How to Make a Sub-Irrigation Planter

DIY Ideas
Sub Irrigation Planter

In case you are tight on space but you still wish to grow vegetables, it's best to used SIP - sub irrigation planters, also known as self-watering containers. This is a very cheap and effective method that will save you a lot of space and allow you to grow your vegetables almost anywhere.

The best thing is that most people already have all the supplies needed to build SIP. In case you don't have them, don't worry: all these supplies are very easy to get and they are very cheap.

Sub irrigation planters allow you to grow a bunch of different vegetables and herbs in a very small space. These are self-watering containers you can make easily. They are also pretty cheap, so you won't have to spend a fortune to have these useful containers. Just look around your house for all the materials needed. In case you don't have them, look around your neighborhood. Chances are that you will find them all for free or at a very affordable price.

How These Containers Work

Before you make self-watering containers, it's important to know how they work. They are not the same as regular planting containers. With SIP, the roots are directly watered from the reservoir container below.

Regular containers, including planter containers, have to be watered from the top. It means that you pour the water on the plants and the ground. The water then has to penetrate the ground and reach to the roots. It sounds good in theory, but in practice, not all the water reaches the roots. It means that some of the water is always lost and you can never tell how much you should really water your plants.

You don't have this problem with self-watering containers. SIP are made of two containers: the main one (the planting container) and the reservoir one (with water). The outside container is the reservoir one and it's made to hold the planting container and the water.

This is a more natural way to water your plants and it brings much better results than watering from the top. It also prevents you from over-watering or under-watering your plants because you will always be able to tell how much water you truly use.

Tools and Materials Needed

To make a SIP, you will need certain tools and materials you can easily find.


  • Drill
  • A good 3 1/2" hole saw (for metal and wood)
  • A good 1 1/4" hole saw (for metal and wood)
  • 1/4" drill bit


  • Two 5 gallon containers (preferably food-grade ones). One will be used as a planter and the other one as a reservoir container for watering.
  • One half of a deli container (for wicking basket).

The good news is that you don't really have to buy the 5 gallon containers. Chances are that you can find some in your home or neighborhood. If you can't, there are many places where you can get them for a buck or less. Ask in your local deli, bakeries, restaurants, farmers markets and flower shops. Many of them will have 5 gallon containers they don't use and chances are that they will be more than happy to sell them to you for a buck or less. You may even get some of them free.

Once you establish good relationships with local stores, you may even have them call you to let you know about all the spare containers they may have. It's always a good practice to pick them up, even if you don't need them at the moment. Every gardener needs a lot of containers and they will always come in handy.

How to Make Your SIP

Making your self-watering containers is easy. Simply follow the instructions below:

  • Take the 1/4" drill bit and drill many holes in the deli container.
  • Use 3 1/2" hole saw attachment on the drill to drill a large hole in the bottom of the container. Drilling in a counter-clockwise direction is the easiest way to go.
  • Take the 1/4" drill bit again and drill holes in the bottom of the planting container. These holes are needed for drainage.
  • Place the wicking basket in the middle of the reservoir container.
  • Place the planting container in the reservoir container and carefully align the wicking basket with the hole in the middle.
  • You may notice that there is some space between the wicking basket and the planting container. You may duct tape the basket to the bottom of the container to keep it secure, but it's not necessary.
  • Take the containers and hold them up to the light. If done right, you should see through the reservoir container where the planting container is.
  • Use the 1 1/4" hole saw and drill a hole 1/4" in the reservoir container directly below the planting container. This is the hole that will be used to water your plants.

How to Use Your Container

Your SIP is now ready to be used. Simply place the panting container inside the reservoir one and fill the reservoir with water.

Make sure to fill the wicked basket container with soil and moisten it with water. After this, add more soil to fill the planting container. Make sure to moisten it. Your planter is now ready for the plants.

Add your plants about 2-3 inches from the top and surround them with more soil. For the best results, it's important to keep the soil moist.

To water a SIP, simply remove the planting container and pour the water directly into the reservoir container. Add water until it reaches the overflow hole.

Since there are holes in the planting container, the water will enter the container and reach the plants' roots without a problem.

Depending on the circumstances, such as the plant type, sunlight and temperature, you will have to water your plants once per week or once in several weeks.

Photo credit: Ms. HC

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