Fertilizing Basics

Fertilizing Basics

Part of Ep. 501 Planning Ahead

Learn what the terms top dress, side dress and broadcast mean in reference to fertilizing your garden.  UW-Extension's Soil Scientist Sherry Combs explains how you should add nutrients to your garden.

Premiere date: Feb 28, 1997

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
Very soon now, were going to be planting our flowers and vegetables in the garden. And then we're going to have to start thinking about feeding those plants. Fertilizing instructions can be confusing, so I'm with UW-Extension's soil scientist, Sherry Combs to try to clarify the matter.

Sherry, I get these instructions, some say "top dress," "side dress." My soil test results said, "broadcast." What does it all mean.

Sherry:
Let's clarify those in a minute. We want to first spend a little bit of time-- hopefully, you've gotten a soil test of your garden area, so you've got your results to work from. The next step that you have to think about when fertilizing is the grade of fertilizer that you're going to purchase.

Shelley:
So, buy the proper stuff.

Sherry:
Yeah, you've got to buy the right stuff. You can go to your local lawn and garden center and look at the grade on the front of the box or bag. Those numbers there, 5-10-5, refers to nitrogen, phosphorous and potassium, always in that order. So, you can match up what your soil test report recommends for grade with what you can purchase in the store. That's the first step. Next is to understand how much you need to apply.

Shelley:
Well, that's confusing, too. My soil test results said to use a pound fertilizer for 100 square feet. I don't have a scale, so I just took the bag out into the garden.

Sherry:
Most people do, unfortunately, and they way over apply. An easy way to avoid needing a scale is to just measure about two and a quarter to two and a half cups of fertilizer. That's about equivalent to a pound.

Shelley:
So, this equals a pound.

Sherry:
Yes.

Shelley:
Now, that's not a lot for 100 square feet.

Sherry:
No, assuming that if that's your garden area, you've got to spread it very carefully in order to get it spread uniformly.

Sherry:
Okay, let's talk about the spreading.

Sherry:
Yeah, let's take you through a garden season, here, with the different types of fertilizer application methods that we have. We recommend different ones for different crops at different times of the growing season. The first, and probably the most important, is the broadcast application. That's really just taking the fertilizer that you've measured, knowing the area that you want to fertilize, and spreading it evenly over the soil surface, either by hand or with a drop spreader.

Shelley:
Now, we're doing this before we've planted anything.

Sherry:
Yes, you don't have anything planted in here, because after you spread it on the surface, you're going to come in with some tillage, maybe a rototiller or digging, whatever you can do.

Shelley:
You say that this is the most important one of the entire growing season?

Sherry:
Yeah, we apply the bulk of the plant needs at this time. And we're also able to incorporate it in the rooting zone of the plant. So, we're not limiting what the plant can use, but incorporating it through the whole root volume.

Shelley:
What about side dressing? What does that refer to?

Sherry:
Side dressing is a specialized technique for later in the growing season. When crops are growing very vigorously, sometimes they run out of nitrogen. So, we use a material that has a high nitrogen value, the first number on the box. And, assuming that this was our high-nitrogen material, we would be applying a band of fertilizer along the side of all the plants.

Shelley:
Can you be too close? At what distance?

Sherry:
If you get too close, you can get some root burns. So, keep it three to six inches away from the plant.

Shelley:
Now, am I actually digging this in?

Sherry:
You might be following it with some light cultivation. It would be light, because of root damage. Some crops that you might be using side dressing on is sweet corn, tomatoes, carrots-- long-season crops.

Shelley:
Okay. Well, this is my hypothetical perennial bed. These are permanent and they're up. There are no rows, so I can't side dress. I obviously can't broadcast and do any digging, I'll kill them.

Sherry:
Well, now you have to rely on a top dress application. Again, use a grade that's recommended on your soil test result. Come in and just over the tops of the plants...

Shelley:
Right on the plants?

Sherry:
Yeah, apply your fertilizer right on the plants. Now, you can see, maybe, in some areas, we've had some fertilizer stick on the leaves. You want to make sure that you either brush the leaves or irrigate so that you can wash the fertilizer granule off the leaf and avoid the burn that you might get.

Shelley:
So, do it before rain or get out there with a hose.

Sherry:
Yes.

Shelley:
That takes me through most of the growing season?

Sherry:
It takes you through the whole growing season.

Shelley:
Okay, great. Thanks, Sherry. But remember, the most important step is the first one: the right fertilizer, properly measured.

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