Growing Lettuce

Growing Lettuce

Part of Ep. 1302 Lettuce Grow!

Judy Reith-Rozelle of the University of Wisconsin-Madison Experimental Farms explains the importance of soil temperature when planting lettuce.

Premiere date: Jun 29, 2005

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
Inpatient gardeners like to get an early start on the growing season. We know that can be a mistake to plant tomatoes too early. It can also be a mistake if you plant your lettuce too early. We're at the West Madison Agricultural Research Station part of University of Wisconsin-Madison. I'm with the assistant superintendent, Judy Reith-Rozelle. Judy, I always thought, lettuce, you know it says plant as soon as the ground can be worked in early spring, so that's what I did. However, I noticed I have nothing coming up. So, it's not the season, it's something else that I should be paying attention to.

Judy Reith-Rozelle:
You should be paying attention to the soil temperature. That's what's most important with seed germination when you're doing direct seeding in the garden. The soil temperature, a good range is from 40 to 65. And what happens, if you get down in the 30s, you can lose the seed to cold temperatures which we did here. Or, it can take up to 30 days to germinate.

Shelley:
So, you're not getting the head start.

Judy:
You might as well be patient and wait. At 40 degrees, it will take about 15 days. When it gets up to 50 degrees, it only takes seven days to germinate.

Shelley:
We're talking soil temperature, not air temperature. How do I measure my soil?

Judy:
There are three separate ways. You can walk out and be observant, like most gardeners are. Look at the temperatures for the evening and during the day. Make sure that you are monitoring those over a period of time, so you're getting a warmer night and warmer days.

Shelley:
So, that first 80-degree day doesn't count.

Judy:
Right, don't run out and start planting. The other way is you can buy a soil temperature thermometer from garden supply centers, and maybe some garden stores. Go out and measure it. Measure the first four inches of the soil. See what the temperature is. The third one may be easier. If you have access to the Internet, some Web sites will tell you soil temperatures around the state. It's easy, farmers use it all the time.

Shelley:
Why not gardeners? If we're paying attention to soil instead of season, there's also two times a year where we get cooler temperatures. Spring and fall. We could have two crops by paying attention to the soil temperature.

Judy:
In the spring and later in the fall, late August you can start planting again.

Shelley:
Pay attention to temperature, not the season. For Wisconsin gardeners there are hundreds of lettuce choices. We just have a few here. Radicchio, is one of my favorites. Romaines grow well here. And what's this one?

Judy:
This is a butterhead, a very nice little head lettuce with lots of opportunities to use in many ways--

Shelley:
For flavor.

Judy:
And leaf lettuce, which comes in many colors many shapes and sizes.

Shelley:
You just have a few flats of some choices. Do you have some favorites?

Judy:
I have some favorites. Of course, that changes all the time. Right now, one of my favorites is endive. The reason it's one of my favorites-- we've trialed it here at the garden-- It is more heat tolerant, which means that it will bolt more slowly. You can grow it through the summer, and it won't go to seed and get bitter.

Shelley:
So, when we talk about the optimum planting time, there's also a time when it just gets too hot. Most lettuces, we lose the crop or it's bitter. This one is kind of working against that problem. Endive is one to consider. Okay, what else?

Judy:
The other one is a mesclun mix, which is really nice. It has some lettuces, and mustards. There's a mizuna in here, which is an Asian vegetable. It's in the mustard family, so it has a little bite. Both of these, the lettuce and mesclun you can cut them, and they'll grow back. That's a really wonderful part of it. If you cut the head of a head lettuce, it's gone. But this you cut, and it'll come back. The mizuna, we have also trialed in the garden. We've cut it all summer long, and it's come back.

Shelley:
That's this bitey one? This is delicious. And very pretty. Great, thanks.

Judy:
You're welcome.

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