We have discussed about the size problem of a metal raised garden bed in the last blog post (What Is The Right Size of Your Metal Raised Garden Beds?) Among the three factors height seems to be the most complicated one, which is worth dwelling on in details here.
Generally speaking, the height of a metal raised garden bed should be considered based on multiple factors such as plant needs, the physical condition and ease of use of the gardener, planting purposes, and budget. When selecting the height of the bed, it is necessary to comprehensively weigh the relationship between various factors in order to find the most suitable height. At the same time, it should be noted that the height is also associated with drainage and pest control.
The needs of planting is the first consideration that determines the height of a metal garden bed. If you are growing vegetables, the height of the bed should be between 12 to 20 inches. This height allows sufficient space for the root system of vegetables to develop, and also makes it easier for you to manage the vegetables on the bed. And 18 to 24 inches for beans, beets, cantaloupe, carrots, cucumber, eggplant, kale, peas, peppers, squash, turnips, and potatoes, while 24 to 36 inches (61-91 cm) for deep rooted vegetables such as artichoke, asparagus, okra, parsnips, pumpkin, rhubarb, sweet potatoes, tomatoes, and watermelon. If you are planting flowers, the height of the bed can be preferably between 20 to 32 inches. This can make the roots of flowers healthier and also allow you to better appreciate the beauty of flowers.
Physical Condition & Convenience of Use
If you are relatively healthy, a bed with a height of around 20 inches will be more suitable for you. This height can not only meet the growth needs of vegetables and flowers, but also make it easier for you to manage the plants on the bed. If your physical condition is not good, or if your metal garden bed is relatively large, a bed with a height of around 32 inches may be more suitable for you. This height allows you to easily manage the plants on the bed without bending down, reducing the burden on your body.
You can grow just about anything you want in a two-foot-tall raised garden bed. Few plants really need two feet of depth for their roots, so the extra height is mostly just for the ease and convenience of the gardener. The closer a bed is to two feet, the easier it is to tend and harvest from your plants. You bend over from the waist and are at the plant’s level. Garden work should be an enjoyable part of your daily routine, not a chore that hurts your knees and back.
Planting Purpose & Budget
If your planting purpose is mainly for your own daily needs, a bed with a height between 12 and 20 inches is sufficient. If you want to create a beautiful garden with sufficient budget, a bed with a height between 20 and 32 inches will be more suitable for you. Of course, if you have sufficient budget, you can also choose to customize metal raised garden beds to satisfy your planting and aesthetic needs.
Metal raised garden beds drain readily and warm up earlier in spring. This means you can set out transplants sooner and extend your growing season. They provide good drainage for the soil within the bed. The most popular height for raised beds is 11 inches. This height provides sufficient drainage for most crops. For best results, there should be another 12 inches or more of good soil below the bed. This gives your plants at least 18 – 20 inches of soil. (The soil in raised beds is usually a few inches below the rim of the bed. This is because soil compresses after several waterings. Having the soil level down a few inches is useful because you will likely want to add a few inches of mulch.)
Another thing to consider is whether the height of your raised garden beds can help prevent pests. Carrot flies rarely fly above 20 inches, so higher beds can help to protect your carrot crop. A height of more than 2 feet is said to help deter rabbits, and can also help prevent damage from dogs while 1-foot tall raised beds are tall enough to help guide ducks through your garden rather than over your garden. From natural experience raised garden beds above 1 foot in height are enough of a barrier to put off ducks jumping up and onto beds most of the time. Instead, they are happier going in between the paths and around the garden boundaries looking for slugs rather than attempting to hop on and off raised garden beds.
The higher the bed is, the more imported soil will be required. This will add to the cost and labor involved in the garden project. A few other tips to keep in mind:
- Most garden crops need at least 10 inches of soil to thrive. If the raised garden bed height is lower than this, till the existing soil below the raised bed.
- If the raised bed is on top of a hard surface, the minimum recommended height of 10 inches may not be deep enough for some crops, like potatoes.
- Young children need beds closer to the ground.
- For wheelchair access, beds should be 24 inches tall.
- A bed that is 36 inches off the ground helps avoid excessive bending over.
- Consider having a mix of bed heights to accommodate different gardeners.