Skip to main content
Garden & Home Reviews is reader-supported. We earn affiliate commissions from qualifying purchases — how this works.

How Many Tomato Plants in a Grow Bag?

Home/Resources/Raised Beds & Planters/Tomatoes Per Grow Bag
Elena Marsh
Written & researched by Elena Marsh Gardening & Landscaping Editor
Updated October 2026
Close-up detail of the material being worked in a raised beds & planters project, in soft overcast light

Affiliate Disclosure

Some links on this page are affiliate links. As an Amazon Associate, we earn from qualifying purchases — at no extra cost to you. We do not buy, test, or physically handle the products we cover; our rankings come from aggregated owner reviews, ratings and expert consensus. Commissions never change our verdicts. How we rank · full disclosure.

Plant one tomato per 10-gallon grow bag. That is the working rule, and it holds for nearly every variety sold in a garden center. A 5-gallon bag supports a single compact determinate or patio type. A 15 to 20-gallon bag comfortably carries one indeterminate through a full season without daily watering. Two plants in a 10-gallon bag is the most common mistake in container tomato growing: the pair competes for the same water and nitrogen, both stay stunted, and the combined harvest typically comes in below what one uncrowded plant would have given you.

What size bag does each type of tomato need?

Cooperative extension guidance on container vegetables converges on 5 gallons as the absolute floor for a tomato and 10 or more as the practical recommendation, and owner experience in fabric bags matches that closely. Fabric breathes, which is why bag sizing runs slightly larger than the equivalent plastic pot.

Bag sizePlantsSuits
3 gallon0Too small for tomatoes; herbs only
5 gallon1Patio and dwarf determinates only
7 gallon1Standard determinate, comfortably
10 gallon1Any indeterminate; the default choice
15 gallon1Vigorous indeterminate, less watering
20–25 gallon1–2Two determinates works; two indeterminates still crowds
Close-up detail of the material being worked in a raised beds & planters project, in warm late-afternoon light

Why does crowding cost you so much yield?

Three mechanisms, and they compound. First, water. A bag holds a fixed volume of available moisture; two plants draw it down in half the time, so the mix swings between wet and dry far more sharply. Second, calcium. Blossom end rot is a calcium transport failure driven by inconsistent moisture rather than by a shortage of calcium in the mix, which is why it appears in crowded containers even where the grower has added lime. Third, light and airflow. Two vines in one bag shade each other, and the still, humid air inside a dense canopy is exactly the condition early blight and septoria leaf spot need.

Fabric bags magnify the water issue relative to plastic because they lose moisture through the sidewalls as well as the surface. That evaporation is the same property that air-prunes roots and prevents circling, so it is a feature, not a defect, but it means volume matters more, not less.

Wide view of a person's hands pressing seedlings into dark soil in a timber raised bed, in soft overcast light

How far apart should the bags themselves sit?

Set 10-gallon bags 18 to 24 inches apart, measured rim to rim, for indeterminates on stakes. That gives enough airflow to keep foliar disease down while still letting the bags shade one another at soil level, which reduces evaporation on hot afternoons. Determinates in 7-gallon bags can go 15 to 18 inches apart. If you are running a row along a fence, give the row a north-south orientation so both sides of each plant get sun through the day.

Golden-hour view of a person's hands pressing seedlings into dark soil in a timber raised bed

What else decides whether one plant thrives?

Volume is the first constraint, but the mix is the second, and garden soil in a grow bag will compact and defeat everything else you do — the correct blend is covered in what to fill grow bags with. Beyond that, stake or cage every plant at planting time rather than after it flops, feed with a balanced fertilizer once flowers set rather than pushing nitrogen all season, and mulch the surface of the bag with an inch of straw or shredded leaves to slow evaporation.

If you are still choosing a size, what size grow bag for tomatoes goes into the volume question in detail, and our best grow bags roundup ranks the fabrics owners report holding up longest under a full-season tomato.

We never buy, test or physically handle the products we rank. Recommendations come from aggregated owner reviews, star ratings, review volume and expert consensus — see how we rank.

More from this hub: Raised Beds & Planters · Best grow bags · Grow bags vs plastic pots · How long grow bags last · How we rank

Straight Answers

Frequently Asked

Can you put two tomato plants in a 10-gallon grow bag?

You can, and gardeners do it every year, but the combined harvest is usually smaller than one well-fed plant would have produced. Two root systems in 10 gallons of mix compete for the same water and nutrients, so both plants stay smaller, both need watering roughly twice as often in July, and blossom end rot becomes far more likely because calcium uptake fails whenever the mix swings between saturated and dry. If you only have one bag and two seedlings, plant the stronger one and give the other away.

How many cherry tomatoes fit in one grow bag?

One. Cherry varieties are almost all indeterminate and are among the most vigorous tomatoes grown, routinely reaching 6 to 8 feet on a stake. A single Sungold or Sweet Million in a 10-gallon bag will out-produce two crowded plants in the same bag by a wide margin. The exception is the genuinely dwarf patio cherries sold as container types, where two in a 15-gallon bag is workable.

What can you plant alongside a tomato in a grow bag?

Shallow-rooted herbs and a lettuce or two, planted at the rim where they will not fight the tomato for the center of the root zone. Basil is the traditional partner and works because it is harvested continuously and never gets large. Avoid anything with a substantial root system of its own, and avoid a second fruiting crop such as a pepper or eggplant, which competes on exactly the same schedule and for the same nutrients.

Do determinate tomatoes need less space than indeterminate?

Yes, meaningfully. A determinate variety grows to a genetically fixed height, commonly 3 to 4 feet, sets its fruit over a two to three week window and then stops. That shorter growth period and smaller frame means a 5-gallon bag is workable and a 7-gallon is comfortable. An indeterminate keeps growing and fruiting until frost, so it builds a much larger root system and wants 10 gallons minimum.

Why do my grow bag tomatoes wilt every afternoon?

Almost always insufficient volume relative to plant size, not a disease. A mature indeterminate tomato in full sun can transpire several quarts on a hot day, and a 5-gallon bag simply does not hold that much available water. Fabric bags also lose moisture through their sidewalls, which is the trade-off for the aeration that makes them good. The fixes are a larger bag next year, mulch on the surface, grouping bags so they shade each other, and watering morning and evening in peak summer.