Gardening on the balcony and terrace has been very trendy for several years. Despite a lack of space, more and more people do not want to do without home-grown vegetables and fruits and are looking for easy-to-implement ideas for space-saving and easy-care raised beds. Today we are going to show you a creative and practical DIY raised bed for balconies and patios that enables urban gardening fans to grow many useful plants in the smallest of spaces.
How does this DIY raised bed work?
The idea of a vertical garden may not be new, but this raised bed takes the concept to a whole new level and perfects it. The secret behind it is called: compost worms! A pipe is mounted in the middle of the barrel, which serves as a composter for food waste. The worms turn leftover food into an excellent fertilizer (humus), which is the best organic fertilizer plants can get. The pipe is provided with enough holes all around so that the worms can crawl into the earth and thus fertilize the plants. They allow the soil to remain fertile for a long time and prevent the need for frequent soil replacement.
In addition, during irrigation, water penetrates the pipe and washes out the waste products. The water flows into a vessel under the barrel and is reused for watering, which brings nutrients back into the soil. So we eliminate fertilizers, save water and waste less food.
Are the compost worms really needed?
Yes, the worms are the internal engine of the raised bed that makes the plants grow insane. And anyone who is afraid of them should know that they never come out of the barrel and have no contact with the edible parts of the plants.
The compost worms (Eisenia foetida) belong to the family of earthworms. Because of their color, they are often referred to as “Red Californian worms” (English redworm, red Californian earth worm). They hate strong light and drought and cannot survive outside of the barrel. After they are put in the pipe, they are barely visible, but their benefits are immense. The humus they produce is a wonderful substance for the soil, and contains virtually everything the plant needs, including nitrogen, phosphorus, and potassium (NPK).
If, despite all of the above advantages, you have decided not to put the worms in the barrel, we recommend artificially fertilizing the raised bed with some liquid fertilizer (especially if you plan to grow edible vegetables). You can of course just plant flowers in the pockets.
How can you build this raised bed for a balcony yourself??
To build this raised bed yourself, you need a wide-necked barrel, preferably made of food-safe polyethylene, or PE for short. Recycled barrels can also be used, e.g. those from the food industry that are used to transport glucose syrup. A barrel with a capacity of 220 liters is ideal for a large vegetable garden. You can use a 60 liter barrel for a mini raised bed for balconies.
First, the slots are drawn all around the barrel. The distance between the individual levels should be about 15 centimeters. For example, 5 – 6 levels with 8 to 10 slots each are ideal.
Then holes are drilled through the start and end points and then the slots are cut with a jigsaw. The plastic is heated with heat so that these can be expanded and shaped. At this step, it is better to work in pairs. While one is holding the hot air blower, the other can insert the wooden wedges (or another suitable object). These have to stay in the hole until the plastic has cooled down.
After all the pockets have been formed, you can continue with the inner tube for the kitchen waste. For a 200 liter drum you need a pipe with a diameter of about 190 mm and a length of about 1.5 meters. The pipe must not be too small so that there is enough space for the compost. Holes with a diameter of at least 20 mm are then drilled all around this pipe.
Another hole is cut out at the bottom of the barrel in the middle, with the same diameter as the inner tube. So that the pipe does not slip through the hole in the bottom of the barrel, it is sealed around it with silicone or hot glue. Finally, the open tube is closed with a cap. To drain the barrel, a few drainage holes are drilled all around at the deepest points.
Does the barrel always have to stand on stilts?
If the keg is placed on the ground without feet, it may be unstable due to the pipe cap. It is therefore advisable to place the raised bed on stilts or another frame with legs.
The feet serve several purposes:
1. They facilitate access to the barrel and the plants.
2. They make cleaning under the barrel easier.
3. They allow the collection of the runoff water, which is basically liquid humus. This worm leach is one of the best liquid fertilizers.
4. The barrel can be moved and rotated more easily if necessary.
5. This allows the cap at the bottom of the barrel to be opened so that the compost can be removed.
Where should you put the raised bed?
The correct location is very important and there are a few factors you should consider before filling your raised bed:
Location and sunlight
A place that can provide the plants with sun for at least 3 hours a day is ideal. This is the most important prerequisite for photosynthesis in plants. Tomatoes, peppers, zucchini and cucumbers, for example, need a lot more sun.
Fortunately, if your balcony is in the shade, there are some herbs and vegetables that can develop there as well. Good crops that are comfortable in the shade on the north side are spinach, cress, chives and some types of lettuce.
How is the raised bed watered??
The raised bed can generally be watered with an irrigation hose or a watering can. If you are often away from home or forget to water, you can use an automatic irrigation system. The hoses curl inside the barrel and water the plants directly to the roots with a precise drop.
Whether you use an irrigation system or not, being close to a water source will allow you to maintain your raised bed more easily.
Fill the balcony raised bed correctly
As soon as the loft bed has found its place in a well-chosen location, it can be filled.
What soil for the raised bed?
The soil in the raised bed should be light, well-drained, nutritious and water-storing. It is advisable to mix garden soil and compost soil in a ratio of 1: 1. It is important to fill the barrel with soil to the top because the substrate will lose some of its volume when it is first poured.
Isn’t the raised bed too heavy for the balcony??
For a standard balcony, the maximum load is 250 kg per square meter. When full, a raised bed in a 200 liter barrel weighs around 100 kg and a mini raised bed weighs around 35 kg, so weight is not a problem.
The PE barrels are 100 cm high and 60 cm wide. When placed on a frame, the height is approx. 135 cm. The smaller barrel is 45 cm wide and 75 cm high when placed on its feet.
Once the barrel is filled with soil, place a container under the barrel where the irrigation residue can collect. Start watering the raised bed. When the water begins to drip into the bottom of the container, you know the substrate is saturated and ready to be planted.
Plant the raised bed
Now you can put the plants in the slots. For a better chance of success, plant young seedlings rather than seeds. Think in advance which plants you want to put in your raised bed. Growing different vegetables and herbs from different species together in one raised bed has several advantages. You should also take into account the requirements of the plants and their properties. Varieties that get very large, such as kale, cherry tomatoes, peppers and eggplants, should be planted on top. Planting the raised bed is very easy and fun. You can find more inspiration in our article: Gardening on the balcony: 10 ideas for what to plant in a raised bed
Fill the compost worms into the inner tube
Put a handful of soil in the worm pipe and empty the sack with the red worms in it. This is followed by a cup of leftover food and then another handful of earth.
What should you feed the worms with??
It is advisable to feed the worms on soft foods and preferably of high nutritional value. They prefer foods with a high sugar content, such as sweet and soft fruits, banana peel, mango, pumpkin, apples, peaches, etc. (can be given whole or with seeds). You can also feed coffee grounds to compost worms. They also digest bread, rice, pasta, and other vegetables. It is advisable to avoid foods that are too spicy or fatty, such as meat, dairy products, eggs, and acidic foods such as tomatoes and citrus fruits.
The compost worms should be fed gradually:
In the first month – one cup of food a week
In the second month – two cups of food a week
In the third month – three cups of food a week
From the third month, continue with 3 cups of food a week.
The worms reach a length of approx. 5 cm. Each worm eats around half its body weight per day and digests a kilogram of waste every year! They multiply every 40 days under ideal conditions, but do not worry: there will be no population explosion because they adapt their number to the existing conditions: available space, amount of food, etc..
Water the raised bed how often?
After planting, when the seedlings are still young, it is recommended to water each individual pocket. After about two weeks, when the roots have established themselves, the raised bed only needs to be watered from above. Check the soil moisture with your finger and water when the soil is dry.
Use the excess water that accumulates in the vessel under the barrel for watering. It is still called worm tea. As a result, the decomposition products of the worms (humus in a liquid state) are returned to the barrel for the benefit of the plants.