Growing Strawberries in Containers: Guides Say 6 to 18 Inches Deep, but the Root Data Fits 8 to 12

Look up how deep a strawberry pot should be and the answers differ by a factor of three. Oregon State Extension says 10 to 18 inches. Iowa State Extension says 8. One popular gardening site starts its range at 6 to 8. Each number is stated flatly, and on the pages we read, none cites the root measurement behind it.

Those measurements exist. Strawberry roots are shallow, but “shallow” in the field studies spans 6 to 12 inches rather than one number, and a pot’s width, not its depth, decides how many plants it can carry. The sections below set the depth advice against the root data, then run a pot-volume calculation of our own to show what depth does and does not buy you.

What the guides say about pot depth

Published depth advice for strawberry containers runs from 6 inches to 18, and the two extension services that give a depth (8 inches and 10 to 18) disagree as much as the commercial guides do. Depth is the figure most readers copy, so the spread matters.

Skip the guesswork — get a pre-planned 4×8 kitchen garden bed

Free printable planting plan: what goes where, when to plant it, and how to keep it alive. Plus two bonus flower bed plans.

Send me the plans

I agree to receive emails from Blooming Expert and accept the Privacy Policy. Unsubscribe anytime.

Iowa State gives its reason in one sentence: “Because strawberries are shallow-rooted, containers do not have to be deep.” Oregon State’s reason is “sufficient root production.” Neither page cites a measurement, so to judge the numbers we need the measurements themselves.

Where strawberry roots sit in the ground

In field soil, between half and nine-tenths of a strawberry plant’s root volume sits in the top 6 inches, and the sources we found put the working root zone at 6 to 12 inches. The table lists what each source measured or states.

Every source puts roots near the surface. They disagree by a factor of two on how far down “near” goes, from 6 inches in clay loam to 12 in Utah’s and Pires et al.’s figures. The UW–Madison depth chart is the most useful because it shows the spread instead of one number: from 6 to 12 inches it places between 10 and 50% of the roots.

The same bulletin gives a mechanism for the layering. The crown elongates upward as the plant grows and tends to “grow out” of the soil, and new roots form progressively higher on it. Its depth chart labels the 0 to 3 inch layer as the youngest roots and the 6 to 12 inch layer as the oldest.

Two cautions apply. First, the split is not fixed: Penn State ties its 90% figure to heavier soils such as clay loams, and the UW–Madison range of 50 to 90% shows the share moves. Second, every figure above comes from field soil. We found no strawberry root measurement made in potting mix, so how roots split inside a pot is unmeasured. Treat these numbers as a guide to the pot, not a spec for it.

Reading the depth advice against the root data

An 8-inch pot covers the top 6 inches that hold most roots plus 2 inches of margin; 10 to 12 inches reaches the deepest zone any source above names; 18 inches goes past all of them. That is our reading of the sources, not a measured pot trial.

The rule that falls out: 8 inches is the floor, 10 to 12 inches is the comfortable range, and past 12 you are buying soil. Our own guide to the best pots for strawberries uses the same 8-inch floor for the same reason.

Width sets how many plants a pot carries

Surface area, not depth, decides how many strawberry plants a pot holds: Iowa State spaces plants about 8 inches apart and fits 3 or 4 in a 12-inch pot. UW–Madison Extension adds that long, narrow containers out-produce round ones, which points the same way: more surface, more crowns.

We computed the mix volume of common container shapes and divided it by plant counts that follow Iowa State’s 8-inch spacing (one row in the window box, one plant in the 8-inch pot, in line with EarthBox’s chart of one plant per 6 to 8 inch pot). The volumes assume straight sides, so a real tapered pot holds less. Treat each as an upper bound.

A tall 8 × 14 pot and a 12 × 8 pot hold about the same mix (11.5 and 14.8 liters), yet the wide pot carries 3 or 4 plants and the tall one carries one. The calculation also shows volume is not the binding number at recommended widths. Ohio State’s controlled-environment guidance sets a minimum of 2 liters of substrate per strawberry plant, and every pot above clears it. That figure comes from greenhouse soilless production, so use it as a floor reference only.

Volume still counts at the other end. A 2017 paper on ‘Elsanta’ strawberries grown without soil, by Massetani, Savini and Neri, reported that total plant production was similar across substrates and container types, but plants in higher-volume pots gave more fruit than plants in smaller pots. Trimming volume to save on mix may cost fruit. The cheap way to add volume is width, which also adds plant sites.

What depth changes in a pot: water, air and winter

In a pot, depth changes the balance of water and air in the mix. Greenhouse Grower, reporting an NC State e-GRO alert by Brian Whipker and Patrick Veazie, explains the mechanism: after irrigation, short pots tend to hold a perched water table, a saturated layer at the bottom. Taller pots add air space and often hold less water, and a short pot filled with a fine substrate can end up with too little air, which invites root rot.

Strawberries are exposed on both sides of that trade. Penn State links the shallow root system to the plant’s sensitivity to both water deficit and excess. Iowa State warns that strawberries do not tolerate dry, hot conditions and may need watering daily, twice daily in summer heat. UW–Madison notes that container plants dry out faster than plants in the ground.

The practical result for a shallow pot is a coarse, free-draining mix. Oregon State’s recipe is one part perlite, one part finely ground fir bark and two parts garden or potting soil, and it stresses that both the mix and the container must drain well. Our walkthrough on how to fill a strawberry pot covers planting height and watering once the mix is chosen. That a deeper pot lowers the risk of a soggy bottom follows from the e-GRO mechanism, but nobody has tested it on strawberries, so read it as inference.

Winter is where depth does not rescue you. Iowa State does not recommend overwintering strawberries grown in containers and suggests composting them at the end of the season. For June-bearing types only, it describes digging the container into the soil under at least 6 inches of straw, and even then calls them highly prone to winter damage or death.

Which container should you choose?

Pick the container by width first, then check that the interior depth reaches at least 8 inches. Measure the inside of the pot, not the outside.

• If you want one safe rule, choose a pot 12 inches wide and 8 to 12 inches deep and plant 3 strawberries. That sits at Iowa State’s floor and inside our reading of the root data.
• If your summers are hot or your mix is light and fast-draining, choose the 12-inch depth: more mix in total, and a taller column is less prone to a soggy bottom. This is our inference from the water-balance mechanism, not a measured result.
• If all you have is a 6-inch window box, treat it as a stopgap: 3 plants at most, daily watering, and the knowledge that field data put up to half the roots below 6 inches.
• If you own a tall, narrow pot, plant one strawberry in it, or buy a wide planter for several.
• If a guide tells you 10 to 18 inches, treat the top of that range as optional. None of the root sources we found puts the working root zone that deep.

The pot is half the decision; the plant is the other half. Our guide to choosing the right strawberry variety for pots and hanging baskets covers which cultivars suit a container. For the wider picture, start from the strawberry growing guide.

Frequently asked questions

How deep should a container be for growing strawberries?

At least 8 inches deep and 12 inches wide, with 10 to 12 inches deep as the comfortable range. Iowa State Extension gives 8 inches as the floor, and field root studies put most roots in the top 6 to 12 inches.

Do strawberries need a deep pot?

No. Strawberries are shallow-rooted, and Iowa State states that containers do not have to be deep. The sources we found put the working root zone at 12 inches or less, so as far as they show, pots deeper than that add mix rather than roots.

Can strawberries grow in a 6-inch-deep pot?

They can survive, but a 6-inch pot stops where the layer that holds 10 to 50% of the roots in the UW–Madison depth chart begins. Expect less margin, so water daily and keep to three plants at most.

How many strawberry plants fit in a 12-inch pot?

Three or four. Iowa State spaces plants about 8 inches apart and fits 3 or 4 in a 12-inch container; Oregon State allows up to four.

Is a wide pot better than a deep pot for strawberries?

For strawberries, yes. Iowa State calls relatively large containers with a lot of surface area best, and UW–Madison reports that long, narrow containers produce more heavily than round ones. In our calculation a wide 12 × 8 pot carries 3 or 4 plants on a similar volume of mix (about 15 L against 11.5 L for a tall 8 × 14 pot, which carries one).

Can you leave strawberries in containers over winter?

Iowa State does not recommend it. It suggests composting container strawberries at the end of the season, and says even June-bearing plants dug into the ground under straw are highly prone to winter damage or death.

Sources

1. Iowa State University Extension and Outreach. How to Grow Strawberries in Containers. Yard and Garden. Iowa State University
2. Oregon State University Extension Service. Growing berries on the Oregon Coast: Strawberries (EM 9178). Oregon State University
3. University of Wisconsin–Madison Division of Extension. Growing Strawberries in Containers. Horticulture. University of Wisconsin–Madison
4. Smith BR, Mahr DL, McManus PS, Roper TR. Growing Strawberries in Wisconsin (A1597). University of Wisconsin–Madison Extension
5. Penn State Extension. Growing Strawberries. Pennsylvania State University
6. University of Connecticut Home and Garden Education Center. Strawberries. University of Connecticut
7. Kansas State University Research and Extension. Strawberries (MF598). Kansas State University
8. Utah State University Extension. How to Grow Strawberries in Your Garden. Utah State University
9. Pires RC de M, Folegatti MV, Passos FA, Ambrosano GMB, Minami K (2000). Effective depth of strawberry radicular system under different soil covers and water levels. Pesquisa Agropecuária Brasileira 35(4):793–799
10. Massetani F, Savini G, Neri D (2017). Effect of substrate and container type in the strawberry soilless cultivation. Acta Horticulturae 1156:295–300. DOI 10.17660/ActaHortic.2017.1156.45
11. Ohio State University, Ohio Controlled Environment Agriculture Center. Production Systems: Substrate Systems. Ohio State University
12. Greenhouse Grower. How Does Pot Height Affect Water Holding Capacity? 28 May 2024 (reporting the NC State e-GRO alert by B. Whipker and P. Veazie)
13. Old Farmer’s Almanac. Growing Strawberries in Containers: A Natural Fit for Pots
14. Epic Gardening. 15 Tips For Growing Strawberries in Pots or Containers
15. EarthBox. Growing Strawberries in Containers: A Step-by-Step Guide