Container-crop planning disagreement ledger

Dataset Last checked 26 October 2026

Published container-size advice differs by crop, variety and planting arrangement, so one number should not stand in for every source. This ledger joins twenty crop groups across five extension services and preserves their original volumes, depths and conditions. Use it to find the advice that matches your proposed planting, then read the source before choosing a container.

Read a row without losing its conditions

The table is a compact view of the source observations. Maryland lists minimum container volumes for common vegetables¹. Illinois pairs container sizes with planting densities and named varieties². NC State’s table combines minimum volume, spacing and depth, while its surrounding text describes minimum size per plant³. Wisconsin groups named examples into smaller and larger plants⁴. UC’s depth tables report soil depth; a separate table gives container alternatives⁵.

Those are different descriptions of a planting. A pair of unequal numbers earns a difference flag, not a declaration that either service is wrong. A pair of equal numbers does not establish agreement about plant count, light or variety. No average, winner or universal minimum is calculated.

Crop	Maryland volume	Illinois volume	NC State volume	Wisconsin volume	UC volume option	UC soil depth	Different volumes
Bush beans	2 gallon	One gallon†	2 gallon†	minimum 5 gallons	2–5 gallon†	16–18 inches†	Yes
Beets	½ gallon	Two gallon	2 quart	–	–	9–12 inches	Yes
Carrots	2 gallon	Two gallon	2 quart	–	–	9–18 inches; depends on carrot length	Yes
Leaf lettuce	½ gallon	One gallon	2 quart†	at least 2 gallons	–	9–12 inches	Yes
Peppers	5 gallon	Two gallon	2 gallon	minimum 5 gallons	2–5 gallon	12–16 inches	Yes
Cabbage	5 gallon	One gallon	–	–	–	12–14 inches	Yes
Cucumbers	5 gallon	One gallon	1 gallon	minimum 5 gallons	2–5 gallon	16–18 inches	Yes
Eggplant	5 gallon	Two gallon	5 gallon	minimum 5 gallons	2–5 gallon	12–16 inches	Yes
Spinach	–	One gallon	1 gallon	at least 2 gallons	–	9–12 inches	Yes
Swiss chard	2 gallon	One gallon	2 quart	–	2–5 gallon	9–12 inches	Yes
Cherry/patio tomatoes	2 gallon†	One gallon	5 gallon†	minimum 5 gallons†	2–5 gallon†	12–16 inches†	Yes
Standard tomatoes	5 gallon	Three gallon	5 gallon†	minimum 5 gallons†	2–5 gallon†	16–18 inches†	Yes
Radishes	1 pint	Two gallon	2 quart	at least 2 gallons	–	9–12 inches	Yes
Summer squash	10 gallon	–	2 gallon†	minimum 5 gallons†	2–5 gallon†	16–18 inches	Yes
Parsley	5 gallon or larger‡	Half-gallon	–	–	–	–	Yes
Bok choy	–	–	1 gallon	–	–	–	Too few values
Collards	–	–	3 gallon	–	–	–	Too few values
Green garlic	–	–	2 quart	–	–	–	Too few values
Kale	–	–	3 gallon	–	–	–	Too few values
Mustard greens	–	–	3 gallon	–	–	–	Too few values

† A broader crop group or narrower subset was matched; see each record’s scope. Volumes retain the source unit. A dash means the selected source section gives no volume figure; it is not zero or a claim that the crop is unsuitable. UC depth is soil depth. Generic crop matches remain qualified in the full records.

Maryland qualifies its vegetable table: bush, dwarf and compact varieties can use smaller containers than full-size counterparts¹. This matters for cucumbers and both tomato rows; Illinois’s one-gallon cucumber row names bush varieties². The full records retain those conditions without changing the volume figures.

‡ Maryland lists parsley with large herbs needing 5 gallons or more, but also names it among small herbs for Salad Tables and Salad Boxes¹. Both contexts remain attributed; no replacement volume is inferred.

Follow the leaf-lettuce example

Maryland lists half a gallon for leaf lettuce. Illinois lists one gallon together with four to six plants and a selection of varieties. NC State’s generic lettuce entry gives two quarts, four to five inches of spacing and six to eight inches of container depth. Wisconsin includes leaf lettuce in its smaller-plant examples with a minimum two-gallon container and four to six inches of depth. UC gives nine to twelve inches of soil depth in its shallow-container group.

Start by identifying the planting you actually intend. A container for several lettuce plants is not automatically equivalent to a minimum stated per plant. The Illinois density is part of the record, not a detail to discard when comparing gallons. The NC State row is broader than leaf lettuce alone, so the join records that broader match instead of silently treating it as a variety-specific recommendation.

Next, keep volume and depth separate. A deep, narrow container and a shallow, wide container can hold the same volume. This ledger does not turn a depth into gallons or infer an unreported diameter. Finally, follow the source link for the growing context. The table is a navigation aid to documented advice, not a substitute for checking your own location and crop variety.

Understand a missing cell

Every one of the twenty crop groups has a place in each source comparison, including when the selected table has no entry. A missing value stays null in the JSON. The record states which section was checked and preserves any crop-name limitation. Missing is different from an explicit zero, a prohibition or a failed growing trial.

For example, a source may discuss a crop elsewhere without giving it a minimum-volume row. That does not authorize copying a nearby crop’s number into the empty cell. Nor does the presence of a generic tomato row prove that the same advice covers every patio variety. The comparison records the available match and its limitation, leaving the reader able to inspect it.

Use the complete records

The canonical JSON edition keeps the source URL, UTC observation date, source section and original condition with each factual cell. The CSV export is a flattened view for sorting and comparison. Text cells that could be read as spreadsheet formulas are protected; empty CSV values correspond to nulls in the JSON, where the reason and source scope remain available.

The method explains crop matching, the limited volume normalization and the automated second check. The source ledger identifies the five pages and their dates. Read the CC BY 4.0 licence when reusing this original compilation.

Only an explicitly stated volume is eligible for a volume conversion. A range stays a range. A named variety stays attached to its source. Revisions should retain the previous edition and identify changed cells, rather than making an old comparison appear to have used new advice. The observed date says when a page was checked, not when its recommendation was first published or experimentally established.

Turn a comparison into a planning question

Write down the crop, variety if known, intended plant count, stated container capacity and available depth. Compare that record with one source at a time. Where a necessary detail is missing, keep it as a question instead of borrowing an answer from another service. The small container-garden guide offers a complete planning worksheet for that next step.

Not covered on this page

Growing trials, measured yields or proof that a minimum will suit every location.
Structural loads, container treatment or pest-control instructions.
Unreported variety equivalence or a recommendation to average conflicting figures.

Sources

University of Maryland Extension, Growing Vegetables in Containers and Salad Tables. Updated 10 September 2026; accessed 26 October 2026 UTC. ↩ ↩² ↩³
Illinois Extension, Growing Vegetables in Containers. Publication date not stated in the checked page; accessed 26 October 2026 UTC. ↩ ↩²
NC State Extension, Plants Grown in Containers, Table 18–1. Published 1 February 2022; accessed 26 October 2026 UTC. ↩
Wisconsin Extension, Growing Vegetables in Containers. Revised 17 February 2021; accessed 26 October 2026 UTC. ↩
UC Master Gardener Program of Contra Costa County, Growing vegetables in containers. Dated 25 April 2026; accessed 26 October 2026 UTC. ↩

How we test: methodology. Found a mistake? Corrections.