According to a gardening manual from Jefferson’s time, April is the month to graft fruit trees. So in this episode, we cut into the practice of grafting and explain it's critical to the fruit you eat every day. We also look at Jefferson's favorite nurseries along with the historic and modern nurseries at Monticello, and highlight the upcoming Center for Historic Plants Open Houses in April and May. Oh, there's pomegranates, too.

Featuring Peggy Cornett, Curator of Plants; Michael Tricomi, Manager and Curator of Historic Gardens; Debbie Donley, Flower Gardener; and Robert Dowell, Senior Nursery Associate at the Thomas Jefferson Center Historic Plants.

Michael Tricomi: : It's April at Monticello, which means lots of things are in bloom. It’s peak tulip time. Apple, pear, and peach trees are covered with delicate pink and white flowers. And we’ve even got sea kale blooming in the vegetable garden.

According to a gardening manual from Jefferson’s time, April is the month to graft fruit trees. So today, we’re going to talk about grafting -- along with historic nurseries, pomegranates and more.


Michael Tricomi: : This is “A Rich Spot of Earth,” a podcast about gardening and the natural world. I’m Michael Tricomi, Manager and Curator of Historic Gardens at Monticello, Thomas Jefferson’s home in Albemarle County, Virginia.

Historic Nurseries

Michael Tricomi: : The nursery is the heart and soul of the garden. It’s where we propagate and nurture plants before releasing them into the less protected world of the garden.

In Jefferson’s time, there were several well-established commercial nurseries. I talked with our Curator of Plants, Peggy Cornett, about a few of his favorites, beginning with the William Prince Nursery, established on Long Island in the 1730s.

Prince Nursery

Peggy Cornett: The Prince Nursery was really well known in New York. Jefferson and Madison visited this during this travel vacation they took together in the spring of 1791. A lot of fruit trees as well as native trees and shrubs were purchased during their visit. And when Jefferson returned to Monticello, he expanded this order to include roses. So that's when he ordered 10 different varieties of roses from the Prince Nursery and we have the invoices and they were shipped in the fall.

Michael Tricomi: : Jefferson placed a huge order at the nursery. It included 60 sugar maple trees. He had a plan to tap maple syrup to reduce his need for sugar. Unfortunately, he eventually discovered that Virginia was a little too warm for maple syrup production.

He also ordered a variety of fruit and nut trees, including Brignole plums, apricots, Red and Yellow Roman nectarines, Green Nutmeg peaches, Yellow October and Lemon Clingstone peaches, Beurre Gris d'Hiver pears, Spitzenberg apples, Madeira walnuts, and filberts or hazelnuts.

When Jefferson and Madison visited the Prince Nursery, Jefferson was serving as Secretary of State under George Washington and was embroiled in a slew of political disputes. His adversaries, including Alexander Hamilton, suspected that this trip north involved some sort of secret political agenda. But apparently it really was just a vacation. Besides visiting the nursery, Jefferson and Madison went fishing and walked historic battlefields.

Thomas Main Nursery

Peggy Cornett: Another nursery Jefferson was very fond of was the Thomas Main Nursery, which was in Washington DC. And from our last episode, when we were talking about the trees and shrubs that were in clumps, a lot of those came from the Thomas Main Nursery and were brought to Monticello by the enslaved gardener David Hern.

And Margaret Bayard Smith, who was a friend of Jefferson's when he was president, she gave a wonderful account of Jefferson's excursions to go to this nursery. And she said, "there were two nurseries that Jefferson took particular delight in partly on account of their romantic and picturesque location and the beautiful rides that led to them, but chiefly because he discovered in their proprietors an uncommon degree of scientific information, united with an enthusiastic love of their occupation. Mr. Main"-- Thomas Main-- "was a shrewd, intelligent, warmhearted Scotsman. Rough as he was in manner and appearance, he could not be known without being personally liked. And rare fruits and flowers were his pride and delight. This similar similarity of taste made Mr. Jefferson find peculiar pleasure in furnishing him with foreign plants and seeds and in visiting his plantations on the high banks of the Potomac."

So, in other words, it was a real experience for Jefferson to visit these nurseries to talk to plantsmen who enjoyed growing and experimenting and maintaining a big collection of plants. And so it was just a great way for him to associate with like-minded people.

Bernard McMahon

Michael Tricomi: : For Jefferson, the most important of these like-minded plant enthusiasts was Bernard McMahon. McMahon owned a nursery in Philadelphia and served almost as Jefferson’s gardening mentor.

Peggy Cornett: He was from Ireland. And I think he would, it's amazing that he published this book, he hadn't lived in the. In this country that long. I think he really was a plantsman and I think he tried to encourage Jefferson a lot of times to try things, even though Jefferson kept resisting. He would send him these really unusual bulbs and Jefferson wasn't sure he had the time or energy or space to grow them because they were greenhouse plants. They were plants that needed a lot of special care, but then Jefferson would turn around and order a bunch more from him. Jefferson was insatiable about plants anyway.

But McMahon, we credit him with sending Jefferson some very unusual plants too. McMahon was the source of the sweet-scented four o'clock, which is quite unusual. We don't know how McMahon got seed of that because it's a native to the Southern US and down into Mexico.

Michael Tricomi: : The Latin name for sweet-scented four o'clock is Mirabilis longiflora. Its fragrant white blossoms unfurl at dusk. We continue to grow them today at Monticello.

Peggy Cornett: And then Jefferson was sending Bernard McMahon plants that were brought to Jefferson from the Lewis and Clark expedition. Jefferson was president and he just didn't have time or the resources to grow these things. And so he really counted on McMahon, especially.

So, McMahon was growing these plants and even giving them English names after he was successful in propagating them. The Snowberry Bush was from Oregon. It's a, maybe, four- or five-foot shrub at its maximum. It's a deciduous shrub. And it has very small flowers and the fruit is a white berry in clusters, and they're very beautiful, pure snow-white color. If you can grow a good one, I think it's really nice, it's a little bit of a challenge here.

And also, he was propagating the Oregon Grape Holly, which is Mahonia, but it's not the Chinese Mahonia. This is a smaller leaf. It does have bright yellow clusters of flowers right now, actually, it's blooming in the spring. And then it's followed by a bluish berry and it's an evergreen.

They both became very popular, especially in England, where they do quite well in that climate. The climate of Oregon, it's actually more conducive to the same climate in England than it is here on the east coast of the United States.

There was a big interest in American plants at that time. McMahon was propagating these plants and selling them.  In fact the prince Nursery, during the Revolutionary War, apparently, the British soldiers didn't want to do any damage to that nursery because after the war, they were wanting to send plants back to Europe. So they didn't sack the nursery.

The American Gardener's Calendar

Michael Tricomi: : Bernard McMahon published an important reference book, called The American Gardener's Calendar. It lays out the essential garden activities for each month of the year.

Peggy Cornett: Jefferson received a copy of this book in 1806, the first publication of the book. McMahon was proudly sharing it with the president of the United States. And Jefferson really was pleased to get it. You can find notes in Jefferson’s own hand that were taken directly out of McMahon’s book. Jefferson’s leaving notes for his overseer or for his granddaughters how to plant certain things. And when you reference it back to McMahon’s book, it’s almost word for word. 

And his appendix is really a great resource for us, as far as helping us to expand the plants that we grow in the garden today. We're always finding new plants that we could add to our collection that were documented in The American Gardener's Calendar. 

Monticello's Nurseries

Michael Tricomi: : Jefferson had two nurseries at Monticello.

Peggy Cornett: There was the old nursery below the vegetable garden and then the newer nursery was at the east end of the vegetable garden terrace.

Michael Tricomi: The old nursery was just separated into, similar to the vegetable garden, different squares or garden plots. And then the new one was divided into terraces. There was a least 16 different terrace levels to it.

Peggy Cornett: Yeah. the mountain is really a difficult terrain to deal with when you're trying to create a level space. 

Just looking at Jefferson's Garden Book on some of the notes he has about his nursery, it's really remarkable. The rows were numbered and he would write how many seeds or plants were planted in each area. And he does talk about the terraces. This is in 1812, he's talking about the sweet almonds and hard-shelled bitter almonds, peaches, ash seed, scotch fir, Pyracantha, and Cedar of Lebanon, these were all planted in the nursery and they came from Edinburgh, from an acquaintance of his named Mr. Ronaldson. So, he was receiving just gifts from people, not just other nurseries.

Wormley Hughes was skilled at propagating and growing plants in the nursery. But other enslaved gardeners were mentioned, like David Hern, that were skilled at propagating as well.

There were 13 kinds of shrubs, 41 species of ornamental trees, 26 vegetable varieties, six kinds of grasses, 11 nut trees, and 53 fruit tree varieties were recorded in the nursery over time. So it really was an important part of the whole production of Monticello.

Michael Tricomi: For sure. And then, they had an ornamental factor as well. From the design and the layout of them, we talked about the terracing in the one nursery and the beds or the squares in the other, and the organization that went into them, making sure everything was properly labeled and assigned a certain area was really important.

Peggy Cornett: Yeah. Labeling is very important, certainly, now too, of course.

Michael Tricomi: Yes, definitely. But in the old nursery, in 1811, it was surrounded by castor beans that year, which was supposed to be intended, I think, as an animal repellent but also had an ornamental quality to it as well.

Peggy Cornett: Yeah, and it was a living fence, in a way.

Visitor Spotlight

Michael Tricomi: : Now let’s hear from some recent Monticello visitors.

Fruit Trees and Grafting

Michael Tricomi: : Grafting fruit trees was one of the most important tasks in Jefferson’s nurseries. Horticulturist Robert Dowell joined me and Peggy to explain the process.

Robert Dowell: Fast-forwarding to the 21st century, anyone who buys a fruit tree these days is more than likely to buy a grafted tree.  Especially the palm fruits, apples and pears, the stone fruits, peaches, plums, and cherries, almost exclusively will be grafted.

Grafting is a tried-and-true propagation method and it's been around since antiquity. It's really amazing to think that people in ancient times discovered how to surgically detach two pieces of plant and then reattach them together to propagate plants. And certainly it was known in Jefferson's time.

Specifically with fruit trees, if you take a seed of an apple tree and you plant it-- So if I take a Honeycrisp apple and I try and plant that seed-- the resulting tree and fruit that you'll get will not be the same quality of the parent plants.  And I'll have to wait possibly 10 years or more to find that fact out.  Grafting is a form of clonal propagation, so you are preserving the lineage of that variety, so you're guaranteed to have the same quality fruit or flowers or vegetation or whatever the desirable trait is.

You also get that trait much faster. So a grafted fruit tree will often produce fruit it's second or third year in the landscape.  It's usually a good practice to remove those early fruits and let the plant establish itself, but the plant is in a reproductive state, ready to go, so to speak. So it gives you a much shorter time window for production.

The thing with grafting too is that it's its own art form in a way. I've heard  a propagator once described it as carpentry.  Some forms of it are literally like joinery. You're making a cut in the rootstock and a corresponding cut in the scion, and you're interlocking them together, like a joiner will join a piece of furniture.

The Scion is whatever desirable traits you want in the plant. In the case of fruit trees, it might be you want a specific cider apple, a specific fresh eating apple, maybe a certain ripening time. For an ornamental plant, it might be variegated foliage, it might be a weeping habits, flower color.

Peggy Cornett: Yeah. Weeping cherries.

Robert Dowell: Yeah. Any weeping plants sold at nurseries, those will almost always be grafted.

The rootstock is just basically the pedestal that scion is rooted to. And that can lend its own benefits. Some rootstocks are chosen for disease resistance, general adaptability, and controlling size, too. Another point with fruit trees in general is you'll see the terms dwarfing, semi-dwarfing and standard, and these all refer to the ultimate size that grafted tree will achieve depending on what the rootstock is.

There's so many different styles of grafting and techniques that have been developed. But there's two general categories of grafting. There's bench grafting, which is basically grafting at a table with potted stock. The advantage to that is you have a small plant that you can easily move around to an ideal growing environment like a greenhouse. And then the other technique is field grafting, where you're literally grafting out in the field with the elements working with you or against you. And that would've likely been what Jefferson was dealing with in his time was field grafting techniques. And there's all different kinds of techniques and reasons to graft too. The primary reason is to preserve a variety and bring it into fruition earlier, but there's even some cases where if a tree in the landscape is in dire health and it needs an infusion of  vigor, you can do what's called inarching, which is a really interesting grafting technique where you actually plant seedlings at the base of the tree and you graft them into the main trunk. If the root system may have been compromised by something it's a really interesting technique.

I don't know how frequently it's employed but if you open up any historic grafting book, you'll see dozens of different techniques. It's really fascinating to see all the different, innovations people have come up with grafting.

Peggy Cornett: Michael's been grafting some peach trees and I guess you're probably doing them in pots, but Jefferson would've just put them right in the ground.

Michael Tricomi: Straight in the ground. Yeah. He grew his own rootstock too and then, yeah, I think right into the ground, right in the nursery. But we usually buy in rootstock, bare root, and then graft it, pot it, let it grow a little bit, and then we'll plant it out in the orchard.

In The American Gardener's Calendar by Bernard McMahon, he talks about, from season to season, different tasks that are undertaken in the garden. And in April, he mentions grafted trees. This is a time for examining the grafted fruit trees that you have in your nursery. He mentions clay and bandages as a means to hold the graft together. And so he says, "examine the new grafted trees. The clay is sometimes apt to fall off or crack so as to admit air and wet to the grafts." So keeping a nice, good union is really important, trying to eliminate moisture from the graft is really important. He also mentions the rootstock sending up shoots, making sure that it doesn't do that because that can dehydrate the scion wood and ultimately cause your grafted tree to fail. So he mentions the different stages of grafting throughout the year.

Nursery at Tufton

Michael Tricomi: : Last but not least, we wanted to talk about the nursery at Monticello today.

Robert Dowell: We talked before about our greenhouse operations in terms of creating unique growing environments. And so once plants graduate from the greenhouse, then they're moved outside and hardened off. We really like to take advantage of little microclimates within the nursery. We have a great big hybrid oak tree. I call it a hybrid because we don't know exactly what species it is.

Peggy Cornett: Yeah, it's a great tree.

Robert Dowell: It's a massive tree and it creates a giant area of shade in our nursery, which is perfect for growing our shade loving native plants.

Other areas of the nursery, we have designated cold frames, which are basically simple rectangular wooden frames with gravel inside and then landscape fabric over that to keep the weeds down. And in those frames, we'll over winter things in these frames by packing them tightly and then putting white plastic over them to give like a mini greenhouse effect. But this time of year we've pulled back pretty much all the plastic. We're letting the plants get used to the spring weather fluctuations.

Peggy Cornett: I think of the cold frames is like a production line where you're moving things from the greenhouse down to the cold frames and the cold frames to the either mail order or to the shop, and then it just keeps going in a circle.

Robert Dowell: Exactly. Yeah. I feel like half my job sometimes isn't just growing plants, it's moving plants. because we're constantly shuffling things.

Peggy Cornett: Yeah, the idea of a nursery would be things are rotating in and out of it. It's like a staging area, a place to heal plants in or to plant the grafted fruit trees and that sort of thing. And then when they get bigger, you're going to just move them right out into the garden or to the orchard or the landscape.

The best thing that was ever done for that nursery was when they built the lath over top of the cold frames.

Robert Dowell: The pergola. Yeah. That creates the perfect dappled shade area, which most plants tolerate or even prefer. But we also have full sun tables. So we have everything from deep shade to full sun in a very tight area.


Michael Tricomi: : For the first time, we are propagating pomegranates at our nursery.

Robert Dowell: These are Mediterranean plants that are marginally hardy in Virginia. They can survive most winters, but especially when they're very small, it's best to keep them in a protected, typically no colder than 30 degrees in the winter. So these things are frost tolerant, but they can't tolerate much beyond that.

Peggy Cornett: Pomegranates were planted down in the south orchard very early, and that would be the single flowered one that fruited. But we're a little out of their range, I think, here.

Robert Dowell: They're about as hardy as a fig maybe slightly less hardy. But the way I see it, wherever you can grow a fig, pomegranates are worth trying. And they're a great container plant too. You can get them to flower and fruit in a container.

Peggy Cornett: They're really beautiful too. The color is lovely.

Robert Dowell: Mm-Hmm. If it's a fruiting type, the flower is trumpet shaped. It almost looks like a miniature trumpet vine flower.

Peggy Cornett: It's kind of an orange color.

Robert Dowell: Same color, much more stunted with kind of a trumpet shape and then like a frilly, tissue-y petals that kind of come out of that. And then as the fruit ripens, it's like a balloon being inflated, in slow motion.

Peggy Cornett: Behind where the petals were.

Robert Dowell: Yeah. It's fun to watch them grow as season goes on. You can definitely get them to flower in Virginia, but to get the fruit to ripen, it's very difficult. They need a long, hot growing season, so that's why California is the nation's pomegranate grower. They need that Mediterranean climate where they're originally from.


Michael Tricomi: : If you’d like to visit Monticello’s nursery, our spring open houses are on April 27th and May 25th. We’ll sell plants and seeds, and staff will be on hand to answer all of your questions. It's usually a really fun day.

That’s it for April! Thanks for joining us and tune in next month when we’ll take a deep dive into roses.

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Direction and editing by Joan Horn

Sound design by Dennis Hysom

Production by Chad Wollerton and Joan Horn

Bernard McMahon

More on the Philadelphia nurseryman often been described as Thomas Jefferson's gardening mentor and his classic work, The American Gardener's Calendar.

The Nurseries and Fruit Propagation

Jefferson had at least two nurseries: the "old nursery" below the garden wall and the terraced "new nursery," which was an extension of the northeast end of the vegetable garden