After an abnormally long, cold spring, it’s finally starting to warm up in Minnesota. That means it’s time to start working on your spring garden.
MPR News host Angela Davis talks with two master gardeners about their tips for what to plant this spring, how to manage your lawn and how to plant a climate-resilient garden.
Julie Weisenhorn is an extension educator and associate extension professor in the University of Minnesota’s department of horticultural science.
Catherine Grant is a horticulturalist and greenhouse manager in the Department of Biology at the University of St. Thomas.
The following is a collection of answers to audience questions, edited for clarity and brevity. Listen to the full conversation by using the audio player above.
To start us off, can you tell us about “No Mow May?”
Catherine Grant: “No Mow May” is a is a nice marketing term. It came out of the UK, I think a nonprofit called Plant Life started this in the UK a few years back, where they encouraged people to not mow their lawns for the month of May because the month of May generally corresponds to the emergence of the bees that have overwintered are coming out of hibernation.
When they come out in early spring, there's not many things that are blooming to give them the pollen and the nectar they need both the nurse themselves on to start a new round of babies, basically. And so a lot of us have in our lawns if we don't have you have a perfectly manicured lawn that is only Kentucky Bluegrass, this doesn't really apply to you. But if you've got dandelions, violets, self-heal and clover in your lawn, you want to give it a chance to bloom. And you don't want to kick that lawnmower out right when it's starting to bloom, and mow down all the all of the flowers that are there because the bees will come out and they won't be there for them.
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That is very tragic!
Grant: It is tragic and it is damaging. So we want to increase the amount of forage there are for early spring bees. And you can do that in multiple ways. But most of us have lawns, and if you have flowers growing in your lawn, please for the month of May, just ignore the itch to get your lawnmower out. I’m ignoring the itch myself right now, because I can see a lumpy lawn out there with things growing in it.
Let flowers bloom and provide habitat for the early emerging bees and also just go try to sit down and calm yourself (laughter) and notice that there are bees that are flying to an fro amongst those things that you think are weeds and a sign of bad homeownership. It’s actually that you’re providing habitat for them.
Julie Weisenhorn: In Minnesota, idealy we’d like to have something blooming in our yard from April through October to provide, as Catherine mentioned, nutrition for early emerging bees. The problem is we don’t have a lot of flowers that bloom, but we can have a lot of wildflowers, but a lot of people don’t have tons of those. But you know, we have a lot of lawn. And by leaving that and allowing these plants to bloom in your lawn, you’re adding to that food source for these early bees.
The other thing about mowing is let your grass grow this time of year it really gets going. We have cool season grasses in Minnesota. And… when we have a better root to shoot ratio, in other words, we have longer blads, we produce longer roots in our grasses, and that will help the grass survive those really tough dry hot Julys that we get. So leaving your grass longer, you know when you do go to mow it after No Mow May, then raise your mower to about three, three and a half inches so that you have longer blades and you’ll have a much healthier lawn. You’ll be able to use fewer pesticides, and it’ll shade the weeds out, and you’ll just have a healthier, thicker lawn overall.
I mentioned this earlier, but leave the leaves, what do we need to know about the role that leaves are playing?
Grant: So leaves fall from trees and they fall on our gardens and our lawns and our hardscapes. It’s perfectly acceptable to get them off your hardscape and off your lawn. But where they really belong is in your beds. Leaves to me are free fertilizer and free mulch. When leaves decompose in your beds, they’re feeding a whole bunch of invertebrates and bacteria and fungi and things that live in the soil. And they transform the leaf into nutrients that are now available for your plants. So instead of going out and buying fertilizers at the garden store, leave your leaves on your beds.
A lot of people think they look messy and they also get itchy rake fingers, like they want to go rake all othse leaves out this time of year. I’ve been doing this for over 20 years, where you leave them in, you bite your fingernails and you wait. As soon as your garden starts growing in and the leaves knit together, you don’t see the leaves anymore. They eventually disappear because they decompose.
Also, this is a little weird, but at night if you go out in a yard that has a nice mulch of leaves in the beds, you can hear the earthworms coming up and eating them. I know that sounds weird, but everyone who has leaves, do it. It will freak you out a little bit, but it’s pretty interesting.
What you’re doing is you’re providing foods. So again, like taking away the flowers in your lawn before the bees can get to them — if you take the leaves away, you’re taking away a food source for all the microorganisms and the invertebrates that live in your soil and keep your soil healthy for your plants.
Mary Joe from Longfellow, Minneapolis: I have a small yard but it’s a corner lot, and my dog is sort of the unofficial mayor of the blocks in Longfellow. So all these dogs come over and it’s sort of an informal dog park. My grass has not survived it very well. But I have clover and variegated violets and this sort of short-lived weed that have sort of filled in the lawn. I’m wondering if I should rake those clumps of dirt and seed it with clover or is there another, like a bee lawn feed? What would you suggest?
Weisenhorn: Good for you for having dog parties, that’s awesome. And being realistic about your lawn! A lot of people with dogs say “what can I do to eliminate these brown spots from the dogs peeing on there, and there really isn’t anything to do except rake it up and reseed it. I like that you have a mixture of plants in your lawn.
I like your idea to use clover or you can use a bee lawn mix, that bee lawn mix is actually quite high in grasses, mostly fine fescues which is a tough turf grass, and a bit of Kentucky bluegrass. But then also perennial flowers like white dutch clover, self-heal, ground plum and creeping thyme. These four flowers bloom at different times of the season, and they are appreciated by different kinds of bees. That’s a great thing to use in your yard.
It’s also a pretty good ground cover. I’m not sure it would endure like great racing dogs and things like that, but it’s a great thing to do. Raking up those spots, getting rid of some of that dead grass that you see, and then seeding it would be a good thing to do. You might want to put some small fencing around some of the larger spots just to keep the dogs out of there, and be sure to water it so that those seeds stay hydrated. You want good seed to soil contact too, so rake up that soil, you can mix a little topsoil in with your seed and just spread it out there and keep it watered.
Catherine from Minneapolis: After last summer with the drought and the heat creeping charlie kind of took over the entire backyard. But I'm wondering if the creeping charlie — eventually as the season wears on — will actually be detrimental to choking out as I see it, wrap around the ferns or wrap around other things in the yard? Is there a way to balance the creeping charlie and try to get grass back? Or do I just try to maintain creeping charlie?
Grant: Creeping charlie is a problem. It’s an aggressive weed that creeps along in the ground. Which is why it’s called creeping charlie. It will go into your beds, it will go everywhere you allow it to go, so it’s up to you to decide how much effort you want to put into controlling it and containing it. But its modus operandi is to expand and go anywhere it possibly could go.
The ways to get rid of it or try to contain it is you and a trowel and digging it up by the roots. Another way is to try and smother it with something else that’s gonna grow as fast or faster than it. But that’s a very tough battle.
I’ve known people to decide to get rid of the creeping charlie and the best way, honestly, is to put down black plastic or something and smother it and kill it, and once you’ve done that, you plant something else in it. But you’re always going to have to pay attention to find it and kill it because it’s just going to keep coming back.
Weisenhorn: Creeping charlie, as Catherine mentioned, is a perennial weed. It’s in the mint family, which if anybody’s had mint take over, they know what I’m talking about. And it’s not a very beneficial pollinator plant. We did some research. James Wolfen, who was a graduate student in our entomology department, took a look at the flowers of creeping charlie, and found that the nectar they provide is pretty marginal and pretty spotty. So we’ve seen a lot of bees on the flowers because there are a lot of flowers on creeping charlie, but the pollen rewards are pretty lame, so are the nectar rewards.
There is the option of chemicals, and I hate to bring that up because a lot of people don’t want to use those. But a combination of glyphosate and triclopyr would be one option for really, really invested areas. But you have to be careful with that because it will kill everything it touches. So it’s really just for large patches that you are going to kill off and then promptly reseed.
But when it gets into your garden, Catherine’s right, it takes a trowel, dig it up, keep working on it. I also recommend when you have invasive plants like that is that you pick your battles. You choose the areas that you’re going to really eradicate. If you have a large yard, it can be very overwhelming. So say “I’m going to worry about it up to this point, and after that, I’m going to not worry so much about it.” Or I might use a longer term control, like Catherine mentioned, like a smothering where you can cover it with leaves or plastic or something like that, but that takes a long time.
Eva in St. Michael: I can’t get to my front garden because I’ve invited ground hornets. I can’t do anything. I bought dust powder, but I don’t know where the enterences are, and I can’t tell how many because they’re in the mulch. So I’m going to have to powder the entire thing? Or, I was thinking, can I cover it with clear plastic so they can’t get out? What can I do? I don’t want to dig up the entire bed and then get stung. What do I do?
Grant: I think the first thing you want to do is get a professional to ID them to make sure that is what you’re dealing with. Because it could be — I mean, maybe you do know that they are hornets, which sting and aren’t very nice to have around. But it could also be just a ground dwelling bee, which you want to encourage them to be there. I would say find a reputable pest control company and have them positively ID what you have, and then take it from there in terms of the best methods of control.
Karen in Minneapolis: Last year Japanese beetle larvae destroyed our front lawn, like a lot of people in the neighborhood. I'm wondering what I can plant there that won't be similarly destroyed going forward?
Weisenhorn: So Japanese beetle grubs at this time of year are very large, they’re at their mature size and they’re just about ready to pupate into adults. And treatments for grubs is actually around July. This is because right now the grubs are so large that treating them is very difficult. Once the adults emerge, these new adults, they go in and they lay their eggs, and those hatch out into small larvae, and those are easier to control. So treatment is in the middle of the summer.
You’re asking about what to plant that they won’t feed on, it’s going to be something other than grass. So it’s going to be shrubs. You might try a different type of ground cover as well. We have a good webpage on that for extension, you can see a variety of those on our yard and garden page.
It depends on what you want to do in that space. If it’s active, if it’s a play area, for example, really grass is all you can put down. Then you would have to treat your lawn for grubs. The other options, if it’s an area that’s maybe less used, a side yard or something, you could do ground covers, like pachysandra, which is not a really walkable ground cover. But something that would certainly cover the ground and does well in shady areas.