from the employee owners at Gardener's Supply Co.

How to Double Your Pea Harvest

sugar snap peas

You can increase your pea harvest dramatically by using an inoculant

There are a couple tricky things about growing garden peas. The first is planting time. Plant too early and your peas may be stunted by cold soil and frost. Plant too late and your plants may start to shrivel up from the heat just as you get ready to start picking peas.

Every year is a bit different, but generally I try to get my peas in a full month before the last frost date. (Be sure to soak the seeds in water the night before you plant them.)

Providing adequate moisture is another essential for a good crop of peas. Peas have shallow roots and are very thirsty plants. The soil around your peas should stay consistently moist, and depending on rainfall, that may require watering deeply two or three times a week.

Proper trellising is also key. But the easiest and most dramatic way to increase your yield is to apply an inoculant at planting time.

Peas are in the legume family, which means they have the unique ability to absorb nitrogen from the air as well as from the soil. But in order to achieve this special trick, their roots must be in the presence of a particular strain of rhizobial bacteria: Rhizobium leguminosarum biovar vicaea.

Wherever this bacteria enters the roots of the plant, it forms a hard little nodule. Inside the nodules is where the atmospheric nitrogen is converted so it can be utilized by the plant as a nutrient.

Healthy soils already contain many types of this beneficial rhizobial bacteria, but the concentration isn’t high enough to maximize performance.

A $5 envelope of inoculant contains about 1½ oz of powdered bacteria—a little more than 2 tablespoons. Though the package says it will treat 5 lbs of seed, I now use 2 packages on ½ lb of seed (planting a double row, 20 feet long) and see a significant difference in vigor and yield.

The directions on the package usually say to put your pea seeds right in the plastic envelope and shake them around until they’re coated with inoculant. I haven’t found this to be very effective. Instead, I open a furrow down the entire length of the row, put in the seeds, shake a little inoculant over the top of the seeds and then cover them up.

Not all garden centers stock inoculant, so to be safe, I order mine by mail. It’s important to purchase a fresh supply each year. Make sure that you purchase the strain of Rhizobium that’s right for peas—both Johnny’s Selected Seeds and Vesey’s Seeds have it. Sometimes all that’s available is a blend that’s suitable for both peas and beans. That works fine, but remember roughly half of what you’re applying won’t be of any use to the peas.

Have you had good success using inoculants for your peas or beans? Leave a comment!

-Kathy LaLiberte, Director of Gardening

4 Comments

  1. Anonymous
    March 30, 2008    

    Is it too late to add an inoculant if my snap peas have begun to sprout? Will it work to mix some inoculant with sand or vermiculite and scratch it into the rows near the sprouts? Thank you.

  2. April 1, 2008    

    I’d say better late than never, especially if this the first time you have planted peas in your garden. It’s best to put the inoculant on the seed at planting time, but it’s worth a go even at the sprouting stage. Scratch it in as close to the roots as you can because that’s where the inoculant will do the most good. If mixing it with a bit of fine sand or vermiculite helps to spread it more evenly, go ahead. The fine inoculant powder may fall to the bottom of the mix, though, so keep it stirred up. -Ann Whitman, Staff Horticulturist

  3. Anonymous
    April 2, 2008    

    I use stakes but not the wooden ones. They may not be the best in terms of being ecofriendly, but they last forever and don’t break or bend. They are much cheaper than other systems. I have more cloth lines than I need so I tie the stakes to them and picking tomatoes is a breeze.

  4. Alex McAllister
    May 23, 2014    

    I always use inoculant and soak almost all day in a small amount of water with the powder mixed in. So many “garden” places don’t know about it.

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