 Welcome everybody. Welcome to the Spring Fever Garden Forms where we connect you, the gardeners, with experts at North Dakota State University. My name is Tom Cobb. I'm an extension horticulturist in the Department of Plant Sciences, and I'm here with Scott Swanson, an electronic media specialist in the Department of Aeroculture Communications. This is the first of our four Spring Fever Garden Forms, and tonight our theme is flower gardens. The format we use is the one we always use. We start with about a 20 minute presentation followed by about 10 to 15 minutes of questions and answers, and we really do invite your questions. So if you have a question, just slide your browser down to the bottom of the screen and a question and answer box will appear and then type in your question. Now please keep the questions relevant to the topic. Okay, we're not going to be not going to talk about tomatoes or birch trees tonight, okay. And we will get to as many questions as we can time permitting, and we will stay on schedule. Okay, so let's get started and talk about dividing perennial flowers. Prennials are the showstoppers of flower gardens, and knowing when, how, and how often to divide them is key to keeping these plants vigorous. Here to teach us how to dig and divide perennials is Don Kinsler. Don's a native of Lisbon, North Dakota, and he writes weekly gardening columns and newspapers. He hosts lots of radio programs during the growing season, and he has a weekly podcast called Growing Together. Don is the NDSU Extension Agent for Horticulture in Cass County. Don, welcome to the forums. Well, thank you, Tom. And it's a pleasure to be here this evening and welcome everyone. Well, I love all phases of gardening, including growing perennials. And as Tom mentioned, perennials are absolutely the showstopper of the flower garden, and they work so well in landscapes. And we get so much mileage from our perennials. And of course, perennial flower is a flower that grows back each year and rewards us each year with blossoms. Some are longer lived than others. But again, the basic term perennial, a flower that comes back each year. Now, when you're talking about perennials, maybe reading about perennials, you'll notice the term dividing. Dividing a perennial. What do we mean by dividing a perennial? Well, perennial flowers tend to grow in clumps that each year increase in diameter a little bit. And dividing simply means to split that clump into more than one piece. So that's what we mean when a gardener says, I'm going to divide my perennials. Okay, well, why do we divide perennials? Okay, we mentioned that they come back each year. So why do we have to do anything with them? Why do we need to divide them? Well, there's a couple of good reasons to maintain vigor. If you take a look at the photo there of the clump of iris, it has become old. The old rhizomes in the center are no longer blooming well. It's less vigorous. So we want to maintain vigor by dividing occasionally. And also some perennials become so crowded. And by taking dividing, it gives them a whole new lease on life and no longer crowded. And to manage the size. Now some perennials such as the ground cover type of perennials spread outward and soon become just larger and more unruly than we would want. And so we can manage the size. And of course, one of the fun things about growing perennials is growing more of them. And so by dividing perennials, we can make more. We can increase the size of our perennial flower bed or share with friends and neighbors. And maybe we move. Maybe we want to move the perennial itself. Maybe it's in the wrong location. So we need to move it within the flower bed. Or maybe we ourselves are physically moving to another city. And we want to take great grandmother's peony along with us. So those are the reasons then why we would be digging, dividing, moving, relocating perennials. Okay. Well, how do we know if a perennial needs dividing or not? Well, one way to tell is to look at the center of the clump. If you take a look at this clump of ornamental grasses, notice how the center has died out. All the good parts are on the outer perimeter. So that is a clue to watch. And if ever the center, maybe it's a clump of iris, the ornamental grasses, maybe an old peony where all the good stuff is on the outside, the center is dead, it's time to divide. Or in the case of this daylily, it's just not blooming the way it used to because it's just become crowded. So if it's not blooming the way it used to, maybe time to dig and divide. Or take a look at this perennial sedum. Notice how the center instead of being nice and tight and full, it has splayed apart. And that's also a sign that that sedum has gotten old and would benefit from digging and divided. Okay, so when we're trying to decide if a perennial needs dividing, look for those key points. That'll help. But also, as a rule, certain perennials have a certain kind of a lifespan in which they should be divided. Okay, so I've divided these up into about four groups. You know, some need dividing more often, some hardly need dividing at all. And don't worry about trying to jot all these down because on the perennial handout that I provided to you, these are all listed there. So just sit back and enjoy and these are listed on the handout. Okay, so the first group are perennials that need dividing fairly often to keep them vigorous every one to three years. Maybe not every year, but maybe the third year. Okay, a few of the key ones in the list that you have the white chastidacy. About every three years or so, it's time to reset some nice fresh ones. The allium with the round pinkish lavender that needs rejuvenating every three years or so and iris. The tall German bearded iris, which is photographed there in the yellow. Every three years or so, they, the centers become a week and all the good stuff is on the outside. It's time to dig and divide them. Delphiniums are another one. The true lily that grows from a bulb, a hearty mums, those should almost be divided every year. So anyway, this is that group of one to three years fairly often. Okay, then the next group. And again, these are all on the handout. Every four to five years, such as the white flowered tall garden flocks, daylilies in the upper right hand corner. Daylilies every four to five years, bloom better if they're dug and divide. And we've got the galardias, coneflowers, ornamental grasses, which is pictured in the lower right hand. These are the mal grasses really every four to five years should be dug and a fresh clump from the outer perimeter, set back in. Okay, then next we progress to the group every six to 10 years or not very often, but they do benefit from about every 10 years at least that includes bleeding heart. Hosta, which is the blue, blue leaves up in the upper right hand corner. And perennial salvia has become quite popular that's in the lower left corner there, the orange poppies, Siberian iris, you know, and again, consult the list. Now, here's an interesting group. This is the group that rarely needs dividing, maybe every 10 years or more, maybe, maybe much longer and the reason that they don't need or want to be divided is they really don't like the root system monkey with that much included in that is the gas plant, which is in the upper left hand corner and actually on a calm summer night if you hold a match below those they do send up a little poof of flame, because they exude a gas I've I've done it I've seen it with my own eyes it actually works peonies peonies can stay in place a long, long, long time. Lupins don't like to have the roots monkey with roots are kind of brittle. The Russian sage milkweed the asclepias they have quite brittle roots they don't like to be dug and divided any more than absolutely necessary. So it's kind of nice to have a group of perennials like this that rarely need dividing. So again, we've grouped the perennials like that into time periods, your periods in which they'd like to be divided. Next thing you've probably heard that certain perennials want to be dug divided moved in the spring certain perennials want to be dug divided moved in the fall. Okay, how do you know which is which well there's a good rule of thumb, and that is do the operation during the season opposite when it's flowering. Okay, one of the easiest for me to remember is tulips okay tulips bloom in spring don't they, and the time to plant or if you're going to dig and rejuvenate tulip bed is in the fall. Now the reason for this is when a perennial is in full bloom. That's when it's at its weakest, it's expanded a lot of energy producing those beautiful flowers. And if we go digging and cutting the roots, that's really hard on a perennial and we could even lose it. So that is why we choose the season different from when it's blooming okay let's hone in on this a little little more closely. Okay, so if a perennial blooms in spring like the tulips spring early summer, then we dig and divide in the fall. Okay, say around Labor Day included in that group are the bleeding heart you know they bloom early, early summer spring, so do those in the fall. Peanuts, peanuts are blooming the end of May, early June, so we do those fall about Labor Day. Iris, anytime from about August on because iris typically bloom in June. Okay, so that's the group that we do in the in the fall. Okay, next, if it blooms in the fall or mid summer, then we dig divide move in the springtime. Think of Hosta, think of Hosta. When do they send up their flowers? That's always late summer and so we do those in springtime. Okay, how about ornamental grasses, when do they send up their seed head? Late summer fall, so we dig and divide in the spring, the season opposite of when they're blooming. Mums, the Hardy Garden Mums, classic example, mums bloom in the fall, we divide, dig, divide, move in the spring of the year. Okay, next we're going to take just a few examples of how we actually do dig these. Okay, here's an example of a Hosta. Okay, we mentioned that Hosta you dig, divide, move in the spring of the year. So just as a little bit of growth is starting, there's probably maybe first part of May or so depending on the year. I like to wait until you see a little tiny bit of growth, then you know that you're digging and dividing and getting a live clump. Okay, so here we are digging up that clump. Now, you wouldn't have to dig up the whole clump and divide. You could take away maybe three fourths and leave a fourth in place. But I like to dig up the whole clump because that helps get rid of any perennial weeds that are in the middle such as dandelions or little tree seedlings. You can get those out of there. And then also it gives you a chance maybe work some compost or peat moss in. So I prefer to dig up the entire clump there. Okay, then we break it apart. As a rule, I don't know a nice size clump of perennials. I can always get at least four chunks out of it. You could divide it up into more if you want. But the smaller division, it will take longer to regenerate and come back. Okay, that was one that we would do in spring just as it's starting growth like the Hosta. Okay, now let's take a look at digging and dividing something in the fall. Peonies. We mentioned peonies bloom in spring early summer. So we're digging, dividing, moving in the fall around Labor Day. All right, it's easier to work with them. If you do cut back the tops, just makes it easier to dig. Then we go ahead and dig up the clump. And what we get is a big massive. If you've ever dug up peony roots, it's it's a lot of work because there's there's a lot of them there. And I want you to focus specially on a couple of white spots there called the eyes. They're the buds. They are next year's buds, the stems that are going to come up where you see the arrow. Okay, we're going to focus on that. Now to divide these perennials, whether it was the Hosta or whether it's these peonies, an old gardener once showed me a method and I've used it ever since because it works so well. And that is to take the big clump of perennials and submerge it down in a wash tub, an old tote, a water tank, and you bounce it up and down in there and pretty soon the dirt will come away. And it will start to form some natural kind of divisions that you can pull apart. Now in the case of peonies, you oftentimes have to use a knife saw or a pruning shears also on those, but you're able to separate them out. In the case of a peony, it should each division should have maybe four or five of those good eyes, those whitish pink buds that you see there. Now with most perennials, when you reset a clump back in, just plant them at the same depth that you dug them up. There's usually kind of a little dirt layer or dirt line from which it came up and out. But peonies are very, very particular. The uppermost bud or eye on a peony needs to be situated so that it's no deeper than an inch and a half below soil surface. So that's why we have a kind of a stake across the top to gauge where the final product will be. Upper most bud no deeper than about an inch, inch and a half. Okay, and there we are pointing to those uppermost buds. Then of course, firm the soil in around and with any of these perennials, even the fall planted ones, very important to water them in thoroughly that will get good soil to root contact and will be good. Okay, a couple of quick notes on dividing iris. Okay, again, they bloom in June kind of towards the early part of summer, so we're digging dividing in September. You can also do in August. So we simply dig up the clump, you'll find a bunch of old rhizomes towards the center. Take the good parts from the outer spot. There you see me cutting back the foliage, cutting back the foliage in kind of a little bit of a fan shape that helps cut back the water loss. And you'll also notice that I've separated off with a knife, a good little clump and left behind the old part from the middle. Form a little hill of soil and then fan the true roots over that so that the rhizome is kind of resting on top. We don't want that too deep down into the soil or it'll rot and then backfill with soil. Now iris and most of these perennials do very well planted in a little grouping three, five, seven. You'll get a little more impact than just one. And of course, watermen very thoroughly after planting. Okay, the last one that we're going to take a look at is digging and dividing daylilies. Usually towards the end of summer, take a shovel, dig them up, we've cut the tops back, raise up that clump. And in a bucket of water, I like to submerge them. You could cut them with a knife, but also if you kind of pull and twist, it helps if you're doing it underwater, they will come apart in sections. Then you've got many, many sections you can replant. And again, plant them in a little grouping, you'll get a little more mileage, a grouping of one color. Then you really have impact. Now with our perennials, patience is the key. For example, a newly divided peony can take three to five years to come back into full blooming. That's okay. It's developing into something that'll last for many, many decades. So we need to have patience. The first year after digging and dividing with any perennial, the first growing season for sure, I remove all flower buds so that the strength can go down into the plant. The second year, I oftentimes will remove the flower buds to give the strength into the root system and developing a good hearty crown. And then by the third year, go ahead and enjoy. And with that, I will stop sharing my screen. I should mention first though, if you do have any questions or would like to email me, my email is donald.kinsler at ndsu.edu. Now I will stop sharing and I gladly entertain any questions. Okay, thank you, Don. That was an outstanding presentation. Okay, let's have your questions. Don, you talked a little bit about bleeding hearts. This person has a bleeding heart that's very big clump. Do you have anything more to say about that spring bloomer? Okay, bleeding heart don't require dividing very often. And even though it's a big clump, if the center is still healthy and not dead in the center, then you can let it go as long as you want as long as it's still blooming prolifically. Beautiful shade type perennial or half day sun, morning sun, rest of the day shade. So as long as it remains healthy, there's not an urgent need to divide it. How about perennial geranium? Perennial geranium, wonderful. I wish it had a different name because we all get confused with the geranium that we put in planters. But the perennial geranium is a beautiful kind of lavender. I think there's some whitish, pinkish blossoms too. A nice mound shape. The perennial geranium is in the group that probably would like to be divided every, oh, probably three to five years or so to keep them vigorous. A nice perennial, nice mound shaped perennial. This person's got a clump of grass. It's so thick that they can't even get a shovel into it. I believe that. So what do we do about it? Well, one thing a person can do when you've got, yeah, and some of those just become such a massive roots that it's hard to get a shovel down in. Okay, when it's still in place, you can try to physically force the shovel, the spading type shovel down in between, or sometimes if that doesn't work, I will take an old saw and physically cut down through those crowns and then that makes digging easier as well. Okay, great. This person has a large Russian sage that needs some division. How much of a plant do we need to get a new one started? Like when we divide them up, how much do we need like a certain amount of that sage to remain? Yeah, well, theoretically, you can divide most perennials into just a little kind of a stem with a little bit of a growing point. But if I was going to give you a measurement, I would say a clump of perennials that you're going to reset should probably be, I don't know, maybe six inches diameter. So on a Russian sage, when you dig it up, I'd prefer to be replanting something that is at least about six inches. Then you'll have enough roots and enough stem to come back with vigor. Sounds good. How about lady slippers, Don? Ah, lady slippers. You know, on my bucket list is to grow everything that we can grow in these parts. And I've got a long way to go because I have not grown lady slippers. Lady slippers are, and again, experience is the best teacher. So I'm going to have to speak from book learning instead of experience on this. But lady slippers do tend to be a little difficult to transplant, I am told. And so if you can just leave them alone, they're probably better off once you get them established. Yeah, that's what I've heard too, Don. How about hydrangeas? Any tips on hydrangeas? Ah, hydrangea. It depends on the type of hydrangea. The type of hydrangea that kind of acts a little bit like a perennial flower is the anabelle type with the large white flowers, because they die back to near ground level or maybe six inches above approximately. And so each spring you cut them all the way back. I like to wait until you see where the growth has started, but cut it back, you know, six inches above ground level or so. And then it comes back almost like perennials do from the lower part. And so the anabelle type does want to be cut back. The other type, the penicillata type, which are the pyramidal, those are more like what I call a normal shrub. You don't cut those all the way back. Speaking of cutting back, getting back to that ornamental grass, when you divide it, how low do you cut back that ornamental grass? One inch above ground level. If you leave too much, you get like a hay field, an old stubble field. And so yeah, cut as much of that, because the new growth comes from down in the crown and there's no need to have more than about an inch. And they are better cut back in the spring. Leave the tops intact over winter. Thank you. Donna, I don't know about dividing, but with Clematis, do you have any advice on when to move a Clematis plant? Yeah, Clematis would be best moved in spring, just as you're starting to see a little bit of shoot coming up. So I suppose we're talking maybe 1st of May, maybe late April. But I like to wait until you see a little sprout coming because then you know you're getting a life chunk. And Clematis takes 3, 4, 5 years from the time you either plant a new one or divide one until you get a really good, robust vine again. But you'll get them in the springtime just as you're starting growth. Donna, as far as perennials, for those of us who aren't as experienced as you are, do you have a good resource about where we can, like if we have perennials in our garden, like how do we identify it? I think that's a good resource. Wow. One excellent resource, not necessarily for identifying, but at the bottom of your handout from our sister university, University of Minnesota, they have a wonderful spreadsheet that tells all of the perennials and when to divide. It's kind of a spreadsheet, tells kind of when they blew them, when to divide, how often to divide. And they also, from University of Minnesota Press, there is a very good book, I may not get the title correct, but if you Google University of Minnesota Press, Perennials for Northern Gardens, I believe it's called. Good. How about, you know, you talked about, you said like, you like to dig out the entire plant when you divide something. And that gives you the opportunity for adding some compost, and do you ever add any like a chemical fertilizer, like in particular phosphorus to promote rooting or flowering? A person could, and of course that's a, there's a good point to promote soil testing, to see what the nutrition of the soil is, of course. And, but perennials do respond very well to fertilizer. You know, they will, what you give them in the way of nutrition will reward you with extra blossoms. So, again, if you're low in any of those, those nutrients through soil tests, then definitely steer for toward that nutrient. But also, if the soil tests average, I like to give 10, 10, 10. If it requires that 10, 10, 10 granular in the spring. A water soluble type poured on in the spring works quite well also. Perennials love organic matter. And so anytime you can work a little organic matter in compost that has a light of a nutrient source also. Well-aged, clean manure works well as well. Perennials love to be mulched. It keeps the soil with a natural type mulch, not rock mulch. It keeps the soil nice and cool and fresh also. Okay, done. This person has a yellow quill mammoth mom. It's only one year old. And when's the next time it should be divided? I love the mammoth moms. They were developed by University of Minnesota. One of the hardier garden moms. They really should be, they should be dug and divided each spring is the recommended. Because they tend to die out kind of in the center and you'll get a little cluster of new growth around the edges. So, and they are definitely winter tender. The top should be left on over winter to catch a little snow, a little extra leaves. And in the spring of the year in May, when you start seeing new little tufts growing from the outer perimeter, then dig and reset. And they should bloom for you in the fall. Okay. Okay, Don, you talk about, I'm going to divide my spring bloomers in fall and my fall bloomers in spring. Okay, what do we do about that summertime? Like in July, this person has an allium that says blooms in July. When do we divide that? Yeah, good. Now good question. The things that are kind of in the middle of summer blooming, generally you'd move those to the spring, like allium or spring, spring divided. So just as they're starting up some little shoots in the spring then divide garden flocks blooms kind of in the heart of the summer, they're also spring. So if it's kind of in that middle of summer, then spring works well. So those days are kind of towards the last half of summer. And so those are, those daylilies are so flexible you can do anytime. Right, almost a weekend. More things are divided in spring than in fall. You know, in fall you got the P&E's, bleeding hearts, iris, tulips. I think you made the good point, Don, is about just make sure it's not blooming when it's most vulnerable. Really, right? Yep, the time not to move great grandmother's P&E is in late May when it's blooming. There you go. This person's got a lupine and it's not coming up after the first year. Lupins are tricky. I've had a hard time getting them established. A soil very rich and organic material, you know, so amend the soil probably in an 18 to 24 inch circle. They love the organics like peat moss and well rotted compost and give them time. Lupins are a challenge. Okay, Don, here we go. You mentioned the anabelle hydrangea. Now is an incredible hydrangea the same as an anabelle hydrangea? The incredible is a cultivar of that type. It's the hydrangea arborescence is the species of those, which includes the anabelle, the incredible, and I believe invincible spirit is another of that. So there seems to be... Yeah, basically they're the big rounded blossoms rather than pure middle big rounded blossoms. Okay, let me see. I think I saw a question about come across on ornamental grasses, a really good ornamental grass that doesn't spread. One of my favorites is the Korean feather reed grass. Korean feather reed grass. I've seen it at local garden centers. I've had it for about three years. It's beautiful. How is that different than the Carl Forster feather reed grass? Well, Carl Forster is quite upright and produces a little seed stocks up above. The Korean feather reed grass becomes a little wider, a little wider out, not quite so soldier like. And it's got a looser panicle, seed panicle, and I just find it a little more attractive. Maybe it's because I've gotten tired of all the Carl Forster around the dentist's office and banks in town. But they are beautiful in the right place as well. Right. Dan, how about do you cut off the tops of your hostas? Even the blue? Yeah, most perennials benefit from having their tops, their above ground portion left on over winter. Hosta are an exception as are peonies and iras. They plop apart over winter and get so mushy. So, hosta, I think, are best cut back right after a frost while you're still manageable. The flower, you mentioned the flowers. Some flowers on hosta are quite pretty and add to them. The type of hosta I have, the flowers actually detract from them. So, when the flower stocks start, I actually cut them back so that the beautiful foliage of the hosta shows better. How about a rose bush, Dan? Can I divide my rose bushes? Well, that's a woody plant. Most rose bushes, not all, but most are from a single crown that does not divide well. There are a few types of roses that do send up some sucker shoots around and those could be divided. Right. The plants we're talking about tonight are herbaceous. They're not woody plants. That's the key difference, right? Let's see here. Will frost kill tulip bulbs? Tulips are frost-hardy, winter-hardy, and so they actually do need a winter chill in order to come back up. Tulips can be grown beautifully in the North Country. Right. How about dividing little blue stem or big blue stem grasses? They grow beautifully and, of course, a native. And in the spring of the year, just as a little bit of growth is starting, that would be the time to divide. They can stay in place until the center starts becoming empty. As far as ornamental grasses, you cut them every spring. You never burned them? You ever thought about doing that? Well, they could be burned, but I'm afraid our neighborhood would probably frown. Our authorities, I believe, would frown on it. But, of course, that would be nature's way of getting rid of all the old fluff. But in lieu of burning, then cutting way back to an inch above gets rid of the old fluff. Okay. Don, I think you got it all covered here. That was a great presentation. Thanks for starting with us. Yeah, I want to thank everyone. And enjoy your perennials. Thank you very much.