If you grow your own fruits, vegetables, and herbs, you undoubtedly have at least one or more raised beds that you use for growing your favorite varieties. While raised beds make gardening so much easier for a number of reasons, there are certain limitations to what you can and shouldn’t grow in these highly useful and convenient structures. Some plants you should avoid growing in raised garden beds at all costs include cane fruits, pumpkins, corn, mint, asparagus, and rhubarb.

One of the main reasons that the following 12 plants shouldn’t be grown in a raised garden bed is that they simply grow too expansively and will crowd out anything else you might want to grow. In fact, overcrowding could be the overlooked mistake that’s making your garden beds look bad. In addition, some of these plants have extensive, and often invasive, root systems that won’t allow any other crops to thrive. Plus, plants like blueberries need a specific type of soil that may not be conducive to growing other vegetable varieties. It’s also not ideal to grow perennial crops in raised garden beds because they need to remain in the same spot year after year. This means you won’t be able to utilize the space to grow your annual vegetables. 

Growing your own raspberries is not that difficult as long as you learn the correct pruning techniques to ensure a bumper summer crop. However, they’re quite large perennial plants and do require a strong trellis to support the sprawling canes. On top of that, these plants have a tendency to send up suckers that are more likely going to escape the confines of your raised garden bed, making it that much more difficult to control their spread. Raspberries are far better grown along a fence elsewhere in the garden, allowing you easy access for picking and pruning. 

Blackberries have the same growth habit as raspberries, which means they can take up a lot of space and are not recommended for raised garden beds. Apart from their sprawling growth and tendency to sucker, they’re also perennials, which means that they’ll send up new canes each year. This makes them unsuitable for raised beds because you won’t be able to utilize the beds for growing any other crops throughout the year. You’ll also find that removing the suckers from other areas is extremely difficult and may require multiple attempts. 

The reason corn shouldn’t be planted in a raised garden bed has to do with its tall growth habit and also the way the cobs are pollinated. If you’ve ever grown corn in your garden, you’ll know that it can grow 6 to 8 feet in height, and this will make it tower quite high above your raised bed and possibly shade out other crops. Plus, the plants are wind pollinated, which means they really need to be planted in scattered rows or blocks to ensure the pollen can easily land on the silks of the cobs. 

While it’s a real delight to grow pumpkins in the garden, the plants get far too large to fit into a raised garden bed. The huge vines like to scramble over the ground and often put down roots where they touch the soil. Each vine can easily grow to over 20 feet long, which would overwhelm a raised bed and you’ll find that the vines will escape over the edges as they continue to flourish. Essentially, this means you won’t be able to grow any other crops in the same bed until your pumpkin has finished its massive growth. 

Although blueberries grow on a shrub and are actually quite easy to grow in a large container, they should never be planted in a raised garden bed. These plants are perennial, which means they’ll grow for quite a number of years in the same location. This eliminates your ability to plant any seasonal crops in the same spot. You’ll also find that blueberries require acidic soil with a pH between 4.5 and 5.5, which is not going to be conducive to growing many types of companion plants. 

Watermelons grow on vines similar to pumpkins and need lots of space to expand, which means they’re not ideal for growing in raised beds. In fact, if you want large, juicy fruits, you really need to give these plants plenty of room to spread out. Otherwise, you’ll probably end up with teeny, tiny melons and a vine that’s just itching to escape the confines of the garden bed. Watermelon plants also have sensitive roots, so you want to avoid any kind of disturbance to their root system once they’re planted. 

You’ll find that squash plants just grow far too large to be grown successfully in a raised garden bed. Over time, they’ll take over the entire space and crowd out anything else you may have planted. Whether you’re growing the vining types or those that grow as a bush, like zucchini, they all need plenty of space to spread out. Their enormous leaves will shade the soil, which means nothing else will thrive near them. Unless you can dedicate an entire bed to your squash plants, these are better grown elsewhere in the garden.

While mint makes a lovely companion plant for many of the vegetables you might like to grow, one of the downsides to growing mint that you should be aware of is its aggressive spreading growth. This means it should never be planted into a raised garden bed. It will take over completely and cover every other plant that gets in its way. Ideally, mint should be grown in its own container which will contain the roots and stop the plant from spreading. You can then place this next to your raised bed to still enjoy all its benefits. 

Lemon balm is related to mint and has the same aggressive growth abilities. Therefore, you want to avoid planting it in your raised garden bed, because it will inevitably take over and crowd out all your other vegetables. Like mint, lemon balm is best grown in its own pot to help contain is aggressive spread while still enjoying its benefits and a bountiful harvest. In fact, this lemon-scented herb will thrive next to zucchini in the garden, and when in flower, it will attract those necessary pollinators that your zucchini plant needs. 

Although it’s feasible to grow potatoes in a raised garden bed, you would have to dedicate an entire bed to this crop. You see, potatoes are grown differently than other crops and need constant hilling of soil around the plants if you want a large harvest. This effectively limits anything else that can be grown around them because you don’t want to accidentally cover your other crops with additional soil. The other problem with potatoes is, no matter how thorough you are at harvest time, you’ll undoubtedly miss some tiny tubers and these will regrow into new plants. 

Growing asparagus in your garden can be immensely rewarding because it’s a perennial and will provide you with an ever-increasing supply of tender spears year after year. However, this plant does have a deep root system which raised beds may not be able to accommodate. Both the crown and the root system can spread to a diameter of 5 to 6 feet, with the roots going down around 10 to 15 feet. Plus, an asparagus plant can grow for around 15 years, so it needs a spot where it can happily thrive undisturbed. 

Rhubarb is another perennial that demands an enormous amount of space. A single plant needs a space that’s at least 3 feet in diameter, which means it would require an entire raised garden bed dedicated to its growth for at least 15 years or more. It’s much better to grow rhubarb elsewhere in your garden, so that it can continue to grow without disturbance.