What Can You Grow in a Pot This Size? A Beginner’s Container Guide
The question isn’t “what should I grow?” It’s “what will actually work in the pot I’ve got, or the one I’m about to buy?” Most beginner growing advice works backwards: it picks a crop first and mentions the container as an afterthought. That’s how people end up with a radish that’s forked and stunted, or a tomato that never fruits, because the pot was wrong from day one and nobody said so up front.
This is a container-first guide to pot size for vegetables. No yard, no raised bed, no assumption that you’ve got anything more than a windowsill, a balcony rail, or a spare corner of floor space. Match the pot you have, or the one that actually fits your space and budget, to a crop it can support, and skip the guesswork. The numbers below come straight from the pot depths in our windowsill growing guide, so if you’ve already read that one, this is the same data laid out by container size instead of by crop.
What Can You Grow in a 6-Inch Pot?
A 6-inch (15cm) pot, the most common “starter” size sold at hardware stores and supermarkets, is deep enough for radishes, loose-leaf lettuce, chives, baby spinach, and a single basil plant. It’s the minimum working depth for most compact leafy crops and quick root vegetables. Go shallower than that and roots don’t have room to develop properly; go deeper and you’re really only gaining benefit for larger, longer-season crops like tomatoes or kale.
The Full Container-Size Cheat Sheet
Sorted smallest container to largest, so you can start from what you’ve already got and see what fits.
| Crop | Minimum Pot Depth | Pot Width | Light Needed | Time to Harvest |
|---|---|---|---|---|
| Microgreens (sunflower, radish, pea shoots) | 2in (5cm), a shallow tray or takeaway container works | Any width | 4–6 hrs indirect light or low light (a grow light also works) | 7–14 days |
| Green onions / scallions | 4in (10cm) | Any narrow container | 4–6 hrs direct or bright indirect | 21 days from scraps; 60–70 days from seed |
| Radishes (Cherry Belle, French Breakfast) | 6in (15cm), depth cannot be skimped | 8in (20cm) | 6 hrs direct sun | 22–30 days |
| Loose-leaf lettuce (butterhead, oak leaf, red sails) | 6in (15cm) | 10in (25cm) | 4–6 hrs, one of the most tolerant crops here | 30–45 days, then keep cutting outer leaves |
| Chives | 6in (15cm) | 6in (15cm) | 6 hrs direct sun | 30 days from transplant; 60+ from seed |
| Baby spinach (Bloomsdale or dwarf variety) | 6in (15cm) | 8in (20cm) | 4–6 hrs direct sun | 40–50 days for baby leaves |
| Basil (sweet Genovese) | 6in (15cm) per plant | 6in (15cm) per plant | 6–8 hrs direct sun, this one genuinely needs it | 21–28 days from transplant |
| Dwarf chili peppers (Prairie Fire, Numex Twilight) | 8in (20cm) | 8in (20cm) | 8+ hrs direct sun | 70–90 days from transplant |
| Dwarf kale (Dwarf Blue Curled, Red Russian) | 10in (25cm) | 10in (25cm) | 6 hrs direct sun | 50–70 days, then keep cutting outer leaves |
| Cherry tomatoes (Tumbling Tom, Tiny Tim) | 10–12in (25–30cm) per plant | 10–12in (25–30cm) per plant | 8+ hrs direct sun, your single sunniest spot, no exceptions | 55–70 days from transplant |
One Thing to Watch For, Per Crop
- Microgreens: mould from overwatering, mist or bottom-water only.
- Green onions: change the water every 2 days at the glass stage, or the roots rot.
- Radishes: a too-shallow pot causes forked or cracked roots, this is the single most common radish failure, and it’s a container problem, not a skill problem.
- Lettuce: heat above 75°F (24°C) turns it bitter fast.
- Chives: overwatering causes silent root rot, when in doubt, wait a day before watering again.
- Spinach: warmth plus irregular watering together causes bolting.
- Basil: cold below 50°F (10°C) kills it, keep it off cold glass in winter.
- Chili peppers: low light means leaves but no flowers or fruit.
- Kale: aphids on leaf undersides, check weekly, remove by hand.
- Cherry tomatoes: inconsistent watering cracks and drops fruit. Overwatering looks different: the lower leaves yellow first, and the plant can wilt even with the soil still wet, so don’t mistake that for thirst. Check the soil before you water again.
Balcony Rail Planters: What Actually Fits
If your growing space is a balcony rail rather than floor space, the container itself sets a hard limit before you even get to the cheat sheet above. Most hook-over or clip-on rail planters run about 6–7in (15–18cm) deep, enough for lettuce, chives, spinach, radishes, and a single basil plant, all of which top out at a 6in (15cm) minimum in the table above.
What a rail planter genuinely can’t do is grow a cherry tomato, dwarf kale, or chili pepper, those need 8–12in (20–30cm) of depth, which no rail-mounted box on the market provides. If you want those crops and only have a rail, you need a freestanding pot on the balcony floor instead, not a bigger rail planter. That’s a real limit, not a workaround to push past.
Reading the Table: Small Container, Big Container, or Somewhere In Between
Three practical tiers cover almost everything in this guide:
- Under 4in (10cm) deep, a shallow tray or takeaway container. This is microgreens territory. Nearly any food-safe container with drainage works; depth matters less than surface area here.
- 6in (15cm) deep, the standard nursery pot. This single size covers six of the ten crops above: radishes, lettuce, chives, spinach, and basil. If you’re only going to own one pot size, this is the one that does the most work.
- 8–12in (20–30cm) deep, a proper container, not a windowsill pot. Chili peppers, kale, and tomatoes need this much room and this much light. These are floor-space or full-sun-windowsill crops, not rail or shallow-tray candidates.
You don’t need to buy purpose-made pots to hit these depths. A 6in (15cm) nursery pot, a large yogurt tub with holes punched in the base, or a 5-gallon bucket all measure up, what matters is the depth and the drainage, not the price tag or the branding.
Light: The Other Half of the Equation
Depth gets a plant’s roots what they need; light gets the leaves and fruit what they need, and skipping this half of the equation is why a correctly-potted plant can still fail. Use your sun-facing window, the exact compass direction that gives the most light depends on your hemisphere, so “sun-facing” is the instruction that works no matter where you live.
As a rule, the crops that need the most depth also need the most light: cherry tomatoes and chili peppers want 8 or more hours of direct sun, while microgreens, green onions, and lettuce tolerate 4–6 hours, including bright indirect light. If your sunniest spot only gets a few hours a day, build your container choices around the crops in the “4–6 hours” column rather than fighting for a tomato that won’t fruit. (Seasonal light levels shift through the year regardless of hemisphere, treat the hours above as a guide for your brightest stretch of the year, not a year-round guarantee.)
No Drilling, No Deposit Risk: Renter-Safe Containers
Every container option in this guide works without touching the property you’re renting. Hook-over rail planters clip onto an existing rail. A nursery pot or a repurposed tub sits on a windowsill or floor with a saucer underneath. Nothing here requires drilling, adhesive hooks, or permanent fixtures, and everything is portable if you move.
That’s a deliberate line, not an accident. This site doesn’t tell renters to get a yard, and it doesn’t drift toward livestock or acreage the way a lot of “beginner homesteading” content quietly does once you scroll past the introduction, no chickens, no yard, no exceptions. A pot on a rail or a windowsill is a complete, real starting point, not a placeholder for something bigger you’re supposed to want next.
Common Mistakes
- Choosing the pot after choosing the plant. Decide what will fit your actual container first, buying a cherry tomato seedling and then discovering your only pot is 6in (15cm) deep wastes a growing season.
- Skimping on depth for root crops. Radishes are the clearest example: a shallow pot doesn’t just slow them down, it physically deforms the root.
- Assuming “bigger is always better.” A shallow-rooted crop like microgreens or green onions in an oversized, deep pot holds more moisture than the roots use, which raises the risk of rot rather than helping the plant.
- Skipping drainage holes. Every container in this guide needs them, no exceptions, a saucer underneath protects the surface beneath it, which matters most in a rental.
- Expecting a rail planter to grow a tomato. The container sets the ceiling before the crop choice does. Check the depth first.
Where This Fits
This cheat sheet is the container-size companion to the windowsill growing guide and the microgreens guide, both cover a subset of what’s listed here in more depth. If lettuce is the crop you’re chasing, how to grow lettuce indoors walks through variety choice and light in full. And if your growing space is genuinely a balcony rather than a windowsill, how to start a balcony vegetable garden covers the larger-container end of this same logic. And if you’re wondering whether two herbs can share one of these pots, can herbs share a pot covers which pairings work and which don’t.
And once you’ve matched the pot to the plant, our vertical vegetable garden guide covers what to do when you run out of floor space.
For the wider argument on why none of this requires owning property, homesteading for renters makes the full case.
One pot, matched to what it can actually grow, that’s the whole method. Everything else in this guide is just the numbers to check before you buy.
