Episode 3312

- [Narrator] Agaves date back 10,000 years. And Plant Delights Nursery in North Carolina has one of the most extensive collections in the world. Marty DeHart joins renowned plantsman Tony Avent to showcase some grand specimens with interesting form and habit. Then Troy Marden tours the Wetlands Garden at UT Gardens in Knoxville. This low-lying area features a series of ponds plus a wide variety of native plants that together form a sustainable ecosystem that filters water and provides habitat for wildlife. Join us. Agaves are low maintenance, thrive in full sun, and come in a variety of visually interesting shapes and sizes.

- Big treat today, folks. We're at Plant Delights Juniper Level, and I'm talking with Tony Avent, who is Mr. Plant. Anybody who's a gardener knows who he is. And today, we're talking about one of my loves and one of his, which is agaves. Tony.

- Yeah. Pretty incredible, isn't it, to think that we can grow this here in a climate that could get down into the single digits. Pretty neat. This is a plant that we call agave pseudoferox. And you can go down the taxonomic rabbit holes. It's sold as salmiana ferox, which is a Zone 9 species.

- [Marty] You're not Zone 9.

- [Tony] We're not Zone 9, have never been Zone 9. And so what's happened, we realized, is the pre-Columbians, as they moved up from Mexico into what's now the United States, began bringing their favorite agave species that they used for alcohol, they used for sewing-

- Tequila. Yeah.

- For all kinds of things.

- Mezcal.

- [Tony] And moved them up north. And they began breeding with more cold hardy things unbeknownst to them are these wonderful plants for gardens.

- Sort of natural hybrids that just sort of happened through people migrating and bringing their plants with them.

- Which has happened since the beginning of time. Yeah, pretty neat.

- It sure has.

- So this is one called Green Goblet, and it's one of the largest of the hardy forms.

- Goblet?

- Goblet.

- [Marty] That seems like a misnomer. Look at it, it's like, should be Green Vat.

- It does. I think it was named when it was much smaller.

- [Marty] I guess so. and I noticed you've got it planted. Tell me a little bit about drainage and things like this.

- External drainage means how the water sheets off. So we always put those on slopes and never flatter.

- So the water flows away from the plant.

- [Tony] Flows away. The second thing is internal drainage. How well is that soil drained? How fast, when it rains in there, does the water get out?

- [Marty] So it percolates down through the soil quickly?

- Exactly.

- In other words, clay is not your friend, tight clay.

- Unamended clay is not your friend.

- Yes. Correct.

- Yes What they hate is water in the wintertime. So we always recommend on the smaller ones, planting a shrub on the north side where it will not interfere with the light, but will help suck the moisture out.

- [Marty] What a good tip.

- [Tony] And that is a huge difference maker in growing agaves in cold winter climates.

- [Marty] That is a great tip.

- The other thing is do not plant agaves in cold climates in the fall. You've gotta get 'em in summer. They have to build up enough mass to be able to sheet the water away from the roots.

- Gotcha.

- But if you wanna see growth, you pour the water to 'em in the summertime and stop in the fall.

- Okay, so a dry winter is what they really want.

- Absolutely.

- It's 'cause they rot out in the winter if the roots are wet and cold.

- That's the key.

- Gotcha. Makes perfect sense. How about fertilizing these things? Do you ever?

- We don't use any chemical fertilizers in the garden. We do it all organically. So when we build the beds, so all of these beds are, we start with our mix of whatever our native soil is, we mix half compost into that. We take that mix and mix it 50% with a product called PermaTill, which is this. And PermaTill is a pop slate, so it's like a pomace material. It's got air in it and all around it.

- [Marty] They heat it and expands, yeah.

- [Tony] Yeah, it's actually used for making lightweight concrete block, and this is the leftover residue from that process.

- Wow.

- [Tony] But it's a great product. It also has a pH of 8.2.

- [Marty] Oh, I did not know that.

- And agaves like higher pHs. They don't require it, but they really like it. So you mix this in with your native soil and then you've got a high pH that the agaves absolutely love.

- [Marty] Well, how about we go talk about some particularly hardy varieties.

- Okay. Sounds cool.

- That people even in the colder sections of Tennessee could grow successfully.

- All right, sounds great.

- [Marty] Let's talk about this one.

- Okay. This is one of the hardiest. This is one of the weirdest agaves. This is agave straight, which means long straight leaves.

- It looks almost more like a yucca, you know?

- It does, doesn't it? Now, the interesting thing about this, almost all agaves flower and then they die. This one does not. This one and the ones related to this. So recently when somebody was working on the agave family tree, they looked at these and they said, "You know what, these actually come up at a weird place on the family tree. Let's slice off that limb and take this out of the genus agave. And it became a new genus called icano agave, which means agave that looks sort of like a porcupine.

- Yeah. Okay.

- So, but it's still in the agave group, but really fascinating plant. And like I say, it does not die after flowering, and this is one that flowers every single year.

- Okay, so it throws up the typical agave stalk with a bit.

- Yeah, Flowers look just like it.

- Ivory bells hanging, yeah.

- [Tony] Just like an agave, but fascinating little plant. So that's one of the very hardy ones.

- And is this about as big as it gets would you say?

- This is mature size.

- This is mature. Okay.

- Yeah. Yep.

- So that's about like four by three maybe.

- Yeah, exactly. Yeah, absolutely.

- Okay.

- So this is another of those odd agaves, they got chopped off the family tree just this year. This is another very odd plant. You see it has no spines.

- Yeah.

- This is known as agave bracteosa. So when they chopped it off, they said this becomes a new agave genus called paleo agave.

- Old agave.

- Yeah. So it's the only one in its group. This one hangs off the rock cliffs. You go up into northern Mexico, about 8,000 feet, it's just dripping off the cliffs. It's a fascinating plant.

- [Marty] It's almost curly on the end.

- [Tony] It is. It's very easy to grow. And this is one that I think has, we found, has done very well in some pretty cold temper tempers.

- Colder climates. Okay.

- [Tony] So bracteosa.

- Bracteosa. But it's one that blooms and dies when it eventually blooms?

- This one does bloom and die, but the ones that bloom and die, the offsets don't die. So it's only the main clump that dies.

- Yeah, don't they call those pups? They put out the babies around the base and...

- [Tony] It's just like a bromeliad that people grow as a houseplant.

- [Marty] Exactly. Good example, yeah. Well that's really handsome. And I really like the kind of light blue-green color of that new growth. That's handsome. Wow.

- Yeah. This is pretty neat of the really large blue agaves. This is the hardiest. This is called agave ovatifolia, common name, the whale's tongue agave.

- Whale's tongue agave.

- So this thing really gets amazing. It'll get four foot tall, seven foot across before it flowers. It was one of the more recent discoveries. This actually was not realized to be a new species until the '80s from northern Mexico.

- Really?

- [Tony] Now, unlike the others we've looked at, this one never offsets. So it grows its entire life to flower one time. Now in the wild, they're called century plants because it takes them right at a hundred years.

- [Marty] Yeah, that's to get big enough to throw up that bloom.

- [Tony] Yeah, and it's a big bloom. So this one then cultivation, because where we are, we get 46 inches of rain a year, so it blooms six times as fast, so generally 16 years.

- [Marty] Okay. So our humidity basically ramps up the lifecycle of all of this.

- [Tony] The humidity and the moisture. Because where these grow in the wild, they may get eight to 10 inches of rain a year.

- Oh, I see. Yeah. So like we're giving it steroids almost.

- Exactly. Yeah. As I mentioned earlier, it likes the moisture in the summer, so they grow like crazy. And then when it flowers, it produces this enormous 25 foot spike and which is incredibly spectacular and-

- [Marty] I've seen pictures of you guys up on big ladders taking, collecting seed and pollinating and doing all of that. So this is a species that depends entirely on seed to keep going.

- [Tony] It does. Absolutely. Now, what is also interesting, once it finishes seed, this species will often produce baby plantlets up on the old seed pods. So if you've got a tall ladder, you can climb up there, you can actually take these little plants off that are clonal versions of this.

- Adventitious little babies.

- Yes, absolutely.

- [Marty] Oh, so and then you just pop those up and...

- [Tony] And then you got a new plant.

- Wow, so sweet.

- Doesn't do it all the time, but it does it I'd say 50% of the time with the flower.

- As long as you're not scared of heights, you got new plants.

- You're good to go.

- Yeah. Sounds great. That's a gorgeous specimen though, my gosh. It's got some serious weaponry on it.

- It does. Yes. It's a great plant to demonstrate Darwinism, you know, people who are not particularly keen on making good decisions. Yes, can't get damaged.

- Or observant. Yeah.

- Or observant. Yeah. It's a great plant to induce mindfulness in the garden.

- There you go.

- [Tony] This is agave lechuguilla. This is one of the real hardy ones. It looks completely different from everything we've looked at before.

- [Marty] No kidding, it's low and it looks almost wind swept.

- It does. It's one that multiplies well, very slow to flower. Matter of fact, we've never had one flower in 30 years. In the wild, this is known as shin digger plant because it just punches people in the shin when you try to walk through it. Because in the deserts like this, it makes really large populations. So this is probably a 20-year-old patch-

- [Marty] Oh wow.

- [Tony] To get that big.

- So it's very slow to spread.

- [Tony] It is, tut it's a really nice addition to the agaves

- - I love this sculptural effect of it. It's really such a contrast in texture to everything around it.

- [Tony] It really is a lovely little plant.

- [Marty] Yeah, I love the shin digger though. I can see it's just the right height to stab you good.

- It is. It is.

- [Marty] This one looks great.

- Well, this is actually a hybrid with the one we looked at earlier, agave bracteosa, which again, is no longer in agave. So that was crossed with one called agave lophantha, which is another great one for cold climates, and it produced this wonderful plant with absolutely no spines.

- Oh, good.

- And then it has this central band, which is lighter now.

- Oh, I see that

- The color fades during the year. That comes from agave lophantha.

- I see that. You can see this subtle lighter band up the middle of the blade.

- Yeah. Yeah. And as the new growth comes out, it's more prominent, but a wonderful plant. I'm not aware that this has ever flowered anywhere in the world. This is a cultivar called Mateo, very slow to offset. We probably had this in for a decade before we had a single offset.

- Wow.

- So now we've got a few.

- [Marty] Are these babies coming off of it here?

- These are babies.

- Okay.

- Exactly. So those could be taken off and shared with friends, give 'em at the plant sale, give 'em away, start your own nursery. All kinds of options. But a really great plant, I think. Does need to be tried out in a lot more areas. I think it has good hardiness.

- [Marty] Okay, so this would be a really good one for even people like around Nashville where it's pretty cold to really give this one a shot.

- Yeah. We've had this through seven degrees. That's the coldest we've been in the last 20 years. So it'd be worth a shot.

- We've been a lot colder than that. But it would certainly be worthwhile to give it a, especially if you've got the right, you know, you plant it correctly, as you were talking about earlier, and you put it in the right location.

- Yep.

- Yeah. I see the stripes.

- [Tony] Okay, this is the parent of the agave Mateo. This is agave lophantha and this is a cultivar called Splendida. This is one that you can make these nice masses. This was one quart pot. And see how it's filled in and really made a beautiful thing. And it just wraps this way around rocks. So always love to put it in rocks.

- Just gorgeous.

- [Tony] It's a really easy one to grow. And again, one of the most hardy species that we've tested.

- [Marty] And I love the stripes on the leaves. They're really distinct with the species and it's so decorative.

- [Tony] Yeah, there's just not a lot with variegation that will survive in cold areas. So this really nice to have that it gives you a little yellow variegation.

- [Marty] Oh, that's really beautiful. How long did it take for this mass to get like this?

- This would be a 20-year-old mass-

- 20-year-old. Okay. Okay.

- To go from a quart pot. Of course you could divide that now and get probably 300 out of there.

- [Marty] Yeah, so I mean, it does. It's pretty quick. It's really gorgeous. What a spectacular group.

- Well, these are, they really are. So in terms of hardy agaves, it didn't take us but a few years to exhaust all the potential hardy agaves for, you know, zone seven. And so the only way we get more is to breed those. So we bought us the 21 foot ladder and we hired people that don't mind climbing up those ladders. And all the ones you see here, like this, are all our hybrid.

- Oh my God.

- So we create this. So all of these, we are really looking for good blue foliage plants primarily, good leaf imprints, which are really-

- Yes, I love this texture. That's really gorgeous.

- Yeah, we actually select for the bud imprints, but you just get all kinds of forms.

- [Marty] They're happy to cross. It's not hard to get into specific hybrids with them?

- [Tony] It depends. It's very interesting. You'd normally would look at what's closely related, but we have not found that to be true. We've crossed some of the most distantly related things.

- Wow.

- Now the problem is once you've crossed 'em a couple times, they don't tend to want to cross anymore. It's like, okay, we've done enough.

- [Marty] Done that. Tired of him. Yeah. Yeah.

- Tired of him, yeah. Let's find me another mate. So we're always experimenting, but you only have so many agaves flowering each year. So we actually save the pollen in a refrigerator. And we pull it out and we try it and find out who will cross with who. There's just been so few agave breeders because people would rather breed plants that don't require ladders.

- [Marty] Well, it's kind of a specialty thing, yeah.

- [Tony] It is. So we're in new territory now, but it's really fun and a lot of great successes.

- Oh, well, I'm just thrilled to see so many new varieties coming into life and that we can all trial in our colder climates. I mean, I think of us as 6B, but they say 7A. But I would try these, I mean, in the right spot. Why not?

- Yeah, again, plan 'em early, select the right ones, good drainage, good slope, and put something to keep the moisture off of 'em in the winter.

- That's the recipe. Well, listen, I wanna thank you so much. This has just been such a delight.

- Thank you very much.

- Wetlands and retention areas are an important part of landscapes. And in cities, a lot of times now, there actually are requirements in new neighborhoods for water retention areas. So I am at the UT Garden in Knoxville, Tennessee with Andrea Ludwig, and she's going to tell us about their wetland area here at the UT Garden.

- Yes.

- Andrea, thanks for being with us. And fill me in a little bit on the design and development of this wetland here.

- Absolutely. Well, thank you for your interest in this topic. Yeah, having a water feature in your yard can be a really big interest, and bring new wildlife and new plants, new planting opportunities to your yard. Tennessee's a wet state, so we have a lot of precipitation and a lot of water to manage in the landscape because of that. And so here at the wetland gardens at the UT Gardens, we're doing just that. This area is a naturally low lying area and it catches that runoff from about 6-1/2 acres of UT gardens and some of the parking areas and structures and that water collects here. And so before we turned it into a wetland, it collected that water because of the natural low lying of the area.

- Right, so it was just kind of a low spot on the property anyway.

- Absolutely. And that water would stick around long enough to create a challenge for mowing and a lot of, you know, of the plants that they were planting here, but not long enough to really create a natural wetland. So it was kind of that in-between zone and made it a real challenging part of the landscape.

- And probably it also was a mosquito breeding area and...

- Potentially, yes. Yes.

- Potentially, yes.

- And so we needed to give this area just a nudge towards more of the actual wetland function that we needed here. And so to do that, we did some excavation. We did a little bit of grading and groundwork. We brought in some liners to make these permanent pools here.

- And then we were able to plant the native wetland plants that you see here, because we were able to change the hydrology.

- [Troy] So even though this looks completely natural, it is a built landscape.

- It is.

- [Troy] And the ponds are actually lined.

- They are, yes.

- Yeah.

- [Andrea] The ponds are lined up to about the water's edge. And then in between the ponds, we have four ponds total, actually three of which are lined. One is not lined, so it's more of your kind of like seasonal wetland.

- It comes and goes.

- Yep.

- Yeah.

- And then these three perennial ponds. In between here though, when it rains, we've got porous land in between. And so it can accept that runoff, but then the water recedes and soaks into the ground in between rain events.

- Gotcha. This is really built to be an ecosystem.

- [Andrea] Absolutely. That is exactly right. So we are trying to manage this challenging water area and then turning it into an ecosystem, really leveraging the natural functions of a wetland to enhance the beauty, but then also the function of the landscape. So we're absorbing runoff, we're also capturing any potential pollutants that are in that runoff, and then we're creating these beautiful spaces to plant.

- In this setting, you have, I'm assuming, dragonflies.

- Yes.

- Probably frogs.

- Yes. Absolutely.

- [Troy] What are kinds of wildlife do you experience here in the wetland?

- Yeah, so in addition to dragonflies, and I'll talk a little bit more about dragonflies in a moment, but a lot of our terrestrial insects start their life in the water. And so we get a lot of the aquatic insects in our wetland ponds here. So damselflies, dragonflies, water beetles, water striders, mayflies, stone flies. These are insects that we recognize in their terrestrial form, but they actually start their life in the water. With dragonflies in particular, I'm glad you brought those up, because we actually create a wetland to have the habitat that dragonflies need because dragonflies and damselflies in particular are mosquito predators. And so you can imagine when we talk about wetlands in our residential and urban spaces, mosquitoes is the number one question, right?

- Right, a big concern.

- The number one challenge. Absolutely. But if we can build the ecosystem here, provide the habitat for those predators, that means we have a functioning food web, we've got our damselflies, dragonflies, water beetles, things are gonna eat mosquitoes in their larval stage. And then that way, they don't have a chance to make it out and bite us. So we really are recreating that food web, creating the habitat for those predators and creating that ecosystem

- It's amazing to me that you can do that in a small space like this, because where we're standing, even though it probably looks rather large on camera, it's, you know, the walkway is 40 feet or so.

- Yep.

- The pond is maybe 30 by 50, something like that.

- Absolutely. Yep.

- It's not a huge space and it's something that could be done with the right setting. If you had a low spot in your yard, if you had, you know, an area that naturally collected water that you were concerned about or maybe wanted to do something pretty with, you could create a natural area like this.

- Absolutely. Yeah. Something like this is feasible in, you know, in your yard. But even if you just have a downspout, I've seen dragonfly habitats. Simple downspout is a source of that runoff water from your house. And feeding that into a really small kind of micro wetland, that's enough. As long as you've got that permanent pool of water, you've got some vegetation that is emerging from the water, that's what the dragonflies need to complete their lifecycle. So it's this emergent vegetation around the edge, that's so important.

- [Tony] So let's talk then a little bit about vegetation.

- Let's do.

- Part of it. What kind of plants are going to thrive in this sort of setting?

- Lots of different types of plants. And you can kind of think of a wetland edge as having different zones. So we'll have plants that will thrive in kind of that deep water environment, so our submerged aquatic vegetation, so think lily pads. This spider dock right here is a great example. That's in that deeper water environment. When we get closer to the edge, about four inches of submerged area. We've got our broadleaf arrowhead, bull tongue arrowhead. We've got pyickerelweed, wonderful purple blooms that attracts pollinators as well. And that's the emergent vegetation that the dragonfly nymphs will climb out onto.

- Climb out on.

- And do take off their exoskeleton and then morphosize into their adult form. So that emergent layer, right at the water's edge, you can see riparian plants and water loving species. We've got some lizards tail right here.

- We've got some of our native hibiscus, our marshmallow back in the background there. Some asters and goldenrod coming in. And then you can think also above the water line, some of these shrubs. These are again riparian plants you would find around water bodies naturally.

- Sure. I notice on the surface of the water, I think for those of us who have ornamental ponds, let's just call them ornamental ponds, koi ponds, goldfish ponds, we're growing water lilies, that kind of thing. Duckweed is sort of our nemesis in that situation. But here, it's an important part of what's going on.

- [Andrea] It is, yes. Duckweed is a really interesting and valuable plant. Some folks might confuse it with it being algae. It's actually a vascular plant as you know. It's got a leaf and a root, so it's a vascular plant.

- And it just floats on the water surface.

- It just floats on the water surface. It is a valuable food source for a lot of wildlife, in particular ducks. But it's really high nutritious, very dense food for a lot of wildlife. And it also helps to keep our water clean. It keeps it shaded. So the temperature of the water column's cooler, that means more dissolved oxygen in it. And it can help take out some of those pollutants in our water.

- Right, and because it covers the water surface, it's not allowing sunlight down. So that actually probably helps with the algae issue.

- Absolutely.

- Which is a negative.

- Yes. Yes, that is true.

- Yeah.

- So that we can be a really great part of an ecosystem.

- So even though this area seems like it might be fairly large for an average homeowner, then you can shrink this down.

- Scale it down.

- You can scale it down to whatever size might fit in your own yard.

- Absolutely. I would throw out a tip that about two feet deep is the depth of the permanent pool that we wanna target, because that will, in these dry times like we're having right now, that will be able to withstand the kind of the evapotranspiration losses in a line system.

- So a minimum of two feet.

- [Andrea] Yeah, two feet will get you that permanent pool and that habitat that we need for our predators and the whole ecosystem to thrive.

- Awesome. Thank you so much for sharing your knowledge with us today and for letting our viewers know that something like this is possible. You can create these very viable, lively ecosystems right at home in your own backyard.

- Absolutely. Thanks for having me.

- Thank you.

- Cutting herbs to dry are basically all the same for all varieties. On the monarda or the bee balm, if you're gonna use these for reeds, then you wanna wait till all the flowers are completely open. I usually snip a pretty long stem. And then if I was going to hang them and dry 'em, I would strip the leaves. Just run your finger and do about a fistful of the flowers, rubber band them and hang them to dry in a warm, dark place. The lavender, I'm gonna set this down here, the lavender is all the same as well. But I have a lot of lavender harvest. I don't do individual stems. I grab as much as I can in my hand and I just cut. And what I do is you can see where the stems start, they're the brighter green and the old growth is the silver green. So you'd get a big handful of this as well, rubber band it, hanging it upside down in a warm, dark spot. It's good to have a fan or some kind of ventilation. Really there's two kinds of lavenders, Spanish and French. And this is a French lavender and I find that they're good for cutting and drawing because the stems are longer. It's easy to do. Just remember, you wanna do it when there's not any moisture on it. And hang it up to dry and make sure it's good and dry before you craft with it or use it for culinary purposes. Feverfew is my other favorite thing to dry for flowers. If you can see it here, looks like little daisies. And as that dries, the little daisy, the white part kind of shrivels up, but it's still very pretty for reeds and stuff. And if you wanna use it for medicinal things, that's good as well. Again, you'd cut the stem, strip the leaves, and hang it upside down to dry.

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