Urban Gardening the SIP Way
For those living in cities or areas where you don’t have access to land for growing your own fruits and vegetables there is still a solution for you. It’s found in the sub-irrigated planter.Just because you live in a city doesn’t mean you can’t grow your own fresh fruits and vegetables.
What the Heck is a SIP?
The sub-irrigated planter or SIP is a modern form of a raised bed with the added advantage of a self-watering irrigation system. The water is introduced from the bottom of the container, allowing the water to soak upwards to the plant through capillary action.
SIPs can be made from many different containers ranging from large to small. And once you understand the principle of how one is made you can apply that to practically any container and be well on your way to growing a fantastic garden.
Here’s a great video put together by high-school students showing you the principle of 5-gallon bucket SIP and how you can make your own:
Advantages of Sub-Irrigated Planters (SIPs)
Not only is there an 80% decrease in water usage in a plant to plant comparison than found in a typical garden but it also doubles the production output of a garden and on top of that it is weed free! Best of all this system allows city dwellers to essentially bring their own land with them and place it on their balconies, patios or a city roof.
This type of design allows for a bottom up watering approach rather than a top down approach that is typical in potted plants or plants growing in a standard garden. Since the water is pulled up from the bottom, as long as the water reservoir remains full the plants will draw the water as needed. There is no risk of over- or under-watering the plants.
How to Make Your Own
What You’ll Need
- 2 five gallon food-grade buckets that can stack inside one another
- 1” plastic pipe or tubing (pvc pipe works fine) about 3” longer than the height of one of the buckets
- smaller plastic container (a plastic cup or used hummus container works great)
- power drill with ¼ inch drill bit
- plastic bag large enough to cover the opening of one of your buckets
- snips or hacksaw to cut the pvc pipe
Step 1: Prepare the Buckets
Step 2: Drill your Holes
Step 3: Prepare the Fill Tube
|Drill or cut a hole in the bottom of the bucket that corresponds to the diameter of your watering pipe or tubing. Cut the bottom of your tubing at a 45-degree angle to prevent the tube from clogging in your bucket.|
Step 4: Cut Slits in your Small Container
|With your box cutter slice 4 vertical slits in the sides of the smaller plastic container making the slices evenly spaced around the perimeter of the cup. Do not cut through the bottom or lip of your cup.|
Step 5: Stack the Buckets Together and Drill the Overflow Holes
Step 6: Add your Potting Mix and Plant your Seedlings
Step 7: Add Fertilizer
Step 8: Suggestions on Watering
When watering you’ll want to fill the reservoir until the water comes out of the overflow holes. As mentioned before this self-watering system makes it impossible to over-water your plant. Every few days take a look at your reservoir and fill as necessary. During the growing season there may be times when you need to water every day so be sure to pay close attention.
A Word on Soil
It’s important that you do not use standard garden soil in the SIPs. Why? Well in order for SIPs to function correctly the water must be wicked from the bottom to where the roots of the plant can soak up the moisture. Ordinary soil does not provide the capillary action (wicking action) needed to move the moisture upward. You’ll need to purchase potting soil (with the main ingredient being spagham peat and/or coir). Here are some homemade recipes provided by Global Buckets:
Recipe #1: Sphagnum Peat
70% Sphagnum Peat
Recipe #2: Sphagnum Peat and Coir
35% Sphagnum Peat
If you prefer not to make your own, there is a commercial variant of a SIP called an Earthbox which can be purchased at the Earthbox.com site for $50 per box (a homemade one is much cheaper).
Also, here is :
- Global Buckets: A great site which teaches you how to make an automated watering system as well as fertilizer and soil recipes
- Green Roof Growers: A blog about three people’s experiences growing heirloom vegetables on the Chicago rooftops using SIPs.