What if you could cultivate vegetables that were tasty, nutritious, easy to grow -- and produced their own fertilizer? If you think this sounds too good to be true, think again! We're talking about legumes -- peas and beans to most of us gardeners. Besides these familiar garden crops, the legume family includes lentils, soybeans, and peanuts, as well as field crops like alfalfa and clover. What they all have in common are nutritious edible seeds and the ability of their roots to "fix" nitrogen from the air, changing it into a form they can use with help of certain soil bacteria.
A Nod to Nodules
The process of nitrogen fixation starts when soil-dwelling bacteria called Rhizobia invade the roots of legumes, forming nodules on the roots. Inside these swellings, the bacteria change the nitrogen from its form in air, which is unavailable to plants, into a form they can absorb. In return the Rhizobia get nutrients and a protected spot to live. This beneficial partnership is called a symbiotic relationship. It also benefits you as a gardener because you don't need to worry about adding extra nitrogen to the soil in the form of fertilizer for your peas and beans when the bacteria are hard at work.
Most of the fixed nitrogen goes directly into the plant that is harvested (as opposed to a legume cover crop that is turned completely into the soil) and will help increase nitrogen in the soil only to the extent that roots or other plant parts are left to decompose and recycle their nutrients.
If you are planting peas and beans for the first time in your garden, it's a good idea to add a legume inoculant at planting time. This is a powder that contains the beneficial bacteria. You simply dust the seeds before planting or sprinkle the powder into the planting furrow to make sure you have a thriving population of microbes. But once the Rhizobia have been introduced, they become established and don't need to be added yearly. Be sure to purchase inoculant powder with the correct strain of bacteria for garden peas and beans.
Here are some the many varieties of peas and beans we are offering this season.
'Contender' Bush Bean (49 days)Very early and highly productive, this bush bean bears 6-7 inch long, stringless, tender pods.
'Kentucky Wonder ' Garden Pole Bean (65 days) One of the best home garden pole varieties, this prolific climber is great for fresh eating, canning, or freezing.
'Christmas' Pole Lima Bean (88 days) A long season variety, the large, flat beans can be picked at either the green shell or dry stage.
'Alaska WR' Smooth-Seeded Garden Pea (56 days) A good canning variety with light green, straight, blunt pods and small, light green peas low in sugar.
'Little Marvel' Wrinkle-Seeded Garden Pea (62 days) Heavy yielding vines are only about 15 inches tall and produce dark green, round, tender, sweet peas.
'Black Crowder' Southern Pea (63 days) Unlike their garden pea cousins, southern peas are warm-weather lovers that won't tolerate frost. These peas have a deep purple cast when shelled green, turning black when dry.
Pea Planting Pointers
Peas like it cool, so you can start planting as soon as your soil is dry enough to work. But if the soil is too cool (below about 40 degrees) and wet, seeds can rot before they germinate. One solution is to plant seeds that have been treated with a protective fungicide. Another is to pre-germinate your peas to get them off to a reliable start. Wrap the seeds in a moist paper towel and put them in a dark, warm place for a few days. Check daily and as soon as you see the tiny root begin to emerge, carefully pop the seeds into their outdoor planting bed.
Provide your peas with a support around which their tendrils can curl. Tall varieties work well on a trellis, but even shorter varieties will benefit from some support such as pea brush, short lengths of twiggy branches pushed into the soil. Be sure to put any supports in place before planting seeds.
Once the harvest starts, pick pods frequently. Garden or English peas (the ones you shell) are ready when the peas have filled the pods, but the pods are still a bright rather than dull green. Harvest edible-podded snow peas when you see just the beginning of the peas inside the pod, but the pod is still flat. Snap peas also have edible pods. Pick them just as the pods start to fatten, but before the seeds really begin to swell. If you overlook any pea pods and they become too mature for good eating, pick them and add them to the compost pile so that the vines keep producing well.
Peas also make a good fall crop in many areas. To determine when to plant, add about two weeks to the days to maturity for the variety you're planting, then count back this number of days from your fall frost date.
The Buzz on Beans
Unlike peas, beans are warmth lovers. So don't rush your bean planting. Wait until your soil is warm and dry, the weather is settled, and the danger of frost is past before tucking seeds into the soil. Pole beans are the most demanding of warm soil conditions, so put these in about a week after you make your first bush bean planting. Especially if you garden in heavy soil, planting in raised beds will let you get your bean crop off to the earliest start.
To minimize disease problems in the bean patch, practice a three-year rotation for their planting location, if possible, and avoid working with plants when the foliage is wet. Use drip irrigation or soaker hoses to provide water, or irrigate early in the day so the leaves dry quickly.
Bush beans mature quickly and set their crop within a short period of time -- a boon if you are growing to freeze or can them. Make successive, small sowings every few weeks for a continued harvest. Pole beans don't bear as much all at once, but the harvest goes on all season long, making these a great choice for many home gardeners. Their tall vines climb by twining and need a strong support 6-8 feet tall to clamber up.
Pick beans when the pods are firm and crisp, but before you can see the seeds swelling within them. The more you pick, the more pods the plants will produce. Plants are somewhat brittle, so pick carefully -- hold the vine in one hand and pull off the pod with the other to avoid breaking the stems.
Question of the Month: Growing Shell Beans
Q: What are shell beans and how are they grown?
A: Shell beans are grown for their seeds rather than their pods. As with garden peas, the bean pods are shelled to harvest the beans inside. Pick when the beans inside the pods are their full size, but the pods are still firm and not dried out. Cook shell beans by simmering gently until tender, from 10-60 minutes, depending on the variety and maturity of the beans. Dried beans are similar, but the pods and seeds are left on the plant until they are completely dry. Some beans, like limas, may be harvested at the shell stage for fresh eating or left on the vine to ripen for a dried bean harvest. 'Taylor Dwarf Horticultural' bean is an heirloom shell bean variety with pinkish-tan beans marked with red. Shell and dried beans are grown just as you would snap beans, but take longer before they are ready to harvest -- usually about 60-70 days for shell beans; 85-100 days for dried beans.