Cactus or Euphorbia?


If you grow cactus and other succulents, you probably have a few euphorbias mixed in with the cacti. Source:, montage:

In the world of succulents, that is, plants that store water in thickened stems or leaves in order to better cope with arid conditions, two different families are often mistaken one for the other: cacti (Cactaceae) and euphorbias (Euphorbiaceae, genus Euphorbia). In fact, many people simply call all succulent euphorbias “cacti,” not realizing there is a difference.

Both cacti and euphorbias tend to be stem succulents, that is, they store moisture in swollen stems, both tend to very spiny and both include a variety of species of all different shapes. They are so similar in many aspects that confusion is understandable, yet they are no more closely related to each other than dogs are to cats.

Dogs and cats are both mammals, are covered in hair, have tails and pointy teeth and are carnivores, yet few people would confuse a dog with a cat. If you’re a gardener, you really should learn to tell a euphorbia from a cactus. Once you know the difference, you’ll never confuse them again.

Convergent Evolution

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As a result of convergent evolution, many cacti and euphorbias have evolved to resemble one another. Source: &

The similar appearance of cacti to euphorbias is an example of convergent evolution: the two different families evolved under similar conditions—under extreme aridity—and adopted similar survival tactics, resulting a lot of similarities. Even so, they also have their differences.

Telling the Two Apart

Here are a few tips on telling the euphorbias from cacti. You may well find you’re growing both of them without knowing it!

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A cushiony areole, with or without spines, is a sure sign of a true cactus. Source:

  1. Cacti have areoles. These are cushiony, fuzzy dots from which spines, stems and flowers grow. They can be white or yellow, but are present on all cacti. No other plant has areoles. So, if you look closely at any cactus-like plant and see no areoles, as will be the case with euphorbias, that plant is definitely not a cactus! This is, hands down, the easiest way of telling the two apart. Once you know this, you’ll never confuse a cactus with any other plant again!

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    Euphorbia thorns, usually single or paired, are part of the stem and hard to remove. Cactus spines often form a circle and are easily broken off. Source: Hernán Conejeros, & Elton Roberts,

  2. Euphorbias usually bear single or paired thorns (modified stems), if indeed they have thorns. They’re usually thick and are clearly part of the stem: you can’t break them off without wounding the plant. Cactus have spines (modified leaves) rather than thorns. They often form a circle, although not always, and there may also be longer spines in the circle’s center. However, no matter how they are grouped together, cactus spines always arise from those cushiony areoles mentioned above. They can be snapped off very readily and indeed, some are designed to break off and penetrate the skin of animals to dissuade them from chomping on the cactus. Note that there are both thornless euphorbias and spineless cacti, so the absence or presence of prickles is not necessarily a factor in distinguishing between the two.

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    Euphorbias produce milky white sap, cacti rarely do. Source:Norman E. Rees, USDA ARS

  3. Euphorbias produce milky sap if you wound them. This is a sticky latex, often toxic or irritating to the skin, and almost always white (there is just one species with yellow sap, E. adbelkuri). Most cacti have clear sap, rarely irritating to skin, although there are a very few cacti with white sap, including a few Mammillaria.

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    Cactus flowers are highly varied and usually colorful. The true flower of the euphorbia above is the center and is unremarkable; it is only made attractive by the bracts that surround it. Source: Florence Rogers, Nevada Public Radio &

  4. Cactus flowers are usually showy and colorful, with typical flower parts, including petals and many stamens. Take a look at how they are placed on the plant: they always grow from a cushiony areole. Euphorbia flowers tend to be small and yellow, have no petals and are usually quite insignificant, although in some species, such as the crown of thorns (E. milii), they are surrounded by modified leaves called bracts that can be quite colorful. They never grow from areoles.
*Be aware that unscrupulous cactus growers often stick fake flowers on cactus with glue guns. If the flower on a cactus does not grow from an areole and has a glob of glue underneath, you’ve been had!
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Many euphorbias, like this Euphorbia trigona, have leaves. Few cactus do. Source:

  1. Cacti are almost always leafless, at least as adults (all bear two cotyledons at germination). There are only a few exceptions (Pereskia, which actually don’t look like cactus at all, and a few Opuntia, for example). On the other hand, many euphorbias with succulent stems nevertheless bear leaves.
  2. Cacti evolved in the New World and are found in North, South and Central America as well as in the Caribbean. (There is only one species, Rhipsalis baccifera, that is native to the Old World.) Succulent euphorbias evolved in the Old World, mostly Africa, Madagascar and drier areas of Asia. In the wild, both are still mostly found in their native lands, although some cacti, notably in the genus Opuntia, have escaped from culture to become weeds in other parts of the world.

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    All these euphorbias are in the single genus Euphorbia, but the cactus shown are in various genera, including Mammillaria, Trichocereus, Astrophytum, Opuntia and Cereus. Source: lonelyplant_ph, &

  3. Euphorbia is just one genus in the family Euphorbiaceae. They are often called spurges. There are more than 2,000 species of Euphorbia, including such popular houseplants as mottled spurge (Euphorbia lactea), pencil tree (E. tirucalli) and crown of thorns (E. milii). Cacti are a family, the Cactaceae. The family also contains about 2,000 species, but is divided into about 175 genera, including Opuntia, Echinocactus, Mammillaria and Cereus.

There you go! It isn’t all that hard to tell euphorbias from cacti. Just the lack of an areole on euphorbias should be such an obvious difference that you’ll never confuse the two again!


The ‘Red Delicious’ Falls From Favor


‘Red Delicious’ apples, famous for their red fruits and lengthened shape ending in five points. Source:

The ‘Red Delicious’ apple was for more than 50 years the best-selling apple in the United States, but its reign is now officially over. “Only” 51.7 million Red Delicious apples will be sold in the US in 2018, a decrease of 10.7% over last year, while ‘Gala’ apple sales will exceed 52.4 million, an increase of 5.9%.

Already, Americans have been buying fewer ‘Red Delicious’ for over a decade now and the bulk of this year’s production will now be sold abroad. On the other hand, growers just can’t produce enough of the rising star in the apple world, the ‘Gala’. Many ‘Gala’ apples are still imported annually to meet the need.

Orchards are rapidly removing the ‘Red Delicious’ trees, replacing them with other varieties. Don’t expect to see ‘Red Delicious’ apples in the average supermarket much longer.

The basic problem is that ‘Red Delicious’ is not so delicious. It’s a very attractive apple, perfectly red, and its skin, thick and leathery, almost waxy, makes it an excellent apple for transportation and storage. But the taste? Not so extraordinary … at least, not in the form offered on the market.

History of a Not-So-Delicious Apple

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This is the original ‘Hawkeye’ that gave birth to the much redder ‘Red Delicious’ of today. Source:

The ‘Red Delicious’ type of apple was first found in Jesse Hiatt’s orchard in Peru, Iowa, in about 1870. He called it ‘Hawkeye’. He later sold the rights to Stark Nurseries who changed the name to ‘Stark Delicious’ and began propagating it. When the same nursery released a cultivar called ‘Golden Delicious’ (in fact, not a close relative of ‘Stark Delicious’, but a tree with a distinctly different genetic background) and realized this was confusing consumers, they again changed the name and began calling it ‘Red Delicious’ in 1914. Even so, the newly renamed ‘Red Delicious’ was not yet the perfectly red apple we know today, but rather red lightly marbled yellow, as per the original ‘Hawkeye’.

In 1923, New Jersey orchardist reported a bizarre situation. A branch on one of his ‘Red Delicious’ apples produced apples that turned red very early, before the fruit was fully ripe, while the other apples on the tree were still green. And the fruit was perfectly red, without the yellow marbling of the original. A representative of Stark Brothers Nursery paid $6,000 (a fortune at the time) for the branch bearing the mutation (for that’s what it was) and the nursery began to propagate the new ‘Red Delicious’ on a massive scale, convinced of its potential.


Today’s ‘Red Delicious’ can be any one of dozens of sports of the original. Source:

Actually, the ‘Red Delicious’ apples in stores aren’t even true ‘Red Delicious’ apples anymore, but “sports” (mutations). No fewer than 42 sports of ‘Red Delicious’ have been patented in the US alone, including ‘Starkrimson’, ‘Redspur’, ‘Early Red One’, ‘Super Clone’ and ‘Red Chief’. All are simply sold under the name ‘Red Delicious’.

Less than twenty years after the new all-red ‘Red Delicious’ was launched, that is, by 1940, it had become the most popular apple in the United States.

Why? Not because consumers liked its taste, although it was eye-catchingly red, but because it was easy to produce, ship and maintain on store shelves. You see, it was possible to harvest the fruit when it was immature, but nevertheless completely red on the outside. Immature fruits, with their thicker skin, travel better than ripe fruits and are not as subject to bruising. Also, their shelf life is enormously prolonged: harvested at just the right stage, ‘Red Delicious’ apples still look great 9 months after the harvest, even 12 months when stored in a controlled atmosphere, a boon for growers!

On the other hand, although immature apples do sweeten somewhat after harvest, they are never as tasty as mature apples: they’re not as sweet, their skin is bitter and their texture becomes crumbly.

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Today’s supermarket ‘Red Delicious’ isn’t so delicious. Many people stop eating it after the first bite. Source:

A fully ripe ‘Red Delicious’ harvested fresh from a tree is indeed delicious … but the supermarket ‘Red Delicious’, red outside, but “green” (immature) inside, is just barely palatable. Yet, for a long time it was widely available and inexpensive. Apple historian Tom Burford calls the ‘Red Delicious’ “the largest compost-maker in the country,” because consumers bought them, but then didn’t eat them: one third ended up in the trash. Typically, Mom would drop one in each lunch bag, but the kids would throw them away at school.

But ‘Red Delicious’ sales have been in decline now since the early 1990s. That’s when consumers began to show their willingness to pay more for better-tasting imported apples (including ‘Gala’ and ‘Fuji’). Soon American orchards were replacing the bland ‘Red Delicious’ with tastier varieties to win back their market. Now produced locally, ‘Gala’, ‘Fuji’, ‘Granny Smith’ and ‘Honeycrisp’ are presently, with ‘Red Delicious’, the five best-selling apples in the US, but if the trend continues—and it likely will—‘Red Delicious’ will soon drop off the list of popular apples entirely.

Elsewhere in the World

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No doubt about it, the ‘Gala’, along with is redder sport ‘Royal Gala’, is the rising star in the apple world. Source:

In Great Britain, ‘Red Delicious’ has never been popular, but the old favorite, ‘Cox’, has been replaced by the new favorite, ‘Gala’ (in the form of ‘Royal Gala’, a darker skinned sport of ‘Gala’). Other top sellers are ‘Braeburn’ (new) and ‘Russet’ (an old favorite).

‘Red Delicious’ is still commonly sold in Canada, but is rarely grown there and is usually imported from the United States. Canadians have always preferred the ‘Macintosh’ to ‘Red Delicious’ anyway, but the ‘Gala’ is now close behind the ‘Macintosh’ and even dominates in British Columbia while the ‘Cortland’ is popular everywhere and the ‘Honeycrisp’ is very trendy.

Australians like ‘Pink Lady’ and ‘Granny Smith’ (the latter developed there), but ‘Gala’ (‘Royal Gala’) is gaining fast.

In South Africa, the top three are ‘Granny Smith’, ‘Golden Delicious’ and ‘Royal Gala’.

Farewell, ‘Red Delicious’ … but with some 7,000 varieties of apple to choose from, I don’t think we’ll have a hard time finding a replacement!

Hug Your Houseplant, It’s National Indoor Plant Week!


Every year, the third week of September, is held the National Indoor Plant Week. In 2018, that’s from September 17 to 23. The event was established in 2007 to promote and increase public awareness of the importance of live plants in interior spaces. And I’m all for it. As an enthusiastic houseplant aficionado since my childhood (I wrote my first article about houseplants when I was 14!), houseplants are such a integral part of my life that I can’t imagine living without them.

Here’s an explanation from the people at

What is National Indoor Plant Week? It’s a Celebration!!!

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National Indoor Plant Week was established to increase public awareness of the importance of indoor plants and their many attributes. Only some of which include cleaning the air we breathe … we like to say, “The oxygen doesn’t arrive until the plants arrive.” Statistics have proven that indoor plants increase morale in the workplace and homes. The plant is such a miraculous living thing.

Real life office studies have been conducted to measure the direct relationship between clinical health, complaints and plant installations. Recorded health improvements in offices where interior plants were added were significant. Results show a large reduction among employees in the areas of fatigue, headache, coughs and their overall well-being rose dramatically.

Further, numerous studies have shown that plants have a positive psychological impact on people. According to a recent study, employees exposed to interior plant settings demonstrated better attitudes, positive emotions such as happiness, friendliness and assertiveness.

It’s a Celebration … So What Can You Do?

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National Indoor Plant Week celebration in Indianapolis. Source:

Industry professionals (interiorscapers, greenhouses, florists, etc.) can host a plant giveaway: they do that annually in various US cities (7,000 houseplants will be given away in Chicago alone this year!). Can you imagine the enthusiasm about houseplants that creates?

Individual gardeners can buy a new houseplant … or give one to a friend or neighbor.


Give your houseplants a bit of TLC. Source:

Or give their current houseplants a bit of TLC. How about a nice shower to wash off dust and grime? Or repotting that plant you know needs it? And certainly, bring any that are outdoors for the summer back inside if you live in the Northern Hemisphere (yes, it’s that time of the year).

I don’t care how many houseplants you already have, growing plants is so good for us in so many ways that you really need more.

How about this for a logo, people? “You deserve a plant today!”

Fall: A Sad Season for Climbing Houseplants


My pink cissus (Cissus adenopoda, now Cyphostemma adenopoda) attempting a takeover of a white spruce. Source:

September is the time of year for me to bring my houseplants back indoors … and the ones the most reluctant to come in are the climbing plants.

I hang their baskets outside for the summer from the branches of the various trees on my property … and they love it! After long months dangling from their pots with nowhere to go but down, they finally get to do what they really want and reach for the sky. They quickly cling to nearby branches and try to hoist themselves up.

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Propellor plant (Dischidia albida) massively invading my crabapple. Source:

Some have tendrils or stems that wrap around branches, others literally cling to the bark of trees with aerial roots or suckers. They’re doing what comes naturally and it’s easy to see they’re having the time of their lives.

Then comes fall and the return to domestic life indoors. I don’t even bother trying to untangle them from their host: I know from experience that simply breaks stems and leaves, leaving them worse off. Instead, I just cut off the clinging growth and bring them back indoors, shorn and chastened.

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My variegated sweetheart hoya (Hoya kerrii ‘Variegata’) put out a 7-foot (2 m) stem this summer. Indoors, it rarely grows more than 6 inches (15 cm) a year! Source:

Which plants do this? Mostly the faster-growing ones, like cissuses (Cissus adenophylla and C. amazonica are two I grow) and mandevillas (Mandevilla cvs), but even the apparently slow-growing hoyas (Hoya kerrii) and dischidias (Dischidia albida) take off at a rapid pace outdoors and need to be chopped back.

The aroids, like the various cultivars of heartleaf philodendron (Philodendron hederaceum) and pothos (Epipremnum spp.), though, always seem slower on the uptake and fail to profit from their summer host trees, just dangling downwards. I still have to trim them back, though, as their stems have gotten overly long and I don’t want plants creeping all over my floor indoors.

It’s a bit like tough love for vining houseplants. I know they hate being pruned, but they’re tropical plants and simply can’t remain outdoors permanently, not in my cold winter climate. So, snip, snip and in they come. Then they can spend the winter dreaming about being back outdoors again next summer!

The Shoo-Fly Plant: The Most Beautiful Annual You Never Planted


Jacinthe Emond and her mystery plant. Source: Jacinthe Emond

Question: Can you identify this beautiful plant? It appeared in my flower garden all on its own: I never planted it.

Jacinthe Emond

Answer: Yes, it’s a shoofly plant, also called apple of Peru (Nicandra physalodes). It’s rather a forgotten beauty, once a well-known garden annual, but one that seems to have fallen from favor. Certainly, I never see it in garden centers anymore. However, it has a rather weedy habit (although it’s easy enough to pull out) and seeds are readily carried from one spot to another by birds. In that way, it has “liberated” itself from human control and grows spontaneously as an introduced plant in fields and gardens pretty much all over the world.

Is it a weed? Sometimes! But it’s usual habit of appearing here and there rather than dominating the landscape means it’s rarely a huge problem.

The exact origin of the shoofly plant is, curiously enough, not fully known, but it is believed to be native to the Andean Cordillera in South America, possibly Peru. It’s obviously well-established as an introduced plant in North America and Europe, as I regularly receive letters and photos from readers wondering what it is.


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Flower of the shoofly plant. Source: Boronian, Wikimedia Commons

Although it may be hard to believe that such a huge plant (it ranges from 3 to 8 feet [90 cm to 250 cm] high with leaves sometimes greater than 1 foot [30 cm] in length) is an annual, it does indeed start life over again each spring from a seed. It produces lavender purple cup-shaped flowers from June or July to September or October. The leaves are dark green with a deeply toothed margin. The musky odor of the flower is said to repel whiteflies and sometimes other insects, hence the name shoofly plant, but the reputation is certainly overstated, as I’ve seen colonies of whiteflies apparently thriving underneath a shoofly plant leaf.

After flowering, an inflated green to purple calyx forms, one that can be dried and used in floral arrangements. The calyx is similar to that of the Chinese lantern, Physalis alkekengi, and the ground cherry, P. pruinosa, two plants in the related genus Physalis. All three plants are in the Solanaceae family, but the shoofly plant has its a genus all to itself: Nicandra, named for the Greek poet Nicander of Colophone, who wrote poems about—oddly enough!—poisonous plants.

He would have loved his namesake, as, unlike the edible ground cherry, the fruit of the shoofly plant is poisonous, as are its leaves. Despite this toxicity, the seeds and leaves are consumed in some parts of the world and it also has medicinal uses. I suggest not consuming any part of it unless you know what you’re doing!

Note that shoofly pie is made with molasses and not from the shoofly plant!

How to Grow Your Own Shoofly Plant


Shoofly calyx. The purple coloration of this one indicates it’s probably the cultivar ‘Violacea’. Source:

The shoofly plant doesn’t always appear spontaneously just when and where you want it, but that’s all right, as its seeds are fairly widely available, notably in catalogs offering heritage flower seeds.

Oddly enough, the best time to sow shoofly plants is in the fall, because the seeds germinate best after a treatment at low temperatures and really love a winter outdoors. If not, try sowing it outdoors in early spring, when the soil is still cool. For an extra-large plant, start the seeds indoors inside 4–6 weeks before the last frost date. Sow them in peat pots so the fragile root system can be planted into the garden intact.

Sow without covering the seeds, as they need light to germinate. Grow the plant in a sunny or, at very least, partially shaded location in well-drained soil of just about any quality. Even very poor soils are fine. It looks great in a pot too … a very large pot!


A well-variegated branche of the cultivar ‘Splash of Cream’. Source:

The cultivar ‘Violacea’, with darker flowers and purple-tinged calyxes, is often seen not only in catalogs, but even appears spontaneously, as in many areas, that’s the variety that escaped from culture. The cultivar ‘Splash of Cream’, also offered, has yellow-dotted variegated foliage. I find its coloration very irregular, with most branches showing little to no color.


Here are some of the catalogs that offer shoofly plant seeds:

Salt Springs Seed
Chiltern Seeds
Solana Seeds
Plant World Seeds
J.L. Hudson, Seedman

The shoofly plant: an oldie but goodie, certainly worth a 21st-century revival!

Some Houseplants Like Fall Outdoors


Most cactus love cool fall temperatures, but do bring in most other succulents before nights become cold. Source: &

It’s usually important to bring houseplants that spent the summer outdoors back inside fairly early in the season, even as early as the beginning of September in many climates. That’s because the vast majority of houseplants are of tropical origin and don’t appreciate the gradual cooling that comes with fall. They prefer to be brought back indoors before fall nights start to cool off.

Cool temperatures can set them back considerably. Even nights below 60˚ F (15˚ C), which doesn’t seem that cold, can cause negative reactions in many tropical plants, especially if the cold nights are repeated and soil temperatures start to drop. Growth stops, no new flowers are produced, leaves yellow and fall off … it’s just not a good thing.

Some Like It Cool

But there are exceptions to every rule.


Clivias are among those “houseplants” that actually like cool fall temperatures. Source:

There is a small minority of houseplants that are not tropical plants, but of subtropical origin. In other words, in their native environment they experience cool to very cool temperatures part of the year, yet without having to tolerate frost. These plants, unlike most other houseplants, prefer to spend the autumn outside and most will readily tolerate temperatures as low as 33˚ F (1˚ C). Therefore, bring them in only when frost is announced. In fact, if there is an early frost, it’s sometimes best to bring them in overnight, then to put them back outdoors for yet a few more weeks, until frosty nights truly become the norm.

Even when you do bring these plants indoors, trying keeping them in a cool place, with nights below 60˚ F (15˚ C) during the winter, if you can. They’ll really appreciate it!

Naming Names


Cool fall temperatures help indoor azalea (Rhododendron simsii) set buds. Source:

In this category you’ll find such plants as indoor azalea (Rhododendron simsii), some orchids (including Cymbidium), Christmas cactus (Schlumbergera spp.), most other cacti, clivias (Clivia spp.) and lily of the Nile (Agapanthus spp.). Leaving these plants outdoors for a few extra weeks even tends to encourage better flowering when they do come back indoors.

Of course, you won’t want to bring insects back in with the plants you bring back inside. To learn how to control them, read Bring Your Houseplants Indoors Without the Bugs.

Red Tulips for Parkinson’s


The red tulip is the worldwide symbol of Parkinson’s disease. Source:

Did you know that the red tulip is the international symbol of Parkinson’s disease? This devastating disease of the nervous system affects about 7 to 10 million people around the world, including nearly 1 million in the US, 100,000 in Canada and Australia and 145,000 in the United Kingdom, and the numbers are rising. Experts predict that the number of people with Parkinson’s disease will double by 2042.

It was on April 11, 2005 that the red tulip was launched as the international symbol of Parkinson’s disease during the 9th World Parkinson’s Disease Day Conference in Luxembourg. The red tulip, which rises from the bare earth to bloom gloriously each spring, was chosen as a symbol of hope for Parkinson’s sufferers.

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Triumph tulip ‘Doctor James Parkinson’. Source: mijikam,

There is actually a tulip named ‘Doctor James Parkinson’. It’s a red Triumph tulip with a white margin named for the English doctor who first described the disease in 1817 and was launched by 1981 its hybridizer, J.W.S. Van der Wereld, himself suffering from Parkinson’s disease. However, the award-winning ‘Doctor James Parkinson’ tulip is rarely available and, at any rate, any red tulip will do as the symbol of the disease. There is no need to plant a specific variety of red tulip.

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The Jean-Paul L’Allier Garden in Quebec City with its thousands of red tulips. Source: Parkinson région Québec Chaudière-Appalaches

You can plant red tulips to support a friend or relative who suffers from the disease, to honor someone who has died of the side effects of the illness or simply to show moral support to people suffering from the disease. In some regions, it’s now common to see red tulips grown in front of hospitals and hospices that care for Parkinson’s patients. If that’s not the case where you live, that’s perhaps a tradition it would be well worth starting! Our local Parkinson’s Society (Parkinson Région Québec Chaudière-Appalaches) began such a campaign in 2014 and this year we’ll be planting bulbs at seven sites in the Quebec City region during our annual Tulip Bulb Planting Bee in October.

Planting red tulips as a sign of compassion for the illness is a great idea, but the various Parkinson Societies of the world need more than floral support. Be generous, and when your tulips come into bloom, perhaps in April, Parkinson’s Disease Awareness Month, consider making a donation to your local Parkinson Society.

Show your support for Parkinson Society by filling your flower beds this autumn with beautiful red tulips … and make sure everyone knows why!