If you want a vegetable with a very good chance of success in Missoula, grow summer squash. Zucchini and its relatives are some of the most productive, forgiving crops you can put in the ground here. They grow fast, they handle our season easily, and most years the only real problem is keeping up with the harvest. The running joke about leaving zucchini on neighbors’ porches exists for a reason.
Variety choice with summer squash is less about beating frost and more about flavor, plant size, and how much you want to deal with. Almost all of them mature quickly enough for our season, so you can pick based on what you actually like to eat and how much room you have.
Plant After the Soil Warms
Squash is a warm-season crop, so the main rule is to wait for warm soil. MSU Extension lists 65 to 85°F as the soil temperature range for squash germination, and seeds in cold soil rot easily, so there is no benefit to rushing. 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. Squash usually goes in from late May into early June here, after a look at the 10-day forecast.
Once they are up and the weather is warm, summer squash grows fast. Most varieties reach first harvest in roughly 45 to 60 days, though seed companies count those days differently, some from sowing and some from transplanting. That still leaves plenty of room before the median first fall frost in late September (about September 26). You can direct seed them or set out transplants for a slightly earlier start. MSU Extension suggests about 4 weeks to grow a squash transplant.
Best Zucchini Varieties
Zucchini is the most popular summer squash for good reason. It is productive and versatile.
Black Beauty is the classic dark green zucchini, a widely grown open-pollinated standard that is easy to find and a common first choice. Dunja is an early hybrid zucchini on an open plant, listed by Johnny’s at about 47 days. Costata Romanesco is an Italian heirloom with ribbed, pale-striped fruit that catalogs praise for its nutty flavor and texture, though the plants are larger and less productive (Johnny’s puts yields at about half those of hybrid zucchini). If flavor is your priority and you have the space, it is worth a try.
For smaller gardens, look for bush-type zucchini bred to stay compact. They give you a good harvest in less space, which matters in a raised bed.
Where to find the seed: Botanical Interests is the seed company we use ourselves, and it carries both Black Beauty and Costata Romanesco. These are affiliate links, so if you buy through them, Garden City Plant Care may earn a commission at no extra cost to you.
Yellow Squash and Patty Pans
Summer squash is more than zucchini. Yellow crookneck and straightneck varieties are often described as slightly sweeter and more delicate in flavor, and they add color to the harvest basket. They grow just as easily as zucchini here.
Patty pan squash, the little scalloped, flying-saucer shaped ones, are worth growing for both looks and taste. Varieties like Sunburst, a bright yellow patty pan, are productive and pick beautifully when small. They hold up well on the grill and roast nicely, and they are a fun one if you have kids in the garden.
The Secret Is Picking Often
Beyond variety, harvesting makes a big difference with summer squash. Squash is most tender when you pick the fruit small, zucchini around six to eight inches, patty pans when they are a couple of inches across. Left on the plant, they balloon into watery, seedy baseball bats, and plants left carrying big, maturing fruit tend to set fewer new ones.
In peak summer, check your plants every day or two. They produce that fast. Picking regularly keeps the plant cranking out tender new squash for weeks, which is exactly the problem you want to have.
Give squash full sun, rich soil with compost worked in, and steady water, and it will reward you generously. The big leaves wilt dramatically in afternoon heat and usually perk back up by evening, so do not panic and overwater. Water deeply at the base in the morning instead.
For the long-season types, see How to Grow Winter Squash in Montana, and for planting dates across the rest of the garden, the Missoula Vegetable Growing Guide.
Sources
- Montana State University Extension, Can I Grow That Here? Vegetable Seed and Transplant Schedules
- NOAA NCEI, U.S. Climate Normals 1991 to 2020 (Missoula International Airport)