Question
Is it beneficial or harmful to water an outdoor potted tree by watering through the reservoir it sits in ?

Answer
Hi April, watering a plant with a reservoir (and I'm assuming that is a container under the pot that holds water) is only advised for a plant that needs copious amounts of water. Most trees don't fall into that category and you risk rotting the root ball by doing it this way. Remove the reservoir and water the container from the top, making sure to water sufficiently (until water comes out the drainage holes), then hold off until the top 3 inches are dry to touch before you water again. Mulching the top 3 inches of the container will assist in keeping the potted specimen evenly watered, but keep the mulch from contacting the trunk so that the junction of trunk and roots don't become saturated. Nick