For me, the greenhouse has always been the hallmark of a devoted gardener. After all, they are designed to squeeze more growing time out of the year. However, greenhouses often take up a lot of valuable gardening space (and money! But what if I told you you could build a greenhouse on your raised bed? With a raised bed greenhouse, you'll get a longer growing season and a happier crop while saving space!
Raised bed greenhouses are a great DIY project, but they require some planning. Before building, you must assess what your garden needs (think about location, materials, timing, etc.). You'll then choose from one of the many designs that work best with your particular raised garden bed. At first this may seem daunting, but we'll cover everything you need to know!
Why Choose a Raised Bed Greenhouse?
Before we get into the technical details, let's make some raised bed greenhouses 101. Garden bed greenhouses differ from traditional greenhouses in that they are not regulated by temperature and humidity. Instead of artificial heating, these structures heat the soil by absorbing heat from sunlight. So while the vegetables and flowers inside will be a bit more roasted, you won't be able to actually control the temperature or heat the soil to suit the plants outside the gardening zone. Another key difference is that greenhouses for raised beds are smaller and generally more portable.
Marginal heat differentials come in handy at the beginning and end of the growing season, such as when winter starts to settle. Often, your garden plants will sense the drop in temperature and end their life cycle (or go dormant underground). But when we raise the temperature and extend the growing season, we can take weeks or even months out of our gardens. This is especially true for late-harvest products such as winter squash.
In addition to harvesting later in the season, you can also plant sooner (this makes gardening almost year-round! It depends on the plant, but many can be planted in the soil in early spring for up to 1-2 months. Frost-tolerant plants such as Spinach is a great candidate for planting in raised beds in late winter. To determine how early you can start gardening, use a thermometer to observe the temperature in your raised garden greenhouse and compare it to the planting temperature on the seed pack.
Raised bed greenhouses are handy for protecting plants from pests and harsh weather conditions during spring and summer. They're also great for gently hardening new plants (or just baby your favorite herbs and vegetables! In winter weather, when the ground soil is too cold to grow, a garden bed greenhouse will help protect temperature-sensitive raised beds in a raised bed) roots of dormant plants.
Raised Bed Greenhouse vs. Raised Bed Cover
If you have a raised garden bed, chances are you've dabbled with raised bedspreads. Mulches are great in gardening, but they don't always provide raised garden beds and soil like a greenhouse. The key difference is in the materials. Raised bedspreads are usually made of fabric material with aeration holes, mesh or even chicken wire to keep pests out, but not to retain heat. Mulches with a solid mulch, such as thick plastic or glass, are technically greenhouses because they keep the soil warm and growable. So, basically, a raised bed greenhouse is a very effective raised bedspread.
Things to Consider
A greenhouse is a great addition to raised bed gardening, but it's not a panacea for garden beds. It comes with some limitations and small obstacles that you should be aware of.
The biggest limitation is that raised bed greenhouses won't grow any of the plants you want. It will only help the soil reach a certain temperature and humidity, it all depends on where you live. Plants that don't grow on raised beds in the ground or climate zone won't do better in a raised bed greenhouse (sorry, but dragon fruit doesn't grow outdoors in Idaho winters). For this, you need a temperature and humidity controlled greenhouse system.
Another important factor is that the raised bed greenhouse is completely solid, which does not allow much airflow. Even if it's not airtight, you'll need to get some real airflow through the system to prevent bacterial growth. You'll also want to open the greenhouse during heat waves to make sure the soil temperature and roots don't get too hot (depending on the weather you live in).
Finally, any greenhouse system creates a barrier between pollinators and plants. If you want to grow fruit, you must open the raised bed greenhouse when the plants are blooming.
Types of Raised Bed Greenhouses
There are many variations in the construction of raised bed greenhouses, but most are one of two basic structures: hoop house or cold frame. These categories have their pros and cons, but both are excellent choices for near-year-round gardening. Plus, there's a lot of room for creativity!
basketball home
We actually have an entire article on raised bed hoop houses, but here's a quick rundown. Hoop houses are usually a cheaper temporary option. They have round frames (hoops) that support some type of solid lid - usually thick plastic. The Hoop House is a quick DIY project that is easy to put on and take off. Therefore, they are usually only placed when needed. Because they are so temporary, hoop houses rarely have hinges or easily accessible vents.
The hoop house structure should be made of something that is easy to bend into shape. Thin PVC pipe is the most popular choice due to its flexibility and ease of use. You can also use thick wire, hoop house kits, and even hula hoops! The lid also needs to be flexible, as well as clear and durable.
There are several ways to assemble a hoop house on a raised bed. The easiest way to do this is to insert the end of the hoop into the soil and then cover it. If you have a wooden raised bed, you can nail the hoops to the outside of the bed. Or, for a more permanent solution, you can assemble hoop houses inside raised beds before filling them with soil (like in the plan we provide here).
cold frame
Cold frames are fancier raised bed conservatories that require some woodworking skills (or fat wallets). They attach to raised beds, usually on hinges, making them a permanent part of the garden. The cold frame is used year-round and opens easily as needed. Plus, they're often a prettier alternative to a neat box design.
Cold frames usually have wooden frames lined with high-quality plastic or glass. Many are just repurposed windows for home improvement. You can easily buy a cold frame online or just build one of these 26 free cold frame plans!
other options
Of course, you don't have to follow a pre-made raised bed greenhouse plan. This is your garden, so feel free to get creative! You can combine ideas to create your own unique raised bed greenhouse. Alternatively, you can repurpose something from a thrift store, such as a clear storage container or an empty aquarium.
Some gardeners will turn things over completely and build raised beds within existing large greenhouses. This is an excellent option that saves a lot of space and provides easy access to vegetable plants. Raised bed kits like a loft bed will be easiest to place in a greenhouse, not to mention more even.
