How Deep Does A Planter Need To Be For Carrots?

Carrots can be grown quite successfully in a planter. Choosing the right planter, however, is important to accommodate the carrot’s long taproot. How deep does a planter need to be to grow carrots? Let’s find out.

On average, most carrots need a planter that is 30cm (12inches) deep. However, you can always choose a short, or even a cylindrical, that do not require very much depth at all.

Whether you plan on buying or building a planter, lets take a look at what your carrots need for container growing.

The Best Soil Depth For Carrots

All plants need adequate root space to properly grow and thrive. This is particularly true for carrots since the root is the part that you eat and it can reach deep underground. Most carrots require at least 30cm (12inches) of soil to stretch out their roots.

You might think that your carrot is only supposed to grow 15cm (6inches), so why do I need 30cm of soil? Growing off the bottom of the carrot is usually a long think root that looks like coarse hair. This is the tip of the taproot and is important for the plant to reach nutrients deep in the soil. If the container is too shallow, the root will bump into the bottom of the planter interfere with the carrot’s growth.

Unfortunately, it is difficult to buy a planter that is so deep. There are some available, but most planters are designed for flowers or herbs, that have a much shallower root ball. This might be the time for a DIY construction project. If you are building your own planter, it is better to err on the side of caution and make the planter as deep as possible. You don’t want to go through all that work and find it was all for naught. Consider making the planter closer to 40cm (16inches) deep if possible. Remember, the bigger you make your planter, the heavier it will be so put it in position before you fill it will soil.

The 5-Gallon Bucket

A good planter option for carrots is the 5-gallon bucket. It provides adequate depth and is very portable.

Signs That The Soil Is Too Shallow

If a carrot root outgrows the soil and reaches the bottom of the planter, its growth will be stunted. With carrots, this is, unfortunately, most often seen at harvest time, when you pull up a stunted, twisted, or deformed carrot. While the carrot will still be edible, a stunted carrot will never be as healthy nor as sweet as a carrot that was able to “stretch its legs.”

When a carrot does not have enough soil depth to grow it is also more likely to be woody, and produce hairy roots. Since the taproot is unable to properly grow, it has to compensate by sacrificing quality and by sending out extra root hairs to absorb the nutrients it requires.

There are some signs above ground that can also indicate that your carrots do not have enough soil depth. Cramped roots will often lead to chlorosis, which is a yellowing of the leaves due to insufficient nutrient uptake. Too shallow soil can also affect a plant’s ability to flower, which is detrimental if you are growing your carrots for seed production.

Matching The Planter To The Variety

Carrots have been bred to have a certain length to meet industry standards. In the home garden, however, there are many different carrot options you can grow. Most carrot varieties are around 15cm to 20cm (6-8inches) and these will grow well in 30cm (12inches) of soil as we discussed. However, some grow much longer than that and are unfortunately not suitable for container growing.

On the flip side, some carrot varieties are very short, and are ideal for growing in a planter. Cylindrical carrots, such as this one, are ideal for growing in planters, and would only require 15cm (6inches) or so of soil depth. Other carrot varieties are meant to be harvested small and would also do well in a shallow soil.

Self-sufficient gardening is about growing your own food, but it doesn’t say anything about where you can grow it. Growing carrots in containers is great way maximize space. You can have a delicious summer snack, or a bountiful fall harvest even if you don’t have any ground to plant your seeds.

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About the Author Harry Thompson

Involved in home renovations throughout his life, Harry is an expert in everything to do with home and garden DIY. In his spare time, he enjoys cooking and tending to his garden.