Garden
When to Plant
What You Cannot Grow in a 5-Gallon Bucket — It Is Not the Depth
A five-gallon bucket is out for every fruit tree, every fruiting shrub and every perennial that lives on its roots through winter. Maryland Extension puts a dwarf fruit tree at 25-30 gallons of potting mix and a shrub at 25 — five to six buckets in one container, not five buckets in a row. What rules those out is not depth. A bucket stands about fourteen inches tall, which sits inside the 12-to-16-inch depth their deepest class asks for.
It was never the depth
The line you have read a hundred times is that a bucket is too shallow. Check it against a source and it falls over.
Maryland Extension sorts container plants into three sizes. Small wants a depth of 4 to 6 inches, medium 8 to 12, and their largest class — tomatoes, peppers, eggplant, cucumbers, winter squash — wants 12-16 inches. A standard five-gallon bucket stands about fourteen inches tall. That lands inside the deepest band they publish — not at the top of it, but inside it.
So if a bucket fails you, it is not because the roots ran out of downward room. Something else went wrong, and it is worth knowing which, because the two failures have different fixes.
Two limits that get treated as one
Root volume. How much soil the plant needs to draw water and food from. Maryland's rule is plain — match container size to plant size, both the top growth and root system. Don't squeeze large plants into small containers. A bigger container fixes this completely.
The plant itself. How big the thing gets above ground, whether a twelve-inch base can hold it upright, and whether you can still lift it. No container fixes this. A bigger one makes it worse, because now it weighs more.
Almost every list of what-not-to-grow mixes these together, which is why a sprawling squash and an apple tree end up in the same paragraph. They are refused for opposite reasons and only one of them is genuinely out.
The trees, in feet rather than gallons
How wide these grow, from our own sourced records. A five-gallon bucket is about one foot across.
| Tree | Grows this wide | Buckets across |
|---|---|---|
| Mulberry | 30–50 ft | Thirty to fifty |
| Apricot | 20–40 ft | Twenty to forty |
| Persimmon | 15–35 ft | Fifteen to thirty-five |
| Pear (European) | 16–35 ft | Sixteen to thirty-five |
| Grapefruit | 15–30 ft | Fifteen to thirty |
| Fig | 10–30 ft | Ten to thirty |
| Apple | 8–30 ft | Eight to thirty |
| Cherry | 8–30 ft | Eight to thirty |
| Peach | 12–25 ft | Twelve to twenty-five |
| Plum | 10–20 ft | Ten to twenty |
What to do about a tree instead
Those are the trees at full size, and the answer is not that fruit trees cannot be grown in containers. It is that the container is a different object.
Maryland gives the number: a dwarf fruit tree wants 25-30 gallons of potting mix, and a shrub 25. That is five to six buckets' worth in one container, which is a half barrel or a stock tank, not five buckets standing in a row. Roots do not span containers.
Rootstock is what makes it possible, and it is not the variety. Our sourced spacing for apple is 6 to 8 feet between dwarf trees against 20 to 25 between standards — the same fruit, planted three times closer, because it grows a fraction of the size. We hold that dwarf figure for apple and not for most of the others, so on the rest take the nursery label's word rather than ours.
And size is only the second question for fruit anyway. The first is whether one plant can fruit alone, because seven of the fruit crops we hold cannot — a container holds one plant, and that decides more than any pot size does. Which fruit grows in a container starts there.
The sprawlers are a different no, and a softer one
Chayote runs to 50 feet. Winter squash and pumpkins reach 25. Bottle gourd 16, sweet potatoes 15, watermelon 10.
Read those the way you read the tree table and you would ban all of them. That would be wrong, and it is the mistake this page exists to stop. A vine sprawls from roots that stay in one place. The plant is fifty feet long and its root ball is not — it can sit in a container at the edge of a patio and run along the ground from there.
So for the sprawlers the question goes back to volume, where the answer is smaller than you would guess and still bigger than a bucket. Maryland puts summer squash at 10 gallons and winter squash at 8 to 10. Two buckets' worth, not six.
Which makes them the honest edge case of this cluster: a bucket will not do it, and the next size up will.
Weight, and the thing nobody mentions until it happens
Maryland is blunt about this and almost nobody repeats it. Tall plants in relatively small, lightweight containers can be blown over or become top-heavy and topple unless well-anchored.
A bucket is twelve inches across holding a plant that may be six feet tall. That is a lever with a small base, and one August storm settles it. Staking helps and it does not turn a bucket into a wide container.
The other half is the opposite problem. Maryland notes that a 20-inch container of moist mix and plants can weigh 100 pounds — so the half barrel that fixes your tree is a thing you will site once and never move again. Decide where it lives before you fill it.
One more that is specific to rescued buckets: dark containers raise the temperature of the mix and can injure tender roots. A pale bucket is a better bucket, and that is the only time on this page the object itself is the variable.
Where our own numbers stop
We hold a container size for 143 crops, and 26 of them need more than a bucket. Four of those 26 carry a citation. The other 22 are our estimate.
That is why this page argues from how wide a plant grows rather than from how many gallons it wants. Mature spread is sourced on 136 of the 148 crops that carry it — 91% — and every tree in the table above is one of them, several with two independent sources. The gallon figures for apple, cherry, fig and the rest are not, so they are not what the argument rests on.
You can check any of it in the free plant database: every value says whether it carries a source or is filled from ordinary horticulture, one at a time. We would rather tell you which of our numbers to lean on than have you find out.
For the other direction — everything a bucket is right for — see what to grow in a five-gallon bucket, and potatoes in a bucket for the one crop where somebody publishes a per-plant figure.
Questions about what will not fit
Are 5 gallon buckets too shallow for vegetables?
No, and this is the most repeated wrong thing about them. Maryland Extension's largest container class — tomatoes, peppers, eggplant, cucumbers, winter squash — asks for a depth of 12 to 16 inches, and a standard five-gallon bucket stands about fourteen — inside that band, though not at the top of it. Where a bucket falls short it is on volume, not depth, and those need different fixes.
Can you grow a fruit tree in a 5 gallon bucket?
No. Maryland Extension puts a dwarf fruit tree at 25 to 30 gallons of potting mix and a shrub at 25 — five to six buckets' worth in one container, which means a half barrel or stock tank rather than several buckets side by side, because roots do not span containers. It is also a stability question: a twelve-inch base under a six-foot tree topples, and Maryland names top-heavy containers blowing over as a real failure.
Can I grow squash or pumpkins in a bucket?
Not in one bucket, but closer than the tree answer. A vine sprawls from roots that stay put, so a fifty-foot chayote does not need a fifty-foot container — it needs somewhere to run. The limit is soil volume: Maryland lists summer squash at 10 gallons and winter squash at 8 to 10, which is two buckets' worth in a single container. Give the vine the ground beside it and the container itself can be modest.
What about perennials like asparagus or rhubarb?
Our records put both well above a bucket, but be aware those particular figures are our estimate rather than a cited source — 22 of the 26 crops we list above bucket size are unsourced, and these two are among them. What is sourced is their size: asparagus spreads 1.5 to 3 feet and rhubarb 3 to 4. The deeper issue is that both live for years, so the container has to carry them through winters, not one season.
Would two buckets work instead of one big container?
Only if you are growing two plants. A root system cannot cross from one bucket to another, so two five-gallon buckets are two five-gallon containers and never one ten-gallon one. Where a crop needs ten gallons, it needs ten gallons in a single container — joining two buckets physically, or buying one bigger thing.
Does a black bucket matter?
A little, and it is worth knowing since most rescued buckets are whatever color the business threw out. Maryland notes that dark container colors raise the temperature of the potting mix and can injure tender roots, which stops the root system developing fully. A pale bucket runs cooler. It will not rescue a crop that needed three times the volume, but on a south-facing patio in July it is a free improvement.
Sources
Every planting date, depth, and temperature on this page traces to these university extension guides. Where they differ, the ranges above hold the whole spread.
- University of Maryland Extension, Home & Garden Information Center — Types of Containers for Growing Vegetables
- University of Maryland Extension, Home & Garden Information Center — Growing Vegetables in Containers and Salad Tables
- NC State Extension — Extension Gardener Plant Toolbox
Three pages into this cluster it would be easy to leave you thinking a bucket does more than it does. It does a lot. It does not do trees, it does not do shrubs, and it does not hold up anything tall enough to catch a wind.
The useful version is that a bucket fails on volume and on balance, never on depth — so when a crop is out, check which of the two ruled it out. One is fixed by a bigger container and the other is not fixed at all.