Cold Frames

Air Date: February 20, 1998

(Loud sound, sliding door opening?)

WEISHAN: Okay, Steve, let's go outside.

(Door slides; footfalls and bird calls)

WEISHAN: Careful on the ice here; it's treacherous footing.

CURWOOD: Okay.

(More footfalls)

CURWOOD: So, Michael, it looks like you've gotten some of the freezing rain that has bedeviled the northeast this winter.

WEISHAN: Ah, yeah.

CURWOOD: Your power lines aren't down, thank heavens. But still, we have a smooth, hard, and slippery crust here in your back yard. Michael Weishan is Living on Earth's gardening expert. And Michael, you've brought us outside of your nice, warm greenhouse to look at your cold frames. Now, how does this work? How does this thing, which is outside here in the cold, manage to get the garden going earlier than it might otherwise go?

WEISHAN: Well, it's actually pretty ingenious. It's essentially a miniature solar greenhouse. And it's not only for aggressive gardening types. It's for anybody who's interested in growing crops either earlier or later in the season than they would normally do so. And especially in the northern, colder parts of the country, this is almost a necessity for getting things going and started.

CURWOOD: Okay, now, let's describe what the cold frame is here.

WEISHAN: Yes, it's essentially a box built of timbers with glass or, in this particular case, plastic windows on top that raise and lower. For the average home owner, even for the rooftop gardener, you can buy a kit for about $100 from most of the gardening supply houses that is ready to go and you just put it on the ground. I've seen people use hay bales as the walls, side walls, and an old window as the top. Anything that will essentially give you a square structure that you can put some type of glass or hard surface on top of.

CURWOOD: And which side should it face? Down to the south, is that the way we're looking?

WEISHAN: This one faces to the south, and that's by far the best location. Because you're trying to capture solar heat.

CURWOOD: Now, what months can you use a cold frame to grow plants?

WEISHAN: Well, it's both ends of the growing season. So here we are, standing out in late winter, and we're about to do some planting. So essentially as soon as you can get out to the cold frame, and it's not covered with snow, you can actually start working. We also use it actually at the end of the summer for growing melons and sweet potatoes, which are too long season for this climate. So as soon as the plants are out, then we plant a whole nother crop that will grow here through the summer and way into the fall, which we generally harvest in November, long after the first frost.

CURWOOD: What are the plants you're going to put in here?

WEISHAN: Well, we're going to plant today I've just chosen some of my favorites red leaf lettuce; a little arugula, because that really spices up an early spring or late winter salad; and some romaine, which is another one of my favorites. But you could easily grow radishes, and that's a great project for the kids because they come up very quickly and you can see the plants and eat the product within about 30 days. Spinach is another cold weather crop. Anything that you have room for, quite frankly, depending on the size of your cold frame.

CURWOOD: Okay.

WEISHAN: Okay, so let's go. I'm just going to -- I'm going to hand you the seeds, Steve, and I'm going to hand you a tool here. And I'm going to open the frame.

(Loud sounds; ice falling)

WEISHAN: All right.

CURWOOD: I'm going to say it's pretty amazing to be knocking the ice off of this cold frame and planting at the same time. (Laughs)

WEISHAN: It is amazing. What's even more amazing is to come out in the middle of a snow storm or late in the season just before Christmas and knock the snow off the glass and raise it up and find a perfectly healthy crop of fresh organic vegetables. What more can you ask? It's really a terrific ancient technology.

CURWOOD: Why wouldn't it work all the way around the calendar?

WEISHAN: There are several considerations. One is that the base temperatures, at least in Boston, it's a little too cold. If you lived in the Southern parts of the country, you could probably do it. The other issue is that light is a great factor in plant growth; and quite frankly, in the middle of winter there's just not enough light to get the plants growing. They'll sit there, almost dormant, for most of the winter, until the spring sunlight arrives.

CURWOOD: Okay, let's go.

WEISHAN: Okay. Let's try a red leaf lettuce here first. You like red leaf lettuce?

CURWOOD: Oh, I do.

WEISHAN: All right. Just pour some into your hand like that.

CURWOOD: Okay.

WEISHAN: And then take your fingers like you're taking a pinch of salt. You get much better control. Go right down the line there.

(Finger rubbing sounds)

WEISHAN: All right, there's our completed row.

CURWOOD: So, what do I do next, here?

WEISHAN: What you're going to do next is water, and this is a crucial element in a cold frame. Because it's outside, everyone, myself included (laughs), seems to forget to water it. Because you think well, it's outside, it's raining, you know, it doesn't need water. But as you can see here, where the snow melt hasn't actually dripped through the frame, the soil is quite dry. So, we're going to actually water this heavily and then let it go. And we'll want to check it periodically to make sure that there is sufficient moisture for the seeds to sprout.

(Splashing water)

CURWOOD: That's an important tool you've got there in the back corner. What... let me

WEISHAN: (Laughs) That's a hops harvest. That's my father's souvenir beer can. He actually built these cold frames for me a number of years ago. That was his much well-deserved reward at the end of a very hard day. It was 90 degrees one summer. But it reminds me of him so I"ve left it there over the years as sort of a tribute.

CURWOOD: (Laughs) Michael, thanks for helping us get the garden started.

WEISHAN: My pleasure. Thanks for coming. Once again, this free labor's always appreciated.

CURWOOD: (Laughs) Michael Weishan is editor of Traditional Gardening. And if you would like to ask him a question about cold frames or anything else about gardening, check out our Web site at www.loe.org. That's www.loe.org.