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Expert Offers Winter Gardening Tips

Expert Offers Winter Gardening Tips; Submit Your Questions
Nan will answer your questions in the comments section below from 1-2 p.m. Submit your questions and hit "refresh" to see Nan's answers.

CAVANAUGH: This is KPBS Midday Edition. I'm Maureen Cavanaugh. This is the season that separates San Diego gardens from most in the country. Instead of being covered in snow and ice, our gardens are active, and gardeners still have lots of questions about harvesting the browny of the late fall and cleaning it up. My divest, Nan Sterman, and here with these answers. Nan is designer and author of California gardener's volume two, and water-plants for the southwest. She writes a garden column for the San Diego Union Tribune. Welcome to the show. We invite our listeners to join the conversation. You can call us with your gardening questions at 1-888-895-5727. Or you can join Nan Sterman for a live chat right after the show, log into Now, what are you doing in the garden right now? STERMAN: I'm having so much fun in my garden right now. People think it's winter it's cold, no gardening. I am just out there cleaning up. Plants have gotten ratty looking or overgrown, I'm out there cutting away. And it's really therapeutic for me. CAVANAUGH: Why so? STERMAN: There's something about pruning and cleaning and renewal. When I get done, I stand back and go Omy God, look at that. It's like when you clean your closet, you know? It's like a new start. And the thing is, what's different from cleaning your closets, come springtime, all these plants are going to burst out in new foliage, and I know I did that. CAVANAUGH: When do you know when it's time to cut back a plant? There's different categories. The -- the plants I'm talking about are ornamental glasses that have turned brown. Their silhouettes are would you feel, but a lot of them, I've not cut them back for a couple of years. And I just need to give them a haircut so the fresh new growth can come out. There are some perennials like the salvias that will grow and grow, and underneath the undergrowth is dead, but the top growth is green. So I don't want to cut the under part because I have to cut the top too. But if I put them all back, in the spring, they all come back. That doesn't apply to every plant, but for those kinds of plants, you can do that. CAVANAUGH: What about prune something STERMAN: Ooh! I got my electric chainsaw. You could see me with the goggles. CAVANAUGH: I'm afraid of you already! STERMAN: And so are the plants. I feel them shaking when I go out there. All of the deciduous fruit trees are the trees that lose their leaves in the winter. Apples, pears, peaches, nectarines, they all need a pruning to produce better in the spring. So I have 30 or 40 different trees and shrubs and grapevines that I go through sequentially because I can't do them all at once. I prune them, cut out the dead wood, the old wood, I cut back the branches, and suddenly sometimes you'll see there's a branch that wasn't there, and then it's there. And it goes straight up. We don't want that. Prune those back. And I'm careful about when I cut because all those plants produce fruit on different wood. Some of them make little fruiting spurs, short branches that come off. So you have to know what you're cutting off otherwise you can cut off the wrong part and get no fruit the nextier. CAVANAUGH: Oh, wow. STERMAN: I have a book, my favorite book is this little book from the 40s called how to prune fruit trees. And it's by either R. Sanford Martin or R. Martin Sanford or something like that. And I know that Walter nurseries carries this book. It's just the right size. Mine is completely dog-eared and beat up. But I need it with me so I don't cut the wrong thing off. CAVANAUGH: We are taking your calls. You can join Nan Sterman for a live chat after the show. &%F0 You do garden editing when you're doing this cleanup in your garden. What do you mean by that? STERMAN: This is a great term that I love am we you will want to plant. And sometimes your garden does better if you stand back and look at it and say what doesn't fit? What's not working? What maybe is larger than I can fit? And editing is actually taking things away, and creating new opportunities and spaces. It's almost like less as more. There's a point at which it's not, but you have to stop and look and say what can I take out to improve this particular garden bed? A lot of people will plant some things, especially designers, they'll design some plants that are supposed to be long-lived, but supplement with things that are short lived so you still have a full look. A lot of people don't realize that's what they've done. And they don't know they need to go back and take this particular whatever it is out. Cut back the jer annuals or whatever it isso the mantes that are long lived have room to grow and develop normally. CAVANAUGH: What do you do with your cuttings? STERMAN: It depends on the plant F. It's a plant that's doing well and thriving, I might pot it up and hold onto it until I see another spot that it might fit into. Other plants just not worth saving. And they go to the compost. Or I might give some away. CAVANAUGH: After you have your garden clean out, are there other things to check like irrigation or water flow? STERMAN: Always, always, always. When everything's cut back, you can see what's happening much better. You don't have to lift up branchs. It's revealeded. So it's a really good time to turn on the irrigation one zone at a time, and check and see, do I have any leaks? Places where the spray is misAaligned? Flushing your lines. Because we have terrible water. And even if you have filters, somehow you get little rocks and pieces. So you take the ends off or the caps off, and you turn the line on for a few minute, let it run, and flush the line, this is a great time to do that conversion from inefficient overhead spray, the old stuff, to much more efficient and very reliable drip line irrigation. Because there's room CAVANAUGH: Judy is calling us from university city. Good afternoon, Judy. Welcome to the show. &%F0 NEW SPEAKER: I am dying to know when is the right time to trim birds of paradise down to the ground? STERMAN: You mean the whole thing? NEW SPEAKER: Yeah, so you can really get rid of that dead wood. I've seep it done, then it comes up all fresh. STERMAN: I would be very hesitant to take an entire bird of paradise all the way down. In commercial situations, they do that. But in the home garden, I'd be really hesitant to do that. That said, this would probably be a really good time to get in there and clean out your bird of paradise. You could dig it up, divide it, and replant it. I'd do that way before I would cut the whole thing down. It's not going to be simple because they have very significant fleshy roots. But I would dig it up be divide it into multiple pieces, take out the dead stuff, and put a couple of healthy riso manies back into the ground. CAVANAUGH: Thank you for the call. Would you be afraid to do that because it wouldn't come back? STERMAN: No, but I think you would end up with all this dead stubble at the base, and that would not look very good when the new growth came back. I'm glad you asked that. I think it would look really bad. If you dig it up, take it apart and divide it into smaller plants, you're starting over again with an intact plant. And none of that ground level stubble. CAVANAUGH: What about the cold temperatures that we're having at night now? Is that a problem for particular plants? STERMAN: Well, yes and no. Every plant has what's considered to be its cold hardiness. Depending on where a plant's from, that's a minimum temperature. Below that minimum, it may die back or die completely. It varies from plant to plant, and you have to experiment a little. There's not much that will -- for most of San Diego, most plants we grow, the vast majority are cold-heardy. I get a freeze right now, and this morning when I got up, it was pretty darn cold outside. But there wasn't any ice. And I did notice some of the plants looked a little shrivelled at the top. CAVANAUGH: We've been having really high winds lately. Is there anything you can do to protect your plants or do you need to? STERMAN: You don't really need to protect the plants unless, for example, you have a newly planted tree that isn't well rooted and might blow over. Then you've got to make sure it's staked correctly. And when they put a stake in, you don't want to put the stake against the trunk. You want it about a foot away. 2 or 3 stakes a foot away from the trunk then and there you want to tie the trunk of the plant loosely to those stakes so they have some movement. You don't want to just have it rigid. It'll grow weak if you do that. CAVANAUGH: Laura is calling from Point Loma. Welcome to the show. NEW SPEAKER: I'm in a very hot pocket. The front of my house gets intense sun all day until probably 2:00. I have a passion fruit. It's a fruiting, it's not just ornamental. And I've had it for about nine years. And it's absolutely huge. It's about 20-foot long of trellis. It seems like it's always either flouring or fruiting. And you I've never been able to find a time that looks like the dormant time to prune it back. So I don't know whether to interrupt it when it's flowering or fruiting and when I'm supposed to cut that back for the health and also to control it. STERMAN: This is a great question. In my experience, passion vines, you can cut them basically any time. They grow so vigorously, they will recover so quickly that I wouldn't worry too much about it. I wouldn't cut it back, like, to the ground. But you can probably cut off a third of it, maybe even a half of it easily, and it'll come right back. You used the word control. That's a little hard to do. You can kind of direct it and you can pull it out of places you don't want it, but passion vines are very aggressive vines. Anybody who's considering planting a passion vine, make sure you have enough space, and the tolerance for something that's just gonna grow and grow and grow. CAVANAUGH: Thank you for the call, Laura. I'm looking at the time, and I'm seeing it's going really quickly, and I want to ask you a couple questions about seasonal plants. Plants like poinsettia, that people have this time of year. Can they be kept going throughout the year? STERMAN: Yes, and no. The really hybrid poinsettias, the ones that are fancy, you can plant any poinsettia in your garden. Whether they will grow long-term is a different issue. Those ones you're talking about are bred to be beautiful now. They're not bred to be long-lived. The ones that are more simple, closer to what a poinsettia actually is, if you live on the coast, you can put it in your garden and it will grow quite large. If you're looking for a garden poinsettia, those aren't the best. CAVANAUGH: Lots of people buy live Christmas trees. Can you transplant them? STERMAN: Yes, you can. I would encourage you, though, to find out what kind of tree it is and to make sure that you have much space. One of the famous boo-boos, is if you have an Italian stone pine, come is a beautiful tree, which grows to be 60†feet. CAVANAUGH: Oh, my! STERMAN: When bought my house, the previous owners have planted all these Christmas trees in the backyard, and oh, boy, I made short order of getting rid of because I knew they would get huge CAVANAUGH: My final question. STERMAN: So fast! CAVANAUGH: Is about the class you have coming up. STERMAN: Yes. I'm going to be doing a workshop about how to start your summer and spring vegetable garden from seed, several times throughout county in different locations. It's about two hours, and I bring in everything, the soil, the seeds, the containers, we go through the whole process, and in the end, everyone goes home with their entire garden planted and ready to go. Send me an e-mail to, and in the subject line put seed starting workshop. And as locations become available, I'll let them know and I've got about half a location set up. I'm looking for more locations, especially south and central San Diego. CAVANAUGH: I've been speaking with garden designer and writer, Nan Sterman. Thank you Nan. STERMAN: Thank you.

This is the season that separates San Diego gardens from most gardens around the country. Instead of being covered in snow and ice, our gardens are active and gardeners still have lots of questions about planting and harvesting the bounty of the late fall.

Gardening expert Nan Sterman joined us to share winter gardening tips. Read the comments below for even more info on how to grow a successful garden in the colder months.