Growing Tomatoes in 5-Gallon Buckets: A Full Bucket Holds Only 1 to 2 Gallons of Usable Water, So Drill and Water for It

A 5-gallon bucket will grow a tomato, but only the right kind of tomato, and only if you plan around water rather than space. Extension sources put five gallons at the floor for a standard plant, and they agree on what fits: determinate and compact types do, vining types outgrow it. What gives out first is not root room. It is the water the mix can hold between waterings.

This guide covers which plants fit, how to choose and drill the bucket, how much usable water five gallons of mix really holds, what to do about watering and calcium, and how to convert one bucket into a self-watering planter.

Which Tomatoes Fit in a 5-Gallon Bucket?

Determinate and compact varieties fit; indeterminate vines do not. Wisconsin Extension says a tomato that keeps growing all season needs a container bigger than a 5-gallon bucket, while the smaller determinate varieties “can be grown in a 5 gallon bucket.” Clemson adds that indeterminate cultivars “will continue growing taller until frost, making them difficult to grow in containers.” Plant one per bucket: NC A&T and Virginia Tech both say one plant per container.

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The takeaway: these sources treat five gallons as the working floor for a standard tomato (Virginia Tech allows 1 gallon for cherry types), and only determinate, patio or cherry types stay comfortably inside it. For named varieties, see our 8 patio tomato varieties for 5-gallon containers, and for the growth habit itself, our guide to determinate versus indeterminate tomatoes.

Choose a Light-Colored, Food-Grade Bucket

Use a light-colored, food-grade bucket that has never held anything toxic. Auburn Extension says to make sure the bucket is food-grade plastic and not previously used for storing toxic materials, and Virginia Tech says a container must never have held products toxic to plants or people. Bakeries, delis and restaurants often give away food-grade buckets, according to University of Maryland Extension.

The safety research behind “food-grade” is thin. An OSU Extension answer on Ask Extension calls it “a complex question with very few good (unambiguous) answers,” says food grade is “probably” safest, and adds that such plastics have probably never been tested with soil interactions. The same answer notes that standard hardware-store buckets “aren’t terribly sun-stable.”

Color matters for a different reason: heat. NC A&T tells growers to pick light-colored plastic because dark containers hold excess heat, which can raise soil temperature and possibly damage roots in summer. USDA-ARS nursery trials reported in Digger magazine measured substrate in black plastic containers up to 30°F above air temperature, with peaks of 133°F in McMinnville, Tennessee, and lower maximum root-zone temperatures in white ones. That work used nursery plants, not tomatoes, and we found no tomato trial, but it matches the extension advice. If your only bucket is orange or black, Wisconsin Extension suggests a spot that gets some shade during the hottest part of the day.

Drill the Drainage Holes (and Skip the Gravel)

Drill holes in the base about every 3 inches, then lift the bucket so it does not sit in its own runoff. Auburn’s instruction is to “drill or punch holes every 3 inches into the bottom of the bucket.” Round plastic buckets run about 11 to 13 inches across on the outside and 14 to 15 inches tall, according to supplier The Cary Company. Buckets taper toward the base, so measure your own floor: if it is 10 inches across, 3-inch spacing takes roughly seven to nine holes (our arithmetic: a ring plus one in the center, or a loose grid). The extension pages we read give spacing and position but no bit size. Illinois Extension says small holes drain well and lose very little mix, and that a coffee filter over a hole is optional.

1. Mark a ring of dots and one center dot on the outside of the base, 3 inches apart.
2. Turn the bucket upside down on a scrap board and drill each dot straight through.
3. Clear the plastic shavings and rinse the bucket.
4. Set the bucket on bricks or pot feet. Virginia Tech warns that a pot “should never be in direct contact with the drainage water,” because it is absorbed back and keeps the soil too wet.

Drilling holes does not make the mix drain dry. Holes let gravity water leave; they do not release the water the mix holds against gravity. Bilderback and colleagues define container capacity as the share of volume a substrate holds at drainage, and put it at 45 to 65 percent for commercial potting substrates, measured in 3-inch cores; the paper notes that container height changes the figure. So a freshly drained bucket still holds a large share of its volume as water, and that is the point of the next section.

The same logic explains why a gravel layer under the mix is not the fix it sounds like. Washington State University’s Linda Chalker-Scott writes that “drainage material added to containers will only hinder water movement,” because water will not move from a fine soil into coarser material until the fine soil is saturated. Illinois Extension calls the gravel layer a myth for the same reason. Auburn, by contrast, says a 2- to 3-inch layer “may also promote good drainage,” so extension advice splits. A 2025 PLOS ONE experiment in 175 mm pots found that for loamless organic media almost all drainage layers reduced overall water retention, but it did not test plant growth and says it cannot predict whether a plant benefits.

In a bucket the deciding cost is depth. A 2- to 3-inch layer in a bucket 14 to 15 inches tall removes roughly an eighth to a fifth of the height you can fill with mix (our arithmetic), and mix volume is the scarce thing here. We would skip gravel and, if mix washes out, use a screen or coffee filter instead.

One variation: for larger containers, Wisconsin Extension suggests putting the holes a few inches up the side wall, which leaves a reservoir the roots can use. Maryland’s self-watering design goes furthest, with no bottom holes at all and one overflow hole 2 inches up (see below).

The Volume Math: What 5 Gallons of Mix Really Holds

A full bucket holds roughly 1 to 2 gallons of water a tomato can actually use (0.9 to 1.75 by the working below), which is why buckets dry out so fast. Here is the working, using published figures.

Mix volume. Wisconsin Extension’s bucket recipe calls for one 25-quart bag of soilless mix and leaves 1 inch of space at the top after the first watering; Virginia Tech says to fill to within 1 to 2 inches of the top. A 5-gallon bucket is 20 quarts and the mix sits below the rim, so our estimate of the working volume is 4 to 5 gallons. Maryland fills its modified bucket with about 4 gallons.

Usable water. Bilderback and colleagues give a normal range of 23 to 35 percent of the substrate’s volume as available water, meaning water the roots can pull out; the rest is held too tightly. Multiply: 4 gallons × 0.23 is about 0.9 gallon, and 5 gallons × 0.35 is about 1.75 gallons, or roughly 3.5 to 6.6 liters. Those ranges come from commercial nursery substrates, so a bagged peat mix may differ somewhat.

Read the table as a ceiling, not a forecast. It is arithmetic, not a trial, and plants start to stress before the last available water is gone, so real intervals are shorter. It still explains the extension advice: Virginia Tech says watering “daily or even twice daily may be necessary,” and Wisconsin Extension adds that deeper containers can help with water management but “it doesn’t change the need to check them on a daily basis.”

Water, Feed and Calcium Without Overdoing Any of Them

Check the bucket every day in summer, water until it runs out of the holes, and keep the routine steady. Wisconsin Extension’s rule is to water until it drains, then wait until a finger pushed into the mix no longer feels moist. NC A&T says consistency is as important as amount, and that inconsistent watering can worsen blossom-end rot. A layer of mulch helps: Auburn recommends mulch to conserve soil moisture.

For feeding, Clemson suggests a balanced timed-release fertilizer at planting or a water-soluble one weekly, and NC A&T notes the starter charge in potting mix is gone after a few waterings. The full schedule is in our guide to growing tomatoes in containers.

Calcium is the other container trap. The Morton Arboretum says blossom-end rot is a calcium shortage often linked to dry soil, and that container potting mixes may need calcium supplements. Wisconsin Extension’s recipe adds about 1 cup of garden lime per 5-gallon container; read your mix’s label first. Wisconsin also warns that roma-type tomatoes are more susceptible than smaller round ones. Our blossom-end rot guide covers the fruit symptoms in detail.

The second row is the one people miss. Waterlogging in tomato creates low-oxygen conditions at the roots, and a 2024 Journal of Experimental Botany study of a 48-hour waterlogging treatment ties that low-oxygen root zone to leaf epinasty, the downward bending of leaves. Clemson notes that an undersized container drives constant watering and can topple from top-heavy growth, and Wisconsin says to remove plant material and strongly consider fresh media after severe disease.

Convert the Bucket to Self-Watering

Maryland Extension’s 5-gallon design swaps bottom holes for a hidden reservoir and a side overflow hole, and it still needs refilling every day in July and August. Kentucky Extension explains the mechanism for its own tub-based version: plants draw water up by capillary action, and with the water level at the drain hole, capillary action moves water up about 4 inches above it. The Maryland build, with its numbers:

1. Cut a lid so it fits inside the bucket as a separator, and drill 15 holes of 5/16 inch in it so roots can grow through into the reservoir.
2. Stand three 2½-inch sections of 4-inch perforated drain tile on the floor to support the separator.
3. Drill one ¾-inch hole 2 inches above the bottom and push a 6-inch piece of ½-inch tubing through it, under the separator, as the overflow.
4. Raise the bucket 8 inches on bricks or a cinder block and let the tube drain into a milk jug.
5. Fill with about 4 gallons of moistened medium, plant, and add 2 to 3 gallons of water.

Maryland says self-watering containers conserve water and nutrients and make it possible to ignore them for a few days, but in July and August full sun the reservoir takes 1 to 2 quarts every day, so that freedom has limits in peak heat. Pour the water that collects in the jug back in. Two caveats apply. Maryland’s design uses compost as the only medium, so another mix may wick differently. Kentucky also lists limited soil and nutrient capacity as a drawback, so feeding still matters. We found no published trial comparing tomato yield in plain and self-watering buckets; Maryland shows a tomato grown this way but gives no yield data. Wisconsin Extension recommends a reservoir container if you cannot water daily.

Which Setup Should You Choose?

• You can water every day: a plain light-colored, food-grade bucket with bottom holes, on feet.
• You cannot water daily, or blossom-end rot has hit before: build the Maryland self-watering conversion, remembering it still needs daily refills in peak summer sun.
• You want a full-size indeterminate slicer: use a bigger container; our container guide covers sizes.
• Deck or balcony space is tight: compare options in our tomato planter ideas for decks and balconies.

For everything beyond containers, our tomato plant care guide is the place to start.

Frequently Asked Questions

How many drainage holes does a 5-gallon bucket need?

Auburn Extension says to drill holes every 3 inches in the bottom, which, if your floor is 10 inches across, is roughly seven to nine holes by our arithmetic. No extension page we read gives a firm count or bit size, so spacing is the guide.

Can you grow tomatoes in a 5-gallon bucket without drilling holes?

No. Virginia Tech, Georgia, Clemson and NC A&T all call for drainage holes. The one exception is Maryland’s self-watering design, which has a side overflow hole instead of bottom holes.

Should you put gravel in the bottom of the bucket?

The evidence is mixed. Washington State says gravel hinders water movement and Illinois Extension says it does not improve drainage, while Auburn says a 2- to 3-inch layer “may also promote good drainage.” In a bucket 14 to 15 inches tall, the layer costs mix depth, so we skip it.

Can an indeterminate tomato grow in a 5-gallon bucket?

Not well. Wisconsin Extension says indeterminate plants need a container bigger than a 5-gallon bucket, and Clemson says indeterminate cultivars are difficult to grow in containers.

How often should you water tomatoes in a 5-gallon bucket?

Check daily in summer. Virginia Tech says daily or even twice daily may be needed, and Wisconsin says to water again once a finger pushed into the mix no longer feels moist.

Sources

1. UW-Extension, Marinette County. Growing a Tomato Plant in a Container (linked in text)
2. Dowdy S. Better tomatoes start with good growing practices. University of Georgia CAES Field Report, April 15, 2010 (linked in text)
3. North Carolina A&T State University Cooperative Extension. Growing Fruiting Vegetables in Containers: Tomato, Pepper and Eggplant, May 2020 (linked in text)
4. Relf D. Vegetable Gardening in Containers, 426-336. Virginia Cooperative Extension, last revised March 2026 (linked in text)
5. Turner SA. Tomatoes in Containers. Clemson Home and Garden Information Center, April 12, 2022 (linked in text)
6. O’Rear B. Five-Gallon Bucket Supply List, ANR-2663. Alabama Cooperative Extension System, Auburn University, 2023 (linked in text)
7. Chalker-Scott L. The Myth of Drainage Material in Container Plantings. Washington State University Extension (linked in text)
8. Illinois Extension, University of Illinois. Container Drainage Options (linked in text)
9. Rowe A. Effect of drainage layers on water retention of potting media in containers. PLOS ONE 2025;20(2):e0318716 (linked in text)
10. Bilderback TE, Warren SL, Owen JS Jr, Albano JP. Healthy Substrates Need Physicals Too! HortTechnology 2005;15(4):747-751 (linked in text)
11. The Morton Arboretum. Blossom-End Rot (linked in text)
12. Digger magazine. Colored pots: USDA-ARS research by Shreckhise and Owen, November 21, 2024 (linked in text)
13. Bubl C, OSU Extension. Is it safe to grow food in regular 5-gallon buckets? Ask Extension, February 17, 2023 (linked in text)
14. University of Maryland Extension. Self-Watering Containers, updated March 4, 2024 (linked in text)
15. Higgins S. AEN-157, Wicking Containers: A Self-Watering Garden System. University of Kentucky Cooperative Extension, revised April 2024 (linked in text)
16. Geldhof B, Novák O, Van de Poel B. Leaf ontogeny modulates epinasty through shifts in hormone dynamics during waterlogging in tomato. Journal of Experimental Botany 2024;75(3):1081-1097. doi:10.1093/jxb/erad432 (linked in text)
17. The Cary Company. What Are the Dimensions of a Standard 5 Gallon Bucket? (linked in text)