Spring starts Thursday and many Coloradans are eager to dig into their gardens. But in a state where late frosts and hailstorms can derail even the best-laid planting plans, when is the right time to start? And how can gardeners protect their plants from unpredictable weather and pests?
To answer these questions, Colorado Matters senior host Ryan Warner visited Phelan Gardens in Colorado Springs, where he spoke with Sam Nilsson, the head grower at the nursery. Pueblo resident Kathy Bell joined them at the greenhouse with her own gardening questions. Together, they discussed best practices for spring planting, sustainable alternatives to traditional lawns, and how to handle common gardening challenges.
This interview has been edited for length and clarity
What if you give in to your impatience and plant early?
Ryan Warner: I love this sign. "These plants are not ready for sale as they are still rooting. Thank you for your patience." Do you have to have a lot of patience right now?
Sam Nilsson: Yes. A lot of patience. People are eager to garden. They want to buy stuff already and it's too cold to plant and things are not ready to be sold.
Warner: It's too cold to plant. Okay. This makes me think of the old saw in Colorado: Don’t plant before Mother’s Day. Do you think that’s generally true?
Nilsson: In general? Yes. We recommend Mother’s Day. That’s our average last frost. So annuals and vegetables, especially after Mother’s Day. Perennials, trees, and shrubs? You can do a little bit before, but usually Mother's Day. Annuals and vegetables are not cold-hardy here, and so if you put them outside and we get a frost or we get a snow, they are most likely going to just die and you’re going to start over.
How clean should my yard be?
Listener Kathy Bell: I want to know about what I perceive as a new ethos in our yards in suburbia. How clean is a yard now supposed to be? I’m used to kind of beautiful and sterile yards, but I am seeing and reading about our pollinators and our little critters that need leaf mulch and they need a messier yard. So are you finding that people are not cleaning up quite as they did in the past, and are you advocating that?
Nilsson: Great question. Yes, we do advocate for that, which is kind of hard to convince people to do sometimes. Our pollinators tend to hibernate in the stems of our woody perennials that don’t fully die back, so doing any of your cutting back in the springtime is recommended so those guys can overwinter and then come out. Same with the leaf matter on the ground or any organic matter on the ground. A lot of things hibernate and need that extra layer of mulch to make it through the winter. We try to encourage people to not clean up until the spring when it’s been at least 50 degrees for a week straight and all those guys can kind of wake up and get out.
How to protect your garden from hail
Warner: It can be fraught to garden in Colorado. Sam, what do you say to folks who have a fear of hail? It’s our costliest natural disaster.
Nilsson: With hail, we really try to push hail cloth a lot. It’s not the prettiest thing in the world, but especially when you’re doing vegetable gardening and you mentioned the cost of things, you can lose your whole garden with one bad hailstorm, and so investing in something like hail cloth is really helpful. It doesn’t block the sunlight, it just stays over. You can leave it up or take it down.
It's kind of a mesh type fabric, but it's a thicker plastic mesh, and so a lot of people will do PVC hoops over their garden that you can lay it across, and as long as the hail hits that rather than your plants, it will absorb the shock from the hail. Even here, we don't have the structures, but we lay hail cloth over the plants if we have a storm coming, and that alone makes a huge difference.
From grass to clover
Warner: Steve Livingston wants to transition his lawn from grass to clover. This is presumably to make it more sustainable. What do you think of this idea?
Nilsson: I think it's a great idea. I wish everybody would have a clover lawn. It’s more drought-tolerant. It is pollinator-friendly. Those are the biggest reasons. It's a lot less maintenance as well than your lawn. It doesn't need to be mowed as often.
It's still a great option if you have kids or dogs. It's a perennial, so it comes back just like your grass does. They get the cute little white flowers that the bees love, but nobody has issues with the bees. People get concerned that they're going to have all these bees and their kids are going to get stung by bees and that it doesn't seem to be an issue.
To begin, you want to mow your grass down as low as you can, thatch it, get any leftover dying grass out, and just get as best contact with the soil as you can get for those seeds. If you need to aerate your lawn, you can do that. If you're taking good care of it, you might not need to aerate it, but it wouldn't hurt. You can seed in the spring, early spring, so it germinates before the heat of the summer. Or you can also do it in the fall and the roots will establish well enough to stay dormant over the winter and then come up in the spring. That's also an option.
The best perennial variety here is Dutch white clover. There's also a microclover. The research I've done, they're very similar, but Dutch white clover is what we get and it works really well. It’s actually one of our less expensive seeds, but the nice thing about clover is it reseeds and spreads itself out. You don't have to mow it, but we do tell people, especially with those larger properties, that if you do mow it for a while, that will help it spread as well. But it essentially will take over your lawn and you can seed over it.
Alternatives to junipers
Warner: In Broomfield, Laurel Witt and her husband removed juniper brushes to reduce wildfire risk, and now they're wondering about some evergreen alternatives.
Nilsson: Dogwood Ninebark Elderberry, Barberry Sumac is a good option. Lilac and Viburnum were some of their top recommendations for non-evergreen options to have in your yard. Other good evergreen options to replace your junipers with would be Boxwoods, Kinnikinnick (Manzanita), Holly, and a Globe Blue Spruce.
How to deal with pests
Warner: Fae McLaughlin wants to know how to deal with pests on her houseplants, in particular, and Joyce Honour hopes to control grasshoppers. They want to know if there are natural suggestions so they're not poisoning themselves and others.
Nilsson: Houseplants can get quite a few different types of pests, but typically they'll come if your plants are sending out a stress signal. So the best way is to evaluate how you're caring for your plants. Light and water-wise is a good step, but if you wanted to use a spray of sorts, isopropyl alcohol actually works really well for a lot of pests on houseplants. If they wanted to purchase a true pesticide, I would recommend something like Spinosad Soap or horticultural oil. Some pests have a harder body and you have to use that oil to really be effective on them, but isopropyl alcohol does the same thing, so a lot of people will use that.
Warner: I love this idea though, to get to the root, if you will, of the problem because the pests themselves are attracted to the feebleness of a particular plant. So ask yourself, is it healthy? And would that be a question of soil, of light or of water?
Nilsson: All of the above. Certain pests, like spider mites for example, are attracted to plants that are going too dry in between watering. So if you're seeing that on your plants, it's good to look at how often you're watering or if you're not having enough humidity, maybe it could also be a root issue. If you're overwatering and things are starting to rot and you're maybe just not seeing that on the plant yet, that plant can still send out a stress signal that will attract those pests to it just to make it worse.
Warner: What about grasshoppers?
Nilsson: Oh, grasshoppers. They're a pain. The biggest thing that people can do for grasshoppers is to till their soil, grasshoppers lay their eggs in undisturbed soil. And so even if you're working your garden bed all the time, and you might not think that's undisturbed, but you have this whole yard sitting right next to it that you're just mowing and not ever aerating or tilling, grasshoppers are going to lay their eggs there and they're going to emerge themselves in the spring and start reproducing, and it's going to just happen again. So tilling and aerating your soil regularly? At least regularly. Well, at least in the springtime. I've already seen grasshoppers coming out in my yard, so I would say a week or two earlier than this weather we're having would've been a good time to start tilling my yard and messing up those eggs and disturbing that soil. But it's never too late to till.
Warner: Any suggestions for aphids?
Nilsson: Ladybugs. That is a really great option, especially if you're trying to go natural. What I have learned about ladybugs recently is a lot of times we think that the adults are really munching on these aphids, and while they are, it's important to get them in there so they can start their life cycle. The larvae eat the most aphids to grow, and so getting 'em in maybe before you're even seeing a problem and getting them in your yard so they can start laying eggs, that would help a lot.
And I encourage everybody to look up a picture of a baby ladybug because they do not look anything like you would think they look like, and people want to kill them, and they think they're bad, but they're really good. So look up a picture. I think they're really cute, but they don't look like ladybugs at all. So people bring 'em in all the time. They're like, “What is this? How do I get rid of it?” But you want 'em around.
The best plants and soil for your raised garden beds
Warner: Two related questions from Diane Green and Natalie Nowak. This is about raised garden beds. One, what are the best herbs and veggies to plant in a small space?
Nilsson: Any determinant-style tomato that gets to a certain height would be a good option. Your determinants have a set mature height that they'll get to. Whereas the indeterminates – those are the ones you want to prune a little bit more and keep a little closer eye on. But they produce a lot of tomatoes, so some people like either or, but determinants would be good for a smaller space. They'll stay just a little bit more in their own space. Any herb really will do well in a raised bed setting. As long as you have enough sun, you can do some smaller-bodied peppers as well. Their plants tend to stay a little smaller. In general. They don't need to support the weight of those big peppers.
A lot of spicier ones are going to stay smaller, so I don't know how people feel about that, but Thai chilies are a really good option. They're a long, skinny, lightweight pepper. Habaneros. We get some mini bell peppers in. Those would be good options.
Warner: And then a second question on the raised beds. How do you amend the soil in them? Asks Natalie Nowak, should you use worm castings, compost, something else?
Nilsson: Compost is a great option. That's what we typically will recommend. You want to get that organic matter back into your soil. Pretty much each season, the plants and water and everything just kind of clears out the nutrients. The only thing is if it's an edible garden, you grow vegetables and herbs in it. I just wouldn't recommend using a manure-based compost for a garden bed that you're putting your seedlings into because it can tend to burn the seedlings. It just has so many nutrients in it that they're not used to yet, and so you just have to be careful with that. But compost is the best.
What to look for if you want your own greenhouse
Warner: A question from Nadine Duesker-Pratt in Colorado Springs. She'd like to buy a small greenhouse, but she's worried about hail. We talked about that a little earlier. So hail cloth, maybe a suggestion for her. She's also thinking about the high-altitude sun exposure, the wind and the potential freezing temperatures.
Nilsson: If she's going to build a greenhouse, I would recommend using a polycarbonate material rather than a polyplastic material. It's still plastic, but it's just a lot thicker. It can withstand the hail a lot better versus we sell poly plastic and that if we get a bad enough hail storm, it can penetrate that plastic. So a polycarbonate is going to be a really good option. With regards to the temperature, I always recommend people have temperature-controlled greenhouses. I see a lot of people come in that don't have that, and it gets way too hot in the summer for anything to survive and way too cold in the winter for anything to survive.
A lot of people are getting Costco greenhouses, which are so cute. They're a great size. They work really well, but they're not temperature-controlled. If you go through like a local business, there are a couple people in town that have greenhouse building businesses, and I'm pretty sure you can add them in as an accessory as they're building them, some sort of ventilation, some sort of heating. You can even get power to them if you do it that way.
How to prune roses
Warner: Let's jump the continental divide on the western slope. Barbara Gallagher says she's confused. She's new to rose gardening and wants to know when to cut them back.
Nilsson: Roses can be a little tricky depending on the variety. There are so many to choose from. They like to be pruned. Early spring, late winter time is when we would recommend doing that. Even if they're already budding, she can still prune them. Roses have some sets of five leaves and sets of three leaves, and you want to cut back to the set of five, the newest set of five leaves, even if that means you're going past sets of three.
Fruit trees at elevation and other fruit-related questions
Warner: A question from Mike Lyons in the foothills above Boulder. Can you recommend a fruit tree to him that can handle living at 7,500 feet? And Mike wants to know when to plant it, if so.
Nilsson: We have a couple of fruit trees that we would recommend, one of which is a Contender Peach that does not require a pollinator. A Mount Royal Plum, which also does not require a pollinator. And you could also do a Honey Crisp Apple, but you would want to get a pollinator for that. And we would recommend something like a Macintosh Apple. As far as planting goes, as long as he's getting these trees from somewhere that keeps their trees outside year-round, he can plant it as long as his ground is not frozen, they're already used to the temperature and wind and everything.
Warner: Gwynne Hollis has another food-related question. She has a three-year-old blackberry bush that flowers and has pollinators around it, but no other critters. It only produces about three blackberries, and she says it flowers, but hardly fruits. What's Gwen doing wrong?
Nilsson: I would be curious to see where she has it planted. Blackberries do need full sun, which is at least six hours of direct sun on it. They need moderate watering once established. So I would also be curious about her watering. But the biggest thing with blackberries is fertilizing. Any of your edibles are going to be really heavy feeders in Colorado. So fertilizing was something higher in phosphorus. Phosphorus helps with any of your fruit production. Flowering production. So fertilizing would be something to try and help encourage those blackberries to grow.
Gardening in small spaces
Warner: A question from Lana Graham: She has no land to garden in. What kind of produce does well in container gardens?
Nilsson: The biggest thing with container gardening is one, making sure you have enough sun that six hours of direct sun all produce pretty much is going to want that. And then depending on what you're doing, you want a big enough container. So patio tomatoes are a really great container option, but you'd want at least a five-gallon container. Anything smaller is not going to do too well for you. Strawberries can do really well in a container. That can be a little bit smaller. You can even do 'em in a hanging basket. The small-bodied peppers, again, we kind of talked about earlier, those would do well in a container. Any herb really will do well in a container. And then also blueberries. We actually always recommend planting blueberries in a container here because the soil just, they don't like our soil. So blueberries do really well in a container.
The trick to mixing compost
Listener Kathy Bell: When you are cleaning up your yard, instead of sending everything to the dump, how do you break it down very quickly so that you can use it as compost in your yard?
Nilsson: The biggest thing with compost is making sure you have your green and brown matter mixed together and keeping it watered. Earthworms. Making sure you have a good supply of worms in your compost bin, that also helps it break down a lot quicker.
Bell: I have two compost containers. One is what you're talking about, which is great for kitchen scraps, but I have another huge pile with twigs and leaves and grass. I mean, it's big and it doesn't seem to be breaking down very quickly at all. And I haven't dug into it, so I don't know. I'm going to guess there aren't that many because it's been sitting there for quite a while.
Nilsson: And maybe since you haven't dug into it, it might be good to turn it to and till it and make sure you're getting all that stuff still on top kind of underneath, and that good stuff back on top that keeps it moist and warm. And then seeing how many worms you've got going in there and maybe adding some more.
Editor's note: Phelan Gardens is a sponsor of KRCC but has no editorial influence.
