Forage Radish Cover Crops Guide What You Need to Know

Forage Radish A Green Manure Cover Crop

forage radish cover crop in the ground

Gardeners and farmers can benefit by using forage radishes, also called daikon, tillage, or Japanese radishes, as a cover crop for their soil. They provide benefits that other cover crops like cereal rye and clover can not offer.

The name Tillage radish makes a lot of sense since it is a plant that effectively performs a similar act of tilling the soil.

Forage radish grows very fast in fall and scavenges nitrogen and other nutrients. The high growth rate allows them to protect the top of our soil by stopping weeds from moving into our garden.

When the radishes rot the following season, the nutrients collected from deeper in the ground become available to our other plants.

When we use forage radishes as a cover crop, we will keep them in the ground all winter.

When winter comes, it will kill the radishes. In the spring, they will break down, adding nutrients to the soil. There will be a foul smell while the radishes decay in the spring. Many think it resembles rotten eggs or a natural gas leak, but the scent will not last long.

A downside is the price of radishes compared to more traditional cover crops, but it should not make that big of a difference for a home garden.

Also, if you live somewhere where deer have access to the plot and are not trying to feed them, you will want to use a different crop type.

What Are The Forage Radish Growth Stages?

First, we will plant the seeds in our soil. The seed will take in water, swelling bigger until the seed cracks open. The root will grow down, and the shoot begins growing up. Over five to ten days, the shoot will emerge above ground, moving the plant into the second stage.

Seedling. Once the shoot has emerged, we have moved into the seedling stage. When the leaves emerge from the soil, the plant begins the process of photosynthesis. The radish is most sensitive to any changes in moisture and temperature at this point.

Maturity. Radishes are at their full size (1 to 1 1/2 inches in diameter) and take 8 to 10 weeks to reach full maturity on average.

Past Maturity. At this point, the radish will begin to produce flowers. This will make them no longer edible, but it is not a problem when we use them as a cover crop since we do not remove them from our garden.

When to Plant Forage Radish

We want to plant them by the end of the season, but before the frost is coming.

Since we are using them as a cover crop and not to eat, we want to get them planted in the ground at least 4 weeks before the first frost.

If you are using them to naturally till the soil, getting them in the ground closer to the 10-week mark is better.

Forage Radish Fertilizer Requirements

Radishes are known for their fast growth and low nutrient requirements.

If you are not using the forage radish as a cover crop but plan to eat them, you may want to use fertilizer to maximize its growth.

Organic fertilizer like bone meal works well for growing the largest radishes possible. It contains high levels of phosphorus and calcium, helping root growth.

Any fertilizer with an N.P.K. of around 5-10-10 works really well. The higher the nitrogen, the more leaf growth will appear above ground.

High levels of nitrogen can also stunt the root's development.

How to Plant Forage Radish Cover Crop

If you want to add some fertilizer, you should add it before planting but ensure it is not high in nitrogen an N.P.K. around 5-10-10 works best.

We also need our soil to have a pH level between 5.5 to 7.5 pH. Outside of this range may prevent them from being able to grow.

I plant my forage radish about half an inch to one inch deep. The easiest method for me is using a garden rake to remove soil from the area where I am planting the radishes.

Now just toss my seeds around the freshly raked area.

I will use my hose and add water to the seeds I just laid down to help them stay in place a little better.

Now I take the rake and add the soil I removed back over the top of the seeds. I will then give the ground another quick watering.

I am not worried about overcrowding since I use them to protect the soil. In the next 10 days, if you notice any bare area with no sprouts, just use a stick or something similar to make half-inch holes and add some more seeds to ensure your soil is well covered.

Forage Radishes Germination Time

Multiple factors will alter how long it takes for our forage radishes to germinate. The depth it is planted, the available moisture, and the temperature can all change the speed the plants germinate at.

Temperatures for successful germination need to be between 45-77 °F (8-24 °C). Ideally, we want the temperature range to hover between 65°F(53.5°C) to 77°F (25°C).

When our soil has adequate moisture and a temperature of 65°F (18°C), we can see the seeds germinate as quickly as 3 to 5 days.

It can take up to 2 weeks in colder weather before we see the radish sprouts.

Do Radishes Deplete The Soil?

If you are growing them for use outside your garden, they will remove some nutrients from your soil.

But when using them as a cover crop, we generally leave them in our garden over the winter months to help protect our soil.

Once the frost comes, our radishes will die and rot when the spring comes. Leaving them in the ground will allow them to act as a green manure source returning the nutrients to our soil.

What Does Radish Do To Soil?

Forage radishes have nice and thick roots, and the roots will drill through our soil and help to reduce how compact it is.

Since they will reduce how compact our soil is, it will help to increase our garden's aeration and water infiltration.

Leaving the radishes in the ground to rot will also help to naturally build up our garden's soil.

The added aeration will make it easier for our following crops' roots to penetrate the soil, allowing them to grow a more extensive root system.

Another benefit for our soil is the radishes ability to clean up our soil by scavenging nutrients while suppressing weeds.

They will also add what is known as biofumigants which are natural chemicals that can help to deter pests from our garden. Research has shown that the residue is specifically good at reducing root-knot nematodes in the soil.

Killing Forage Radish Cover Crop

Unlike many other cover crops, we do not have to actively do anything to kill this cover crop.

When winter comes, it will kill the radishes for us. You can till them into the soil if you really want to in the spring, but many just leave them to rot in the ground as is.

Leaving them in the ground allows them to act as green manure returning the nutrients they scavenged and building up the organic matter in our soil.


Forage radishes have been growing in popularity as a cover crop over the past decade.

You can add them with other cover crops like cereal rye or wheat to help add even more organic material into our soil.

They will scavenge nutrients while providing a deterrent against pests and weeds moving into our garden.

The only downfall is the smell that they produce when rotting in the spring.

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