In this episode of Gardening Unplugged, Grounds and Research Supervisor Jeremy Schmidt discusses the fall maintenance routine of many popular perennials that can be found at Juniper Level Botanic Garden as well as Plant Delights Nursery. Find out which plants to leave alone and which ones can benefit from pruning during this transitional time of year.
Fall Perennials featured in this video:
- Colocasia (Elephant Ear)
- Hedychium (Ginger Lily)
- Aspidistra (Cast Iron Plant)
- Hosta plantaginea
- Cycas (Sago Palm)
- Athyrium (Japanese Painted Fern)
- Hostas (Plantain Lily)
- Amorphophallus (Voodoo Lily)
- Dryopteris sieboldii (Siebold's Wood Fern)
- Dryopteris erythrosora 'Brilliance' (Brilliance Autmn Fern)
- Pyrrosia (Tongue Fern)
- Hellebores (Lenten Rose)
- Edgeworthia (Paper Plant)
Welcome, my name is Jeremy Schmidt. I head up the research and grounds here at Plant Delights Nursery/Juniper level Botanic Gardens and today we're talking about fall garden maintenance. It's kind of... kind of early fall, I guess you could say. How many people here have a garden? Most of you. How many people here love to garden? All right, yep. One of my favorite things about gardening is that there's always something that you can do in the garden. It's more of the process of gardening for me than it is standing around and doing nothing in the garden. My enjoyment comes from maintaining it as much as seeing it and watching it grow. So, this time of year there are certainly a few things happening.
Fall is a Great Time to Transplant Woody Perennials
For one, most woody plants, most of your canopy, most of your trees and shrubs, they're transitioning from summer growth. And spring growth, obviously is long gone, and now they're starting to focus on roots. So, if you want to transplant or if you want to add new things to your garden, new woody plants, now's a great time to do. It either to transplant a woody plant from over here to here or to buy that number 15-gallon container and get it in the ground. A good time to do that.
This is the time of year when some of those late spring early summer blooming plants, they're totally finished. Maybe there are some things that you do not want to have set seed and so some things you can cut back. Some things you can, as you're walking around your garden, you might see things that are flopping onto other plants. A good time of year not only to audit that to cut things back that need to be cut back that might be going towards dormancy, die back plants especially, to get them off of something else. But also, for almost every other plant in the garden, not just woody plants, but many other herbaceous things, not including your tropicals. It's a good time of year to move them as well. So, as you're walking around you see the things that did too well in comparison to their neighbor now's a good time to move a lot of those things. Again, colocasias, maybe hedychiums, some of those tropical leafed things, let's hold off until the crab grass starts growing again next year to move those.
But let's walk around. We'll look at a few things and as you see things that you might recognize from your own garden or see plants that you would wonder how you would maintain, feel free to just fire away and ask me what you would do with this plant. But I'll point out a few things.
Aspidistra Have Two-Year Leaves
Some of the trickiest plants or some of the perennials in the garden that it's easy to make a mistake with and that it's best not to prune are some evergreen perennials that have two-year leaves. Leaves that last two years instead of just one. So, aspidistra is a very good example of this. I have made the mistake in my own garden of cutting all of the leaves back in May, just as the new foliage is emerging and that actually damages the plant. They're not able to get all of the energy that they need from those one-year-old leaves. So, the best time of year to prune these back is actually right about now. So, if you look down in here, see the garden crew is so good at this that I don't have anything to prune for you today because they got it all. They are on top of it. But if you look closely, you'll see these little stubs. All of those were two-year-old leaves that looked tired. They're looking to be about done with their usable life. But whenever a plant puts up a leaf, you know, it’s putting up a solar panel and it's making an investment. It needs enough time and the right conditions to get a return on that investment and if you remove that leaf before it's time, then the plant ends up with a loss. And so now is the right time, two-year-old aspidistra leaves have served their purpose and now is a great time to cut those back.
Wait Before Pruning Hostas
Other plants, more from a design aspect, most hostas. A lot of their leaves are looking pretty tired but it's not necessarily a good time yet to cut them back because most hostas, not all, but most hostas are not going to put up new leaves anymore this year. The exception being Hosta plantaginea and the hybrids with plantaginea which we do have here in the nursery for sale today. That species of hosta actually puts up new leaves this time of year. Very, very cool but a hosta like this... I wouldn't cut it back yet. Wait until it's just too ugly to look at. Let's see what else do we have today.
Q: I have a question about aspidistra. I've got a fairly large clump and I was wondering if I could divide it.
A: Great time of year to do just that.
Q: Just dig it up?
A: Dig it up. You can actually dig... aspidistras are about the same difficulty to move as let's say a day lily. Just get that shovel in there, chop it up, make sure you've got several eyes, and then move that plug wherever you want. If you're moving it with the leaves on, which I would suggest doing, it might need some support to stay upright through the year or until it really puts down new roots, but it is a good time of year to move aspidistra.
Q: I've got a lantana that's really over-grown and I'd like to move it.
Q: Yeah, it still has some flowers on it.
A: Yeah, but it's getting perhaps… for marginally hearty plant like lantana, 7B Hardy sometimes they're 7A, the hardiest clones are, it's getting a little, maybe a little bit late but you could probably move it and you could probably cut it back. You're going to probably want to cut it back anyway if that's the issue. I mean if it's too big then then might as well give it a try.
Don't Cut Back Cycads or Cycas
One plant I would not suggest cutting back yet would be any cycads. Cycad, when we get much below 15 or 20 degrees it's, going to toast all of those leaves anyway. So, unless you have a dead leaf that is no longer connected to the plant, I wouldn't touch it. If a leaf's dead the plant won't know it's gone anyway so you might as well cut it at any time of year. But some things I wouldn't cut back a cycas, a cycad, even if it's getting onto something else. With a plant like that, I'd rather cut back whatever else it's getting on too. You can always feel free to cut back dead flowering stems, like hosta stems, that's an easy call. There's really never a time when that's hurtful to the plant.
Cut Back Early Summer Perennials in Fall to Prevent Seeding
It can be... you can strategically cut back other plants to keep them from seeding, however. Again, a lot of those early summering plants, especially in the Aster family, those seeds are becoming ripe now if they haven't already. And so, this might be the time to cut back seed heads that you don't want to seed around the garden. It's always something to think about. And a plant often will put energy... it will prioritize putting energy into its seed production over putting energy into its... into its leaves, into its offsetting, into its into new flowers. And so, a lot of times cutting back old seed heads as they're ripening before that plant is able to put all that energy into it, is going to free up that energy maybe to go into a new flush of leaves or flowers, especially with herbaceous plants.
And many deciduous ferns, like athyrium. Most athyriums that we grow around here are deciduous. They do die back to the ground in the winter. If you've got some pretty beat up fern fronds, feel free to just pop those out clip those off. The more of that the more aggressive you are with some deciduous ferns the more likely they are to put out a few new fronds before frost. And I would say that we're getting almost too late in the year to do that but we're still, I think, in that window to be pretty aggressive with our cutbacks of tired deciduous fern fronds.
Q: When the plant looks bad, how do I know the difference between I just killed it and it's just changing? Because my yard, yeah there's a lot of dead there.
A: Part of that's just living out in your garden knowing what a plant does through the seasons. You know there's a lot of plants like hostas that are getting pretty tired this time of year. And you've done everything that you need to do and that that hosta is as healthy as it has ever been but it's getting towards the end of its year, of its cycle. Other plants like some aroids, like amorphophallus, no matter what you do, the leaves are going to tip over and they will go away. The roots, in the case of amorphophallus, the roots also will die. You'll have no roots and no shoots here pretty soon, no matter what you've done. So, part of it is just experience. Plenty of resources, our website of course, any plant that we sell or have sold we might have some insight about what to do. What it's going to do. Its life cycle.
And don't get too attached to any one plant ever because part of being a great gardener is killing a whole lot of plants.
Q: Oh, I'm a fabulous gardener.
A: Here we go, see. Great!
So deciduous ferns, yes. However, many evergreen ferns, especially ones that seem to grow a little slower, Dryopteris sieboldii, as as I learned today, is one that if you cut back the leaves, even if they're a little beat up, you might kill that plant. And so sometimes, just just let it be.
Q: Is that 'Brilliance'?
A: No that's a that's a different Dryopteris. Dryopteris sieboldii is kind of a weird, it doesn't look like other ones. Pyrrosia, some of those big leather leaf ferns that they've obviously invested a lot of energy into that leaf into that frond you might want to think twice before cutting it back. If it has a lot of energy left in it that the plant might be able to cannibalize for new leaves. It might not have made that return on its investment yet and you might be setting the plant back.
Q: Can I ask about hydrangeas?
Q: About which ones to cut back, I know it's kind of complicated...
A: Somewhat, it's again, a lot of resources online. The blue ones those kinds of things you can generally... those bloom more on new wood to my understanding. Oak leaf hydrangeas, of course, bloom on old wood. So, any that bloom on newer wood, right now is not a bad time to prune them if you don't like the look of the spent bracks. You know like behind you there that one. If you need to cut back some of the bracks you can. Honestly, I've not, I don't have much experience with this with this particular one so I wouldn't know if I was going to cut that all the way back or not what would happen. Here are some amorphophallus like I was mentioning earlier. They're tipping over they're getting tired but that's just its time. We did everything we needed to do to make this plant very happy and it's... it's just done, so...That's about all I have. Does anybody have any more questions about things that they can do in the fall for their garden?
Q: What about hellebores that are looking bad?
A: Ah, that's a that's a good question. Yeah, the hellebores in this garden and Juniper Level Botanic Garden, we usually prune those leaves back late winter. And by late winter we're talking January, early February. We want those leaves to stay on there really until they start to throw up flower buds which is a January February thing for most of them. These are a little beat up, perhaps they had a little bit too much sunlight, maybe they dried out at some point, that's generally what's going to cause it in in the garden. If there's any way to keep these and to put up with those leaves, they are still going to uh they're going to photosynthesize and feed the plant. So, if there's any way to keep them on as long as possible that's the best that's the best call. And then clip them off as those new flower buds are beginning to swell.
Raking Leaves - An Aesthetic and Ecological Choice
And as far as, you know, let's fast forward another month or two. Just a quick thought about leaf cleanup and raking leaves, that sort of thing. That's an aesthetic more of an aesthetic call so... I know that there's a lot of things, like on Facebook now, about - don't rake your yard ever, in fact don't ever mow your grass and don't do anything in your garden because it's all about bugs and everything else. That's partially true. When we rake the leaves, we rake up the dormant structures of wintering insects, uh good ones and bad ones. So, it uh it's one of those balances. It also, I mean, most plants are self-mulching. I mean let's face it, and that's not all bad. It is an aesthetic choice, and it is in ecological choice. You know, as far as the insect life, some fungus some bacteria they will also winter. Nematodes are another one that they might be a problem for you and so if you have an issue let's say with Southern blight. That's one when you see it and it's kind of past Southern blight season but when you see it you need to get all the mulch up and a little bit of the soil even put it in a trash bag and put it in the dumpster. So, there are times when you absolutely need to clean up all the leaves you can but for the most part you know here in this garden, we do clean up most of our leaves. But for us, it's an aesthetic decision and it is a decision made on behalf of many of our tiny plants here. We've got a lot of plants that are not going to be able to compete with leaf mulch. However, in most home gardens, that's not the case. If you've got larger perennials or bigger bulbs that are just going to shoot up through five or six inches of leaves from the previous season hey that might be great it might be a good way to keep some of the weeds down. It might help keep the soil cooler as the season goes on and the soil gets hot holds some of the moisture in. So, there's pros and cons to leaf cleanup, of course.
Q: Anything special about Oak trees because I hear that their leaves never break down and I am surrounded by these hundred-foot-tall oak trees. I mean we're talking a lot of Oak leaves.
A: Yeah, well I'll tell you what I mean we're talking for winter open house. Bring me some of the leaves of that Oak that were on that tree 40 years ago.
Q: Well, I can't wait 40 years...
A: No, leaves that were there 40 years ago they do break down. They might... it depends on the amount of moisture, that's a big one. If there's moisture in the ground, they'll break down pretty quickly. The more life that's in the soil, microbial life, you're going to... they'll break down much more quickly. And also, they'll break down some of those compounds, you know you hear about things like tannic acid, stuff that is in oak leaves, but that's more that's broken down by the mic the microscopic life of this soil. Same thing as walnut trees. If you can clean up the walnuts, you probably will want to do that. But you hear that it kills all the plants under it because it makes an herbicide of its own. That's most prevalent in the fruits clean those up you'll be all right. Keep the soil moist and mulched and the microbes actually break down, what is it, juglone or whatever compound it has that is actually it kills other plants. But your big cut back stuff like that in in my garden and in this garden some things you wait until they absolutely freeze. and they're done plant doesn't know they're gone but do you have any more questions?
A: Okay fire away.
Q: Don't go insane.
A: Too late.
Q: Welcome to my club. There is this yellow weed that's appearing, it's like a string it feels like sticky string, it just keeps winding over everything. I took it to have someone look at it he told me I needed to burn everything and I'm thinking okay yeah, I need to get a second opinion.
A: Is that there's a parasitic, there's a parasitic weed that can do that, but I think it's specific to certain kinds of plants.
Q: It is hitting everything in my garden. It is just going from here, to here, to here, to here. Wrapping over everything. I keep pulling it out and it feels like I said sticky string it sticks together.
A: I'd send a picture into the NC State Extension, and they should be able to answer that for you.
Q: I thought, burning everything down, I'm not a pyromaniac...
A: It works. I mean it does have that effect. It'll finish it'll work, yeah. well, I mean yeah, a nuclear strike. You know if you can get, if it gets down deep enough that… yeah Napalm works that's true. What's question number two?
Q: Edgeworthia. It's been dying off branch by branch. I'm left with one branch at this point. Should I... originally there was a tree and we cut it down so now it's in the sun I'm assuming it's the sun that's annoying it.
A: It doesn't, they don't mind, they can handle quite a bit of sun if they have quite a bit of water. If they dry out in the sun, they wilt and then they will decline. So, my recommendation is move it now. This is the time to do it. So, you can move it bring it back into the shade or plant the shade right back in there and so in a year or two it can be in some shade. In the meantime, if you want to leave it there make sure that it is it is moist.
Q: Third question. So, when I'm working front yard the front garden there's nothing there's no worms. nothing. And I've gone down like six inches I've flipped it over there's nothing. I'm happy not to bump into worms however I do know the plants and stuff need it. What do I do to make it I feel like it's dead soil.
A: You need moisture, and you need an organic layer. Those two things are going to be best. That's why we use triple shred here triple shred mulch. It looks good but another thing that triple shred does is it breaks down. It rots away. We want our mulch to rot away because that is feeding the soil and then the soil can feed the plants. So, if you feel like you have dead soil check and see if it gets too dry that's number one or stays too wet. Both extremes but most of the beneficial aerobic microbes are going to need consistently moist soil. Soil that has air in it and mulch of some kind so that that there's like extreme humidity layer just out of sight under the mulch and that's where earthworms are. They're going to prefer that but then the microbes, the things you need that there's a couple billion of them in a teaspoon, that's those kind of things. If you don't have that, then your garden, except for a few plants, is going to struggle.
Q: We put compost in so should I put more compost and then the triple bark or just the triple bark instead of more compost.
A: Watch the moisture first. that's that would start there if you've got compost keep it mulched if you see bare soil then you're not going to it's unlikely unless you're watering every day to have a large population of beneficial microbes in it. Okay, all right, thank you very much.