Beans are one of the easiest crops to grow well in Missoula, as long as you respect one rule: they hate cold. Unlike lettuce or peas, beans will not tolerate frost and they sulk in cold soil. Plant them at the right time and pick the right type, though, and they will keep you in beans for weeks.
The main decision is what kind of bean you are growing and whether our short season gives it enough time. That sounds simple, but it is where bean plantings often go wrong, usually by planting too early or choosing a variety that runs out of summer before it finishes.
Wait for Warm Soil Before You Plant
Beans are a warm-season crop. MSU Extension gives a soil temperature range of 60 to 85 degrees for snap bean germination, and seeds planted in cold ground often rot before they sprout. Missoula’s median last spring frost is mid May (about May 16 at the airport, per NOAA’s 1991 to 2020 normals), but in about 1 year in 10 it comes after June 1. Waiting until frost danger has passed, then giving the soil another week or so to warm up, is a conservative local strategy that suits our cool springs. In most years that means late May or early June.
MSU Extension’s planting schedule opens the snap bean window as early as a week before the average last frost, and its vegetable gardening guide puts warm-season crops in at about the last frost date. Those are the earliest dates, though, and it pays to hold off if the spring has been cold and wet. There is little advantage to rushing beans into the ground. A planting made in early June will often catch up to and pass one made in mid May that struggled in cold soil. If you want an earlier start, you can warm the bed with a row cover for a week or two before planting.
Bush Beans Are the Safe Bet Here
For most Missoula gardens, bush beans are the way to go. They grow into compact plants about knee high and do not need a trellis. MSU Extension lists snap beans at 52 to 70 days from seeding, and many bush varieties sit near the fast end of that range. That speed matters in a short season. You plant in early June and you are picking by late July, with plenty of summer left.
Provider is an old standby that Johnny’s Selected Seeds says tolerates cooler soil than other beans, and it produces early. Contender is another early, dependable choice. MSU Extension’s planting schedule names both, along with Tendercrop Stringless and Bush Romano, as snap bean varieties suited to containers. If you are new to growing beans, any of these is a good place to start.
One trick that makes a real difference: succession planting. MSU Extension recommends sowing bush beans weekly up to the last planting date, which its schedule puts at about 12 weeks before the first fall frost. With Missoula’s median first frost in late September, that last sowing falls around early July. A single planting gives you a big flush of beans over a couple of weeks and then tapers off. Stagger your plantings until then and you keep fresh beans coming through late summer instead of drowning in them all at once and then having none.
Pole Beans and Dry Beans: Know the Risk
Pole beans climb, produce over a longer stretch, and many people think they taste better. The catch in Missoula is timing. Pole beans mature later than bush types, so they need more of our limited warm season to really hit their stride. They can absolutely work here, but plant them as early as warm soil allows and put them on a sturdy trellis where they get full sun. In a cool summer they may run out of time before they hit full production.
Dry beans, the kind you grow to shell and store, are the biggest gamble. They need the pods to fully mature and dry down on the plant, which can take 90 to 100 days of warm weather. That is cutting it close in Missoula, where the median first fall frost is late September (about September 26) and in about 1 year in 10 frost arrives by mid September. If you want to try them, choose the shortest-season varieties you can find and plant them as early as the soil allows. For most home gardeners here, snap beans you eat fresh are a more reliable use of the space.
Keeping Beans Productive
Beans are not heavy feeders. With the right soil bacteria, called rhizobia, living in nodules on their roots, they can pull some nitrogen from the air. Garden beans are weak fixers, though, and use most of what they fix themselves, so little reaches neighboring plants during the season. They still do not need much added fertilizer. Rich, well drained soil with some compost worked in is plenty. Too much nitrogen actually gives you lush leafy plants with fewer beans.
Water steadily once the plants are flowering and setting pods, since that is when they need it most. A layer of straw mulch helps hold moisture through our dry July and keeps the soil temperature even. Beans have shallow roots, so they feel drought stress quickly.
The most important habit is to pick often. Snap beans that are left on the plant too long get tough and stringy, and worse, they signal the plant to stop making new ones. Pick every couple of days once they start producing and the plants will keep setting beans for weeks. The more you pick, the more you get.
For bean sowing dates alongside the rest of the garden, see the Missoula Planting Calendar.
Sources
- Montana State University Extension, Can I Grow That Here? Vegetable Seed and Transplant Schedules
- Montana State University Extension, Successful Home Vegetable Gardening
- New Mexico State University Extension, Nitrogen Fixation by Legumes (Guide A-129)