growing and blooming clivia, with longwood’s alan petravich

IF YOU WANT the best houseplant ever, look no further than Clivia. With help from Alan Petravich, then of Longwood Gardens, I learned more about these longtime favorites. We spoke one recent March, just before the traditional Clivia bloom season and the annual North American Clivia Society Show,.

Decades ago, I inherited the big old Clivia plant that had inhabited the sunroom of the home I grew up in for years before that. All these eons later we still live together, Clivia and I, as we have at several locations in between, though now there are multiple plants, each a division and each monstrously bigger than the one I started with.

And then maybe 15 years ago I bought a yellow-flowered Clivia [above] at a botanical garden plant auction, and last year a young plant of a Clivia species unknown to me arrived in the mail as a gift from friends….so you get the idea. I like clivias. A lot.

Alan Petravich, who at the time of our conversation was the Longwood Research Specialist, is even more passionate and far more knowledgeable. He was at Longwood for 16 years and led various projects, including Clivia and Canna breeding, and trialing plants from around the world for future displays, plus contributing to Longwood’s Behind-the-Plants blog.

Longwood researchers at the garden in Pennsylvania, including Alan, have been working on Clivia breeding since 1976, In recent years, Longwood has hosted the annual North American Clivia Show, each year in mid-March (details at the bottom of the page).

We talked about growing Clivia to perfection, how to trigger its bloom, unusual variegated varieties, and even propagating from seed and division. Read along as you listen to the March 7, 2016 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

my clivia q&a with alan petravich

Q. Before we get to the latest breeding introductions, when we say Clivia, we are usually talking about what species of this plant?

A. Typically we’re talking about Clivia miniata. Clivia miniata is a species that has the largest flowers and they are held upright, and they’re very showy.

Q. They are indeed. Where do they come from in the first place, in nature—what regions and kinds of environments are their native habitat?  

A. Clivias come from southern Africa. They grow in the forest, and need shade. They’re not epiphytic, but they have very thick roots that are sort of like orchid roots and they kind of grow along the tops of rocks and tree stumps and things like that, but they do need a cover of organic leaf litter to live. So under the trees, with a cover of leaf litter.

Q. What are they related to? Where do they fit in, in the taxonomic order of things?

A. They are related to amaryllis, so some of the flowers do resemble amaryllis flowers if you look at them individually.

Q. Yes, different scale maybe, but yes. When I saw the press photo of the latest Longwood introduction I thought, “Uh-oh, how can I make room here for yet another Clivia?” [Laughter.] It’s a sickness, right? Plants are a problem for some of us.

A. Sometimes you get Clivia Fever; I really understand.

Q. Well maybe you can off the air later recommend a doctor for that.

A. [Laughter.] I don’t know if there is one.

Q. Tell us about the newest introduction, and then we can talk about your general directions at Longwood for breeding them.

A. The newest introduction is called ‘Longwood Chimes’ [photo at tip of page], and it’s a reddish-flowered Clivia. It actually opens with a green throat, and with color that’s called a bronze, so it has an orange petals with some green in it, so it gives a bronze-ish cast. As it ages, it changes color and becomes a darker red, almost a brick red as the flower ages, just before they fall off. It’s a really interesting plant.

Q. It looked spectacular in the photo. Now we should probably say to people who haven’t grown Clivia, that Grandma’s plant like I’ve got—or Mom and Dad’s—are general speaking a deep orange, a very vibrant orange color.

A. Yes, that’s the typical color.

Q. Did yellow occur in nature, or was that a result of breeding—the yellow-flowered ones?

A. There were some yellow-flowered ones occurring in nature. Longwood actually started breeding Clivia in 1976, and as you said, orange was the prevalent color. There were some yellows in existence, but they weren’t that superior. The flowers may have been small, or the umbel—the flower head—wasn’t spectacular, or the flowers were hidden down in the foliage.

The breeding program actually started here to produce a superior yellow-flowered Clivia.

Q. So one that held its flowers up above and the umbel was well-shaped—dense and beautiful, impactful visually?

A. Exactly.

Q. I have a pretty early yellow one, and it’s beautiful—but probably not as early as the ones you have bred since. [Laughter.]

A. You’re kind, thank you.

Q. How many introductions has Longwood made over those years?

A. This is the fourth introduction. The first two introductions were yellow. The first was called ‘Longwood Debutante,’ and she’s a beauty [photo above]. She has kind of a buttery flower, with nice overlapping petals, and slightly fragrant. Some people can smell Clivia fragrance, and others can’t. When an entire greenhouse of clivias is in bloom, I can smell them, but I can’t really get a fragrance from individual flowers often.

She was first. The second introduction was ‘Longwood Fireworks,’ and the umbel of ‘Longwood Fireworks’—the flower head—is almost a perfect ball, so it has this really nice display.

The petals actually reflex—so they’re kind of bent backwards—and it looks like the anthers are shooting out of those flowers, so it looks like fireworks are exploding in the sky.

The third release is an interesting flower shape. Typically Clivia flowers are very flat, so they’re in the same plane. We actually developed flowers that have what we call a keel—so there’s an extra ruffle in the center of the petal that adds some depth and texture to the flower. The third release was called ‘Longwood Sunrise.’

Q. And that has a “keel.” [Laughter.]

A. Exactly.

Q. I love that the whole world of plants—the botanical world—has its own language, as do all disciplines in science. So you said “umbel,” and we just said “keel.” It’s so great not to be afraid of understanding these words, because it helps you to look closer when you know what you’re looking at, and looking for.

And these words are not hard—not like some of the Latin names of things. [Laughter.]

A. It’s true. [Laughter.]

Q. I suppose the most important thing is growing them; the how-to.  I grow my old guys as houseplants; I’m a Zone 5 gardener. I guess they are hardy to Zone 9, but for most of us in the U.S. they are houseplants. I have to confess despite our very long relationship, I never indulge my plants much. They are pretty tough, but I’m probably not doing the best job I could be. Can you tell us Clivia “best practices?”

A. You’re absolutely right: They are tough houseplants. One of the things I love about them is that I don’t need to water them every week; they can go two or three weeks without water.  They will benefit from proper treatment, of course.

I would start with a well-drained media—you don’t want the Clivia to have wet roots. They resent that, especially because they need to be cool and dry when they go dormant in the winter. If they’re standing in a heavy soil with lots of water, they could produce rot. So start with a good mix; that’s the best place to start.

We use something light and airy; avoid heavy clay. A nice light potting mix would be great.

They need bright light, but they burn in direct sunlight. They can have morning light, or late-afternoon light, but they can’t have noonday sun. I start worrying about sun intensity toward the end of February. I have them growing in the greenhouse here at Longwood, and typically the snow washes all the shading off my house, so by the end of February I am a little afraid they will start to burn, so we actually put up some shade cloth.

Do not allow your Clivia to be exposed to full hot noonday sun, or they will burn quickly, and the edges will actually fry.

Q. If one carries them outside in the fair-weather months, you’re not putting them in the sun, but maybe under a deciduous tree? Indirect bright light?

A. Right. I know Clivia people are terrified of hailstorms, because hailstorms will roll through in the summer and the hail can really shred the leaves. So you should have some form of protection—like a dark corner of a patio that doesn’t get full sun.  I do some behind my garage where they get some protection from pine trees—but then you have to watch out for pine pitch coming down on them as well.

It should be clean, but somewhat protected as well.

Typically you can move them outside after danger of frost is past, and then move them back in just before the first frost of the season in the fall.

Q. I have read a lot about the triggers for getting them to bloom. And then of course reading about the show that you host at Longwood—it’s important for a competitive grower that they come into bloom on time, if you’re going to show your plant.

A. Yes, no stress involved there. [Laughter.]

Q. With my plants I’m like, “OK guys, guess what? This is our regimen and you are going to bloom when you want to according to the regimen I’m affording you.” I have no schedule, like the show. What are the triggers that make them get ready to bloom, whenever that is?

A. To trigger them to bloom, you actually need to give them a cool period, and during that cool period they should also be somewhat dry, so it mimics their natural state of dormancy in their natural environment.

Clivias need temperatures below 50 degrees for about 40 days. That is called a chilling requirement. If you don’t give this plant a chilling requirement, they will probably bloom later in the year. If my plants don’t get the proper chill, they’ll bloom in June—which is great, but I need them to bloom for the show.

So what I do is I bring the plants into the greenhouses before the frost, and grow them as chilly as I can—as many days as temperature under 50 degrees as I can [but above 35F]. During that time I also keep them dry. I may water them every two or three weeks because they do dry out somewhat. Sometimes people who do them in their own homes, where they don’t get as much light as in the greenhouse, may not water them for the entire period. But I pity mine and give them a little water.

Q. I have to say I’m a torturer. I have a back mudroom—like a mini sunroom—so it’s bright enough, though no direct sun, but cooler than the house itself. And they go in there and they seem perfectly happy. I don’t water them at all through the late fall and maybe for a couple of months. Am I torturing them? [Laughter.] [Part of one Clivia above, in Margaret’s mudroom doorway.]

A. No, you’re doing the right thing, and they probably bloom for you. They have those big thick roots and can hold onto the moisture, and as I said when they’re in that cold condition, you don’t want them to be wet, because there is more chance they will rot if they’re wet during that cold time.

I try to give them that cold period, and then I warm them up two months before the show date. The show is in the middle of March, and I actually start warming up the temperatures in the middle of January. That gives me two months to play with them and get them in bloom.

Two months after you raise the temperature to about 60 degrees, you should start seeing flower buds, and then you know you’re on the right track. I always hold my breath a little bit [laughter], hoping I see them, and then when I see those flower buds come up I can relax a little bit.

If you don’t give them this cold treatment, they’ll bloom at another time of year—like in June, as I said, or sometimes the flower stalk is not stimulated to elongate. If you don’t give it that proper chill the flower stalk just doesn’t stretch as much as it should. It may end up that the flower is really blooming down below the leaves, and you don’t even see your plants blooming, because it’s hidden.

Q. The most exciting thing is when you see that flower stalk, not open but starting to push up. It’s like, “Here it comes, here it comes.” It’s quite amazing.

A. It’s like magic; one day it’s not there and the next day you can see it.

Q. Exactly. And I have to say, obviously people I love them for their incredible flowers, and at Longwood since 1976 you’ve been breeding them for better flower color, presentation held above the foliage—all these good things. But I frankly love Clivia for their almost-shrubby stature among houseplants. They’re evergreen and almost look like a shrub if you have them in a big pot.

A. They’re very architectural, yes.

Q. Do we feed them—whether to trigger flowers or for healthy leaves?

A. When I wake them up from cold dormancy I give them clear water, and once they finish blooming I start fertilizing them. Once a week I hit them with a balanced fertilizer—at home I just use Miracle-Gro, about half-strength in my watering can.

If they are in a container for a long time—you mentioned you have some pretty massive plants at your house…[laughter]…

Q. It has become sort of a feat of engineering to move them inside and out, yes.

A. I totally understand. I would suggest top-dressing them with a slow-release fertilizer with micronutrients. If the plant is really old and has been in that same soil for so long, the micronutrients have probably leached out. If you’re fertilizing it with the Miracle-Gro, you’re giving it the major nutrients, but they might need a touch of some minor elements to flourish.  I would suggest that if they’re very old plants that haven’t been transplanted in awhile.

Q. How long do you think they can live?  It seems like forever.

A. Like you said, generations pass down Clivia. I’ve asked some experts and they don’t really know, but they last a very long time. They’re slow to mature, so that’s part of it.

Q. I have divided them; I don’t just still have the one plant from my childhood home. I have divided it various times and have many large plants. Let’s talk about division—you can take them apart not unlike a daylily, for instance, and make divisions. 

A. Especially with the older plants, yes. The leaves are called fans, and if there are multiple fans in a pot and they’re very old, you can just remove them from the pot and grab a fan with each fist and just pull them apart. There is no cutting involved; they usually just come apart. The roots come apart like fingers.

If they are younger fans, sometimes you need to cut them to divide them. If that’s the case and you need to make an incision to divide a smaller fan from a larger fan, you probably don’t want to water the repotted plant for a day or two so the cut can dry out.

Q. So it can heal?

A. Yes, so it heals, or you can get rot.

Q. After the flowers fade these charming red berry-like structures form. Am I supposed to cut the stalk off, or just enjoy the look of the berries? And this hints at propagation, as I assume I can make more plants that way, too—sexual reproduction .How does that all work?

A. You can have your choice. As soon as the flowers finish blooming, you can snap off the flower stalk and stop the berries from forming. That will actually be beneficial for next year’s bloom, because if you leave it on and it forms berries, it’s taking energy from the plant, feeding all these berries, and might be too tired next year to flower. So if you’re really concerned about flowering the next year, by all means take that flowering stalk off once it’s finished blooming.

Q. If I wanted to grow more from seed, you wrote a very comprehensive how-to article on growing Clivia from seed on the Longwood website. What’s the short version of that—when are those seed ready, and what’s the signal of when to propagate from them?

A. They will have turned colors, so when the berry—it’s called a berry—is not ripe it’s a green color. As it matures it turns color. So if you have a yellow-flowered Clivia you are going to have yellow berries [above photo], and if you have an orange-flowered Clivia you’re going to have red, purple or maybe orange berries. So when they turn a color, whether orange or yellow, you kind of squeeze the berry a little—it kind of feels like a peach that’s almost ripe, or you feel a little bit of crackle. That’s when they’re ready to be planted.

Q. Do they need heat, like a germinating mat, or a moist chamber with a dome on it or…?

A. They’re really easy to germinate. The most important thing is to plant them fresh; do not let them dry out. If they dry out, they lose viability. As soon as you harvest them from the berry—it’s fun peeling them out; you take your thumbnail and you peel off that red or yellow coat. It’s almost like pearls in there [photo above]. And they’re large seeds.

Sow them as soon as you can. You can use Tupperware, at room temperature, in bright indirect sunlight. That’s a great way to do it.

You don’t even need to bury them; you can just lay them on the soil surface. What happens is they produce this huge root, that’s very large. Even if you do plant them, that root is going to push the seed out anyway, so I just decided I wanted to plant them one time, so I wait until they produce that root and then I plant them in their own pot.

They’ll produce that big root first, and then they’ll produce a shoot. And when the shoot gets maybe an inch or two long, I take them out of the Tupperware and put them in their own little pots and grow them on from there.

Q. Your detailed article on how to grow them from seed is at this link.

Let’s talk about the show: I expect people may be selling plants, and judging—what goes on at the show?

A. A lot of Clivia enthusiasts come to the show and bring their prize plants. It’s always very exciting. Sometimes the enthusiasts are very private, and we don’t know what they have, so it’s very exciting to see the plants they bring. W only see each other once a year, so it’s a great camaraderie.

You’ll see a lot of interesting things. Some Clivia are just grown for foliage, so you’ll have little Japanese or Chinese varieties that are very tiny, or normal size, but all the leaves are in a perfect plane—this beautiful little fan. So it doesn’t matter if there are flowers or not, because that fan of leaves is so perfect.

Some of the leaves are variegated. There is a type of variegation called Light of Buddha, where there is sort of banding on the leaves, so you have this green leaf that goes into this beautiful band, and looks as if it’s lit within.

It’s just a great variety of plants, and sometimes people bring interspecific crosses that are different flower forms and different color. So it’s very exciting—and actually the North American Clivia Society has shows on both coasts. There is one at the Huntington Gardens and Library the same weekend on the West Coast:

prefer the podcast version of the show?

MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the March 7, 2016 show right here. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

(Photos except of Margaret’s mudroom and her yellow Clivia are from Longwood Gardens, used by permission.)