Cedar, pine and many hardwoods are suitable for an outdoor picnic table. Many people use pressure-treated pine because it's durable, very affordable and lightweight. Cedar naturally repels insects and has beautiful features. It also withstands outdoor use very well, making it a popular but more expensive choice.
Cypress, teak and native white oak are also great choices for outdoor furniture because they are resistant to moisture and rot. Other types of woods such as locust or acacia may be used, but they are much heavier than lightweight pine. The best type of wood for any outdoor furniture is a hardwood with a straight grain. These types of wood are most resistant to moisture. To extend the life of outdoor furniture, it is best to cover it when not in use.