Herbs are one of the most satisfying things to grow in Missoula because most of them require very little from you once they are established. A few pots on a sunny step or a small dedicated bed can keep a kitchen supplied all summer.
That said, growing herbs in Missoula is not one-size-fits-all. Some are perennials that usually come back every year with little help. Some want the coolest part of the season and disappear in July heat. And a couple, basil especially, need you to treat them almost as carefully as tomatoes. Knowing which is which saves a lot of frustration.
Herbs That Come Back Every Year
These are the herbs worth planting once. Most of them handle Missoula’s winters (USDA zone 5b) with little help and show up again in spring, though drainage and exposure make a big difference for some.
Chives are hardy to zone 3, according to MSU Extension, so Missoula winters do not faze them. They come up early in spring, produce all season, and multiply on their own. Plant them once and they will be there for years. The purple flowers are edible too, and they look nice in the garden.
Mint is almost too easy to grow in Missoula. It survives hard winters, spreads aggressively, and produces more than most households can use. The important thing to know: plant it in a container rather than directly in the ground. In the ground, it spreads into everything around it within a few seasons and becomes difficult to remove.
Oregano is a hardy perennial here, though MSU Extension suggests some winter protection, especially on a hot south or west exposure. Thyme is more borderline. MSU calls it only marginally hardy in parts of Montana, so in Missoula it comes back best with sharp drainage and some shelter, and old woody plants are worth replacing every three or four years. Both do best in well-drained soil and a sunny spot. They are drought-tolerant once established and need very little attention.
Sage usually comes back in Missoula as well, though MSU Extension calls it marginally hardy in parts of the state. It gets woody over time, so cutting it back in spring keeps the plant productive. Good drainage matters for sage, especially through wet springs. If you are not sure how your soil drains, the guide on Missoula soil types covers how soils vary across the valley.
Lavender can be perennial in Missoula with the right variety and good drainage. Hidcote and Munstead are among the more cold-hardy English lavenders. They do not love wet feet, so raised beds or slopes with excellent drainage give you the best chance of overwintering successfully. Heavy, poorly drained soil, found in some Missoula yards, is the main thing to watch for.
Rosemary: Treat It Like an Annual
Rosemary is perennial in warmer climates, but Missoula winters are too cold for it to survive outside. Treat it as an annual, or bring it indoors in a pot before hard freezes arrive in fall. Indoors, it is harder to keep happy than most herbs. Give it your brightest window and a cool room, around 65 degrees or a little below, and keep the soil on the dry side, since overwatering is a common way to lose it. With that care it can go back out in spring.
If you grow rosemary in a container all summer rather than in the ground, moving it inside is simple. In the ground, you either dig and pot it in fall or plan to replace it each season.
Herbs That Prefer Cool Weather
Cilantro is a cool-season herb that bolts quickly once summer heat arrives. In Missoula, plant it in early May and expect it to produce well through June. When July heat kicks in it will go to seed fast. The good news is that you can sow it again in late August for a fall crop, and the seeds it drops in summer often self-sow and come up on their own in fall.
Parsley handles cold much better than most herbs and can be started early in the season. It is technically a biennial, meaning it grows leaves in its first year and goes to seed in its second. In Missoula it often does not survive winter, and a plant that does will mostly go to seed the next year, so most gardeners treat it as an annual. It produces steadily all season without bolting the way cilantro does.
Dill can be direct sown in spring and grows quickly. It tends to bolt in heat but self-seeds readily, so once you have it in your garden it tends to show up again on its own each year. If you want dill for the fronds rather than seeds, successive sowings every few weeks keeps fresh growth coming. For growing vegetables alongside your herbs, the Missoula vegetable growing guide covers the full range of crops that work here.
Basil Needs the Most Attention
Basil is one of the fussier herbs to grow in Missoula, and it is worth knowing that going in. It cannot tolerate frost, does not like temperatures below 50 degrees even on summer nights, and turns black if it gets cold or wet at the wrong moment.
Do not plant basil outdoors until frost danger has passed and the nights have warmed up. MSU Extension suggests soil of at least 55 degrees. In Missoula, that usually means waiting until early June. The Missoula frost dates and planting calendar is worth bookmarking for timing. Even a brief cold night in late May can set the plant back significantly or kill young seedlings outright.
Plant basil in your warmest, most protected spot. Full sun is ideal, and University of Minnesota Extension suggests at least six to eight hours of bright light a day. If you are growing it in containers, move them somewhere sheltered, or indoors, on unusually cold nights.
Pinch flower buds off as soon as they appear, and pinch the growing tips now and then to encourage branching. Pinching delays flowering. University of Minnesota Extension notes that basil allowed to flower and set seed turns woody, yields drop, and the flavor can get more bitter. Regular pinching keeps it producing good foliage longer into the season.
A Few General Notes
Soil needs vary by herb. Mediterranean herbs like thyme, oregano, sage, and rosemary prefer well-drained soil on the leaner side and do better with less fertilizer and less water than most people give them. Leafy herbs like basil and parsley grow best in fertile, well-drained soil with steady moisture.
Containers work very well for herbs in Missoula. They let you move cold-sensitive herbs indoors easily, keep aggressive spreaders like mint contained, and warm up faster in spring than in-ground beds. If you do not have much garden space, a few containers in a sunny spot will grow more herbs than a household typically uses.
If you are tucking herbs in among your vegetables, the guide to companion planting for Missoula gardens covers which pairings have good reasons behind them.
Sources
- Montana State University Extension, Herbs for Montana Gardens
- University of Minnesota Extension, Growing Basil in Home Gardens
- University of Illinois Extension, Rosemary
- USDA Plant Hardiness Zone Map