


Now the most important step:  Walk away.  Don't pat the seeds into the soil, and don't water helpfully.  Let Nature and the seeds synergize in their own time.  Normally, germination will begin in a few weeks.


By September, a number of small and round-leaved plants will be in evidence, and you can remove the row-cover fabric.  Gently thin out the seedlings, leaving only the most vigorous three or four.  Given that Siberian cow parsnip is native to habitats with severe Winters, protective mulching isn't necessary.


The next Spring, confirm the seedlings' return to growth.  Cow parsnip awakes fairly early in the season, so don't dally in your late-Winter monitoring.  Thin all but the most vigorous one of the seedlings.  Water if the weather is unrelentingly dry, but remember that they don't call these plants "parsnips" for nothing.  Their thick roots should be able to penetrate deeply to reach more water, especially because you've prepared the planting bed so enthusiastically.  


It's fine to fertilize with, say, fish emulsion or manure "tea."  (For the latter, steep a five-pound burlap bag of horse manure in a thirty-gallon galvanized can of water).  Avoid man-made fertilizers, which only feed the plant itself, not the soil that it's growing in.


It's likely that the plant will concentrate on basal growth for a full year, and the massive roots that support it.  Your efforts at high-altitude flowering stems will be rewarded the following season. 


Unless your Spring is late to arrive where you're gardening, by mid-July of any Heracleum species' flowering year, it's about time to harvest fresh seed and begin the cycle again.  Carefully bag up the seed heads you don't need, and dispose of them in your trash, not in your compost pile.  You can compost the leaves and stems.  Dig up the mother-plant's parsnippy roots, lavish a fresh round of compost onto the mound, dig it in thoroughly, and sprinkle your fresh seeds from on high, onto the ready-for-a-new-crop planting mound. 


All Heracleum species are champs at self-seeding.  Grow them responsibly, dead-heading as soon as the flowers have passed.  For the biennial species, such as H. sosnowskyi, leave only a small flower portion to mature to seeds, and be alert for out-of-bounds volunteers.


There are several dozen other species of cow parsnip, but the species' immense size limits their use in gardens that are compact.  Gardeners for whom the massive foliage doesn't seems coarse will avoid them, too.  And then, there's the matter of the sap.  Like Heracleum sosnowskyi, H. mantegazzianum has bristling canes and foliage that are laden, who knows why, with a chemical that, even from casual contact, can make human skin extraordinarily sun-sensitive.  Cut stems can drip sap, or worse, splash it into unprotected eyes.  Unlike poison ivy, there's great variance in a given individual's sensitivity.  Severe and even disfiguring rashes can result if the gardener doesn't wear protective long sleeves and pants, plus safety glasses.  H. mantegazzianum is now illegal to sell, but it is not illegal to grow, nor is it illegal to pass along seeds to gardening friends who are committed to growing the plant responsibly.  So far in North America, H. sosnowskyi is seeding below the radar, so to speak.


Heracleum lanatum is perennial, and not allergenic.  For a cow parsnip, it's modestly-sized at only five or six feet tall and wide.




By seed.

Native habitat

Heracleum sosnowskyi is native to eastern Siberia, where cold Winters and cool Summers favor its Jurassic Park aspirations.

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