Missoula Soil Delivery

How much soil do I need to fill my raised garden beds before planting?

For raised beds in Missoula, you want to fill them completely with a quality garden soil blend rather than using native silt loam, which will compact in a raised bed environment and underperform. Measure the length, width, and depth of your raised bed in feet, multiply all three numbers together, and then divide by 27 to convert cubic feet to cubic yards. A standard 4-foot by 8-foot bed that is 12 inches deep requires about 1.2 cubic yards of soil. Ordering a little extra is always a good idea since soil settles after watering.

Is it too late in the season to add soil to my yard if I order in August?

August is actually a workable time for soil delivery in Missoula as long as you keep your goals realistic. For lawn repairs or overseeding, you want to target late August through mid-September so the grass seed has time to germinate before the first frost around September 25. For garden bed building or raised bed filling, August is a perfectly fine time to work since you can get the beds amended and ready for a fall planting of garlic or cover crops. Just plan your project with the September frost date in mind.

Will the soil I order stay workable in the fall or does it freeze solid before I can finish?

Missoula's fall temperatures cool quickly after the first frost in late September, but the ground typically does not freeze hard enough to prevent digging until mid to late November depending on the year. This gives you a reasonable window to finish soil projects into October. If you are planning significant grading or bed building, targeting a delivery in September is the safest approach so you have maximum working time before the ground locks up for winter. Soil piles themselves can freeze on the exterior but usually stay workable in the center if used promptly.

Can I mix the delivered soil into my existing silt loam or should I keep them separate?

Mixing is almost always the better approach for Missoula landscapes unless you are building a raised bed with a solid barrier between the new soil and the native ground below. When you integrate quality topsoil or amended garden soil into your existing silt loam, you improve the structure of the native soil over time rather than creating a hard transition layer that roots struggle to cross. Till or spade the two together to at least 6 inches deep for the best results, especially in vegetable gardens and perennial flower beds.

Does the soil from MulchMound already have fertilizer in it or do I need to add that separately?

Our garden soil blends contain organic matter that provides some baseline fertility, but they are not pre-loaded with synthetic fertilizers. For Missoula vegetable gardens, we recommend adding a balanced slow-release organic fertilizer at planting time and then side-dressing with compost midseason, particularly since the short growing season at this elevation does not leave much room to recover from a slow nutritional start. For lawn applications, a soil test from the University of Montana Extension office can tell you exactly which nutrients your specific property needs before you invest in amendments.

I am planting a new lawn from seed and my slope washes in heavy rain. Will delivered topsoil make that worse?

Slopes around Missoula, especially on the drier south and west-facing hillsides, are prone to erosion from the occasional heavy summer storm even in a relatively low-rainfall climate. Fresh topsoil on a slope is vulnerable until grass roots establish, which takes at least 4 to 6 weeks under ideal conditions. To reduce washout, apply the topsoil in a thin layer no deeper than an inch over the existing grade for lawn seeding, use erosion control blankets or straw on steeper sections, and water lightly and frequently rather than deeply until germination occurs.