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A planter box can be a great option for growing your own vegetables. But how big a planter do you need?

You need a planter box that is deep and wide enough for the vegetable roots to get sufficient growing space. A planter box that is 6-8 inches in size works for leafy vegetables. Root vegetables need the planter to be 8-14 inches in size. Fruiting vegetables grow in a planter 12-16 inches in size.

You’ll need to pick a planter box depending on the vegetables you want to grow in it. I’ll give you a detailed list of the different vegetables you can grow. And the average size of the planter box you would need.

Let’s get started.

Why you need a planter box with the right size?

Vegetable plants need the right amount of nutrients and moisture to grow well and give a good harvest. The plant’s roots need sufficient space in the planter box so they can spread in search of these essential components.

Some vegetable plants would need a larger planter box than others. That’s why you need to pick one with the right size. So the plants can get the required growing space, but you don’t waste soil and resources with an oversized planter box

Why you should avoid a planter box that is oversized?

If you pick a planter box for the vegetables that is too big, you’ll end up needing a lot of potting soil. This means you spend more money on the soil than needed.

If the planter box contains a lot of potting soil, the roots can’t absorb all the moisture and it may remain at the bottom longer. This increases the risk of overwatering and causing fungal issues such as root rot.

If the planter box contains more depth than required, the potting soil may shift underneath and cause the plants to topple over.

What size planter box for leafy vegetables?

Many leafy vegetables are small and can grow well in a small size planter box. These include vegetables like lettuce, spinach, and kale.

A planter box that is 6 to 12 inches in depth and width should grow most such leafy vegetables. You could even grow several together depending on the plant and variety.

Here is a list of some leafy vegetables you can grow in your planter box and the size you would need

PlantPlanter Box Depth (inches)Planter Box Width (inches)
Bok Choy812
Mustard Greens68
Swiss Chard8 12

What size planter box for herbs?

There are many herbs that are small and you can grow in a small planter box. You don’t need as much of herbs and could grow several together as well. Just pick herbs that won’t compete for resources.

You can use a planter box that is 6-12 inches deep and wide for growing many types of herbs, such as cilantro, mint, and sage.

You can find a list of herbs to grow in a planter box and the size that you would need to grow them.

PlantPlanter Box Depth (inches)Planter Box Width (inches)
Marjoram6 6

 What size planter box for root vegetables?

Many root vegetables can grow deep roots depending on the vegetable and the variety. So you need a planter box that is at least 6-24 inches deep. I’ve also included plants like potatoes and garlic on this list.

If the planter box is large enough, you should be able to grow several root vegetables. Either of the same type or different vegetables.

Leave sufficient spacing between the vegetables. You want at least 4-6 inch spacing between them. But check the seed packets and online information for each root vegetable you grow.

Here’s a list of some root vegetables and the planter box size you would need.

PlantPlanter Box Depth (inches)Planter Box Width (inches)
Sweet Potatoes1818

What size planter box for fruiting vegetables?

Fruiting vegetables are plants such as tomatoes, peppers, cucumbers, and eggplants. Most varieties of these plants grow large and have deep roots.

You need a large planter box with the required width and depth that ranges from 8 to 12 inches at least. I’ve also added vegetables like asparagus and Brussels sprouts to this list.

I would not suggest growing different fruiting vegetables together as they may compete for nutrients and resources. So one may overpower the other and not allow it to grow well.

Here is a list of some fruiting vegetables you can grow and the planter box size they need.

PlantPlanter Box Depth (inches)Planter Box Width (inches)
Brussels Sprouts1212

Further Reading

Choosing a planter box of the right size is just one of the many things you need to understand for a successful vegetable container garden. You can find all the basics noted in the post below,

Here are some of my favorite container gardening tools

Thank you for reading this post. I hope it helps you with your gardening needs. I’ve listed some tools below that can help you with container gardening. These are affiliate links so I’ll earn a commission if you use them.

Gardening Gloves – I find the Pine Tree Tools Bamboo Gardening Gloves really good for both men and women. It’s made from bamboo so helps absorb perspiration. They are also comfortable and fit very well.

Containers – You know picking the right container is crucial for your container gardening. I’ve written a detailed post on the best containers you can choose from. If you’re happy with a plastic container, you can check out the Bloem Saturn Planter.

Watering Can – This is a must-have tool when you’re growing plants in pots or grow bags. It helps to water the potting soil without splashing on the foliage. The Kensington Watering Can is stylish, strong, and can provide precision when watering potted plants.

TrowelGarden Guru Trowel is my favorite because it’s durable and comfortable to use. My gardening friends really love having a trowel because they use it for digging soil, mixing fertilizer, moving seeds, leveling out the soil, mixing compost or mulch, and also dividing tubers

Bypass Pruner – I really like the Corona Bypass Pruner because it’s durable and gives a clean cut that helps plants recover faster. If you’re looking for something cheap, get the Fiskars Bypass Pruner that is really good as well.

To see an extensive list of the best container gardening tools gardeners recommend, check out this resource that I made for you.