More than 1,000 volunteers got down and dirty by planting 20,000 trees at Memorial Park on Saturday.

The volunteers celebrated Arbor Day with the mass tree planting.

"Oh, it's great. It's fabulous and this is a great day to be out in the park," said Anita Taylor, a volunteer. "The temp is good, we have a little mist. It's very cooling and comfortable."

The trees are needed in Houston to replace the ones that died because of the summer drought.

"This is a great start," said Joe Turner, the director of the Houston Parks and Recreation Department. "It's just a start."

Turner said replanting trees would be a multi-year process.

ExxonMobil employees served as some of the volunteers.

"We, as a city, normally don't have a tree budget. It's because of volunteers and partnerships that we're able to do the plantings," said Turner.

Even Houston Mayor Annise Parker rolled up her sleeves and grabbed a shovel.

Trees were also planted at Hermann, Mason and McGregor parks. About 25,000 total were planted Saturday in Houston.