This page cannot give you a pest calendar, because the sources behind it do not publish one. What they do document is what an asparagus bed takes from a Montana garden over a decade or more: ground that drains, a steady supply of water, and a planting window in early spring. I won’t invent an insect timetable to fill the gap. The pest question gets its own plain answer near the end.
The short answer
An asparagus bed is a long commitment. Utah State University Extension, the only authority used here, puts the bed’s productive life at 10 to 15 years, and nothing is harvested until year 3. The soil requirement it states is short: most soils will do, provided they are well drained. That one condition carries a lot of weight, because every other choice in the bed sits on top of it. Elsewhere in the garden, a heavy soil is a nuisance you amend each season. Here, a bad spot is a decision you live with for fifteen years. (More on the groundwork is in Will Montana Soil Hold an Asparagus Bed for Fifteen Years?)
Montana’s official state soil is the Scobey series, named by state law. It is a Mollisol, the deep, dark prairie type of ground that built the Corn Belt. USDA’s representative values for its surface layer read like this: about 35 percent sand, 31 percent clay and 34 percent silt, which USDA classes as clayey, with organic matter around 2.0 percent and a surface pH of about 7.0, near neutral. The detail that matters for asparagus is the drainage class. Scobey is recorded as well drained. On that evidence, the ground that represents Montana meets the one requirement the source sets.
The pH figure describes the series, not your garden, and the asparagus source gives no pH target of its own. Don’t read the 7.0 as a green light or as your own number. A soil test settles that.
The caution is just as plain. The Scobey series stands for the state, not for every yard in it. Montana spans hundreds of soil series, and river bottoms, hill country and any lot a builder has scraped or filled can behave nothing like it. A clayey surface that drains well in a mapped prairie profile can still sit wet where a bulldozer has packed the subsoil. So treat the state soil as a starting guess about what the region’s ground tends to do, and check your own plot before you dig.
If the spot does not drain, you have three honest options:
- Move the bed to higher or looser ground on the same property, even if it is less convenient.
- Build it up above the surrounding grade, so water has somewhere to go.
- Give up on asparagus there and plant an annual crop that tolerates the spot, since annuals can be amended or abandoned each year and a bed cannot.
To find out which situation you are in, dig a test hole where the bed would go, fill it with water, and watch how long it stands. Water that lingers is your answer before a single crown goes in. For the overall picture of the crop, start with Growing Asparagus in Montana.
Will the summer here water it for you?
Not on its own. The bed wants 1 to 2 inches of water every other week for its first two years, then every three weeks after that. Billings, the NOAA reference station for these figures, averages about 4.3 inches of rain across June, July and August, out of 14.3 inches for the whole year. Those are normals, meaning what the region can usually expect, not a forecast and not a reading from your garden. Here is how to turn them into a watering plan.
- Read the monthly numbers against the dose. June averages 2.22 inches, July 1.22 and August 0.87. August’s average rainfall for the entire month is less than the smallest single watering the bed is asking for. June, by contrast, could in a good year cover a full dose on its own. The summer is front-loaded, and the bed’s thirst is not.
- Put a rain gauge on the plot. A normal is an average of wet and dry years, and a slope, a rain shadow or a city lot shifts it. A cheap gauge tells you what actually landed, and that decides whether this week’s watering is needed. Rain that arrives as one summer thunderstorm tends to run off instead of soaking in, so a big number on the gauge from a single storm counts for less than the same total spread over several days.
- Add the difference, every other week, in years one and two. Count a week’s rain toward the 1 to 2 inches, then top up by hand or with a soaker line. In a typical Montana summer the gardener supplies most of the water, especially from July onward, when the monthly averages fall below the dose.
- Let the soil adjust your timing. The same inch behaves differently on different ground. A clay surface holds it for about a week, a sandy one passes it through within the day. A heavy bed may stay moist longer between waterings. A sandy patch may need more frequent, lighter attention even in a wetter stretch.
- Stretch to every three weeks from year three. That is also when harvest begins. The bed’s schedule relaxes just as the plant starts paying you back, but the dry stretch of late summer still needs watching on any bed that is not draining slowly.
When to put the crowns in
Early spring, and in Montana that phrase needs an anchor. NOAA’s most recent climate normals for Billings put the last spring freeze at around April 29 to May 10. That is the band where freezing temperatures at 32°F are still between 30 and 70 percent likely, so it describes the toss-up, not a safe date. A mean frost date is an average, and any given year can land on either side of it. The NOAA station data sits behind the figure.
Billings is also one of the milder valleys. Mountain valleys elsewhere in Montana can frost in any month, so a gardener at higher elevation should treat that window as optimistic and watch local conditions before committing a planting day. The related question of timing is covered in When to Plant Asparagus Crowns in Montana.
The planting method itself is specific. Crowns go into furrows 8 inches deep. The furrow is not filled in at once. It gets backfilled gradually across the year, 2 inches every other month, which is a slow close that matches the plant’s growth.
Then comes the patience. Nothing is harvested until year 3. After that the schedule is four weeks of picking, then six the next year, then eight. The rule for ending each season is an object, not a date: stop when most of the spears are thinner than a pencil. A bed that is cut past that point is being drained of what it needs for the following year.
Four varieties appear in the source, listed with only their sex. Jersey Giant and Jersey Knight are all-male. UC 157 F1 and Purple Passion are male and female. The source publishes no flavor, yield or reason to prefer one over another, so I won’t offer one.
Seed is the alternative route to crowns. The verified facts here carry no seed-starting dates, so there is no Montana seed calendar on this page. If you go that way, follow the instructions on the seed packet and keep the spring frost window above in mind.
Common questions
What eats asparagus in Montana, and when?
No pest timetable is published in the sources behind this page, so there is no honest answer here to the “when.” For insects and animals active in your county, your county Extension office is the right next call. The guidance in this page concerns the bed itself: drainage, water and timing.
How long before I can pick spears?
Nothing is harvested until year 3. The harvest then runs four weeks, then six, then eight, and the bed goes on producing for 10 to 15 years. Taking “just a few spears” earlier is not what the source recommends.
Is clay too heavy for asparagus?
Clay is not the problem. Poor drainage is. The state soil, Scobey, is clayey yet recorded as well drained, but your own ground may differ. Test it with a water-filled hole before planting, and build up the bed or move it if water stands.
How should I store cut spears?
UC Davis Postharvest gives the target as 32 to 35°F with 95 to 100 percent relative humidity. Above 50°F, spears toughen within hours. At about 31°F or lower, they freeze and collapse when thawed. In a home kitchen, standing the cut ends in water or wrapping them damp is the practical way to hold that humidity, since spears lose water through the cut end faster than anywhere else.