Of the three common garden vegetables that are grown for their edible seeds—peas, beans, and corn—peas are my favorite. They can be planted right off in the spring and thus provide a no-wait thrill for gardeners itching to plant. They also improve the soil wherever they grow, and they taste good—really good.
Until the 1980s there were two basic types of peas for fresh use: the traditional shelling pea, and the flat, edible-podded kind called, variously, snow peas, Chinese peas, or by the French, “pois mangetout,” or “eat-all” peas. Now we have a third kind, a best-of-both, edible-podded shelling pea, called the snap pea. The first snap pea, called Sugar Snap, was released in 1979 and was awarded an All American Selections Gold Medal; that is just about the highest award a vegetable can receive.
Peas go in the last part of our rotation, so that the nitrogen-hungry leaf crops which follow can benefit from the fertility that they help build in the soil. Like beans, peas are legumes, and their roots, under the proper conditions, will support a population of bacteria called rhizobia, which are capable of extracting nitrogen directly from the air—and converting it to the plant-usable form of nitrates. In the process some of this nitrogen as well as significant amounts of phosphorus are made available to the host plant. That is good for the peas; and after harvest, when the plant residues are turned under or composted, the remaining nitrogen these bacteria have “fixed” becomes available to other plants as well.
The bacteria that perform this unpaid service are present in most soils, (at least in those that have grown peas and beans before), but it makes good garden sense to be sure, and so most experienced gardeners “inoculate” their pea seed before planting. The process is simple. A dried, commercially propagated culture of the proper strain of rhizobia is dusted on the seed just before planting, and then, once in the soil, it multiples just as the peas are sending out their first tentative roots. That guarantees an abundant supply of bacteria early on in the pea’s growth.
Plant your first peas as soon as the ground can be worked in spring. If the ground is reasonably fertile, no fertilizer is necessary; but we spread a couple of pounds of a 50/50 mix of wood ash and colloidal phosphate to provide a ready source of potassium and phosphorus, and to buffer the natural acidity of our boggy upland soil. A soil test will tell if this or some other minor treatment might be a help in your own particular situation.
We then sow inoculated seed of all the climbing peas one inch deep, in two rows two inches apart down the center of a three-foot-wide bed. After the seed is in place we put up a trellis for the vines to climb. All peas—except for the so-called leafless bush types—do better if given something to climb on. Not only does trellising make harvesting easier, allowing more air to circulate among the vines—a great help in preventing disease—but it also helps them grow more quickly and vigorously, by exposing the pods to sunlight. A pea pod is actually a modified kind of leaf, and a significant amount of photosynthesis takes place right in the pod if it is exposed to sunlight, instead of being lost in a tangle of vines snaking along the ground.
Tall types will need a sturdy trellis at least six feet tall. We use the same trellis design as for pole beans, but with more horizontal lines, as peas climb by clinging, not twining. Shorter cultivars can get by with posts that are four feet tall. Untreated twine shouldn’t touch the ground, or it will rot before the crop is harvested, but it is essential that the first horizontal line be only an inch or so above the soil surface. That way the plants can find the trellis early on.
They do actually “find it”: as pea tendrils grow, they rotate slowly in a widening arc through the air until bumping into an obstruction, and then try to wrap their tendrils around it. Something thin like a string, wire, or small, brushy branches is just right. But peas will not climb a pole or a picket-type fence, as the tendrils are not long enough to wrap around and grab hold of anything larger than about an inch in diameter. At the end of the season, just cut the twine from the trellis, and compost the whole mass of plants and twine.
Bush, or leafless, peas are even easier to manage, because they don’t need a trellis at all if you plant them in such a way that they can support themselves. This can be done by sowing three (or more) rows ten to twelve inches apart, or by broadcasting the seed evenly across the surface of the bed and then tilling or raking it in to the proper depth of one inch. The final density of broadcast peas should be one plant every four square inches or so. Either way, as the plants grow, their abundant tendrils (which, like the pods, are just modified leaves) intertwine, and the plants, with their stiff, dwarf stems, hold each other erect. Overall, we have found that three rows per three-foot bed produces better peas than simply broadcasting the seed, at least for a spring crop.
There are two traditional ways to lengthen the pea harvest: either plant a range of cultivars in varietal succession, or plant the same cultivar more than once, say every two weeks, so the plantings mature over a longer period come summer, known as temporal succession. Personally, I prefer the first method, partly because it saves having to remember to replant, and partly because it gets all the peas in early.
I like to interplant peas with spinach, because spinach does best if planted right away in the spring (or in late summer). We plant a row of early spinach six inches or so in from each edge of the bed (a foot out from the trellis on either side) at the same time we sow the peas; by the time the peas have flowered six weeks later, the spinach is ready to harvest.
Our final plantings of peas every season comes in midsummer, during the first cool spell after the days start to shorten. Then we inoculate and plant bush pea seed for a fall harvest sixty to eighty days later, shortly before or after the first fall frosts. To time a planting like this in your own garden, simply count back eighty days from the first frost, and seed during the first available cool spell. Pea vines are hardy down to the teens (around 18F-7C) until they flower, but the blossoms (and later the pods) are not. Even a light frost during flowering is enough to cause a failure of pod set.
That’s not a problem with bush peas, though, because the absence of a fence jutting up in the middle of the row makes them a snap to cover. We use a piece of floating row cover left over from our spring plantings of broccoli, and we have found that it will protect our peas down to at least 25F/-4C. If frost is predicted (or even seems likely) we lay the floating row cover over the pea row and pin it down with #9 wire pins.
Powdery mildew, mosaic, wilt, and enation virus (spread by aphids) are the primary pea diseases; there is not a whole lot to be done about them. Crops planted early and grown on trellises, (or, in wet soil, on raised beds) will be trouble-free most seasons. We’ve found that even during a cloudy, wet, still season, when disease pressure is highest, we will still get a decent crop before the vines give out. A worse problem is not planting on time; if the weather turns unusually hot before the vines have gotten up to size they may never make it. Good garden sanitation and proper rotation are a big help, too.
Snow peas can be harvested anytime after the pod begins to emerge from the flower. Most gardeners harvest snow peas just as the seeds begin to swell, which is known as the “slab pod” stage. Depending on the use we have in mind, we harvest at whatever size is appropriate: snow peas are actually sweeter once the peas have swollen and the pods have begun to curl around, but the texture of the pod becomes tough and stringy. Regardless of your needs, be sure to keep all peas thoroughly picked off, because if the vines are allowed to mature any pods at all they will stop producing new ones!
Shelling peas, whether bush or climbing, should be harvested after the pods have completely filled out, but before they have lost the sheen of youth. That may sound a bit vague, but the pods really do have a luster that they lose once the peas have matured and are beginning to ripen as seed. Just as with sweet corn, once this happens all the sugars that have concentrated in the seeds-to-be start converting to starch, and the peas, instead of being sweet and tender, get increasingly bland and pasty. There is one other way to recognize when this moment has arrived: check the seam of the pod. When immature it looks like the seam on a pillow turned inside out; at harvest time it will look like the same seam, turned right side out and fluffed up. Start checking about three weeks after the plants begin to flower.
Snap peas can be treated either way: harvested anytime after they emerge from the flower until they fill out completely, and then eaten whole—pod and all—or shucked out and eaten alone. They make a fantastic garden snack food to munch while you are leaning on your hoe contemplating the fate of the universe.
Bush peas represent the conscious combination of three genetic traits: dwarf stems, production of tendril-leaves (since tendrils are actually leaves), and relatively stiff, erect stems. Their benefits have already been discussed, but I want to touch on them again because pea breeders have found that these genetic traits do not seem linked with any negative characteristics, and so it is likely that this low-labor habit will be bred into more and more of the cultivars currently available. Sometimes called “leafless” peas, these kinds actually do have leaves—one at the base of each tendril branch, called a stipule leaf, instead of the normal two or three per branch.
The key element to growing these bush peas is to realize that they were originally bred for the freezer trade, and so they have been selected to mature all at once. That is good for the home gardener who freezes peas, too, but it also means that you need to pay close attention to the plot once they near maturity, because when they are ready to be picked there can be no delay. Ninety percent of the problems I have heard of with bush peas are related to improper, delayed harvesting.