Can You Grow Plants in a Can? (6 Things to Remember)


Are you fed up with throwing away cans and trying to find a use for them?  Well, there just might be a way to find another life for your cans.

So, can you grow plants in a can?  You can grow plants in a can, as long as it is the proper size.  Small soup or vegetable cans are good for seed germination.  Coffee or paint cans are good for growing flowers and herbs.  Larger cans are good for growing vegetables with deeper roots.

Of course, you can’t just put soil and seeds in a can and start growing.  Depending on the can, you might need a liner, drainage holes, and the proper soil mix before you plant.

You also need to be careful about temperature fluctuations in cans.  There’s a lot to keep track of, so let’s dive into the details now.

Here we go.

Can You Grow Plants in a Can?

You can grow plants in a can, but there are several factors to consider before you do.  For example, you will need to think about:

  • Size
  • Drainage
  • Liner
  • Soil
  • Watering
  • Temperature

Let’s start with can size, since you will need to decide on this before you make any other choices.

Size

There are many different sizes of cans available, and each size has its own uses.

Remember that if you leave a plant in a can that is too small, its growth will be stunted later on.  This is because a small can does not have enough space to support a large root system for a plant.

Below is a table summarizing the best use for 3 sizes of cans. More detail on each size follows the table.

Can SizeExampleBest Use
SmallSoup canSeed Germination
MediumPaint canHerbs & flowers
LargeTrash canVegetables & deep
rooted plants

Small Cans

A small can holds very little soil.  It will not support a full grown plant.

Small cans are more likely to blow over in windy weather, even when full of wet soil.  This makes them a better choice for indoor growing than outdoor gardening.

However, you can use a small can to start one or more seeds indoors.  After seed germination, you can let the seedling grow in the can for a short time.

winter melon seeds
Use small cans to germinate seeds and grow them until transplant.

Eventually, you will need to transplant the seedling outdoors or into a larger container.

You might also be able to use a small can to grow a small amount of an herb, a small houseplant, or perhaps a small cluster of flowers.

Some examples of small cans include:

  • Soup cans (Campbell’s, Progresso, etc.)
  • Vegetable cans – consumer size (retail) cans that hold beans, peas, etc.

Medium Cans

A medium can holds a lot more soil than a small can.  In fact, it would take several small cans to fill a medium can.

A medium can is still not large enough to support most full grown plants.  For example, tomatoes and potatoes have roots that are too deep for a medium can.

However, a medium can allows you to start more seeds than a small can.  You can also leave the seedlings in the can a little bit longer before you need to transplant, due to the increased size and depth of the can.

In addition, you can grow a larger amount of herbs, a medium houseplant, or a larger cluster of flowers in a medium can.

Some examples of medium cans include:

  • Coffee cans
  • Food service cans – commercial size cans (for restaurants) that hold bulk amounts of beans, pudding, etc.
  • Paint cans – any cans that held primer, paint, sealer, etc.  If growing vegetables, be careful about chemicals.  Paint cans are not food safe like coffee or food service cans are.  You may need a liner for these cans (more on this later).
coffee can
A coffee can is a good medium size can for growing herbs or flowerrs.

Large Cans

A large can holds more soil than a medium can, and it would take several medium cans to fill a large can.

A large can is able to support some full grown plants, due to its increased width and depth.  For example, you can grow potatoes, carrots, and perhaps even determinate tomato varieties in a large can.

A large can allows you to start many seeds for germination at once.  You can then leave the seedlings to grow after you thin them.

You can grow multiple different types of herbs, multiple houseplants, or a large bunch of many different flowers in a large can.

Some examples of large cans include:

  • Metal 5 Gallon Cans
  • Metal Trash Cans

Drainage

Now you’ve decided on the size of can you want to use for growing.  It’s time to make sure that it will drain well.

Since metal is nonporous, there is no way for water to escape through the sides or bottom of a can.  Instead, you will need to make drainage holes in the bottom of the can or low on the sides of the can.

You can do this by making holes with a drill.  Be careful when using a drill, and make sure to secure the can with a vise before you start drilling.

Also, remember to drill the holes before you fill the can with soil.  Otherwise, you will have a difficult time when drilling – not to mention a mess of soil and metal shavings.

According to the North Carolina State University Extension, you should not put rocks or gravel in the bottom of the can.  Contrary to popular belief, this does not improve drainage.

In fact, it makes drainage worse, since the water will collect in the soil just above the rocks or gravel.

Liner

A can liner will serve multiple purposes if you decide to use one.

First of all, a liner will protect metal from contact with wet soil.  This prevents rust and corrosion due to contact with the combination of water and air.  Even if the can does rust or corrode, the liner will prevent it from getting into the soil.

A liner will also help to insulate a metal can from cold temperatures.  This is helpful if you leave plants in cans outside in the spring, when there is still a danger of overnight frost.

If you do opt for a liner, you can use food safe plastic (such as sandwich wrap) if you are growing vegetables.  Just remember that you will also need to make holes in the bottom of the liner to allow for drainage.

Soil

Now that you have a can with a liner and proper drainage, it’s time to find the right soil for growing.  Ordinary soil won’t do the job, since we need a special blend for growing plants in a can.

What we want to use is potting soil.  Potting soil contains a mix of peat, vermiculite, bark, and coir fiber (ground coconut hulls) to improve drainage and aeration (air in soil).

soil
Potting soil contains material that helps with drainage, such as peat, bark, and other natural fibers.

According to the University of Illinois Extension, there are some plants that like soil that drains well and does not hold moisture for too long.  For example:

  • Perennials
  • Herbs
  • Succulents

You can add perlite or sand to your soil mixture to help with drainage and water management for these plants.

Remember to leave space at the top of the can for watering.  If the can is filled to the very top, then water is more likely to spill over the top of the can and make a mess when you water your plants.

If you are tempted to use ordinary garden soil for growing plants in a can, you might want to rethink it.  There are several reasons to avoid ordinary garden soil for container planting:

  • Poor drainage – Garden soil may have too much clay, resulting in poor drainage.
  • Bugs – garden soil may contain bugs (or their eggs), which may be happy to eat the plants in their new home!
  • Diseases – diseases in your garden soil are more likely to affect seedlings that have not had a chance to establish themselves and build up their strength yet.
  • Weeds – garden soil may contain the seeds of weeds, which will grow in your cans and choke your plants unless you pull the weeds out after they grow.

Watering

You will need to keep your plants watered properly to keep them alive.  Just as forgetful gardeners can lose plants due to drought, thoughtful gardeners can lose plants by over watering.

Before adding any water to the soil, feel the soil to a depth of 3 inches with your fingers.  If it feels dry, go ahead and water.

Add water until some of it runs out of the drainage holes at bottom of the can.  It is better to water deeply and less often, since this encourages a plant to develop a strong root system.

water
Check the soil for dryness with your fingers before you add any water. You can drown plants with over watering.

Remember to put the can over a saucer large enough to hold any “overflow” from watering, unless you want a mess!

If dry soil is a problem, you can also dry double potting to help retain moisture in the soil.  Double potting means placing the can in another larger container, which is filled the rest of the way with soil.

Temperature

Remember that metal cans heat up fast on a hot day.  They will heat up even faster on a sunny day, especially if they are painted a dark color on the outside.

As metal cans conduct heat from the air and absorb energy from sunlight, they will transfer heat to the soil and plants in the can.  Your plants can overheat in no time when they are in a can outdoors.

To prevent this problem, keep your cans indoors or give them some shade on sunny days. 

Alternatives to Growing Plants in a Can

If you don’t want to grow plants in a can, there are some alternative methods you can try.

cardboard boxes
You can use cardboard boxes as containers for your gardening, instead of cans.

Conclusion

Now you know about the things to look out for if you decide to grow plants in a can.  You also have some good ideas for alternatives if you want to try something else.

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jonathon. I’m the gardening guy (not guru!) who is encouraging everyone to spend more time in the garden. I try to help solve common gardening problems so that you can get the best harvest every year!

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