You could spend hours just sitting and watching these Jurassic-looking, acrobatic flyers zoom from here to there. Some of the oldest known insects, dragonflies provide a hugely beneficial component to your garden. They can eat hundreds of mosquitoes each day. Dragonfly larvae eat mosquito larvae in the water and dragonfly adults eat flying mosquitoes. They will also eat biting gnats and other pesky insects.
Adding a pond to your backyard can be very beneficial to dragonfly populations. They help increase local species diversity, provide refuges for common and rare species, provide "bridges" between dragonfly habitat and also create a wonderful outdoor educational opportunity.
The key to attracting dragonflies to your backyard is a water source. Dragonflies use water throughout their life cycle. Dragonfly larvae (nymphs) can spend months or even years living in the water before emerging as adults. So, adding a pond or other water feature will be essential in attracting dragonflies.
First, it's necessary to live within a few miles of some water source - a pond, river, stream, lake, etc. This is probable for most people. Try to avoid overhanging trees, as they may provide too much shade and decomposing leaves can foul the water. If it's unavoidable, make sure no more than one-third of the pond has overhanging trees. Even if not directly overhanging, you don't want shade over the whole pond in general, as it can interfere with plant productivity and deter sun-loving dragonflies. Ideally, the pond will get 5-6 hours of direct sunlight each day. However, shade on the west side of a pond can create good shade during the hottest part of the day.
Avoid areas that get a lot of runoff, as this may contain pesticides, fertilizer and other chemicals that will harm nymphs.
You should contact your local municipality to check on ordinances that dictate depth, fencing, etc. Also, be sure you are not digging near any underground utility wires.
In order to support dragonflies, the pond should provide various water depths and should have parts that won't freeze in the winter. For smaller ponds, a depth of at least 2.5 feet should suffice and 4 feet for larger ponds (depending on your climate). Ideally, the pond should be at least 43 square feet, though smaller ponds are also possible. If your soil is high in clay content, you may not need a liner as long as you compact the soil with pounding. If you do not have a high clay content, you will need a liner to retain water. You can try to find a pre-formed liner, but it has to have the varying levels or it won't attract dragonflies. You are better off digging your own levels and using 45 mil PVC, polyethylene, butyl rubber, or EPDM rubber pond liner.
After filling your pond, if your water is chlorinated, let it sit for a day or two before adding plants to allow for the chlorine to dissipate.
Place a few large, light-colored stones near the edge of the pond. This provides a perch and warming station for adults. Logs or large tree branches are another nice addition. They provide another perch, a place for females to deposit their eggs, and an escape route for critters who might fall into the pond.
DO NOT add fish to your pond. They will eat your dragonfly larvae.
Here are some products on Amazon that can help you with your dragonfly pond construction (these affiliate links pay us a small commission and helps us bring this free resource to the dragonfly-loving community):