Holly trees are evergreen plants that have dark green leaves and display red berries during winter. They are perfect to grow as standalone trees, or planted close together to create a hedge. Holly trees require little water and are fairly resistant to diseases and pests. Some indications of a dying holly tree are patches of yellow or brown leaves, stems with no leaves, or black spots. All of these symptoms can be treated effectively if caught early.
Examine the soil for too much water. Excessive water will be evident by the appearance of damp soil or standing water at the surface. Too much water causes the bottom leaves of the holly tree to turn yellow and then brown. Stop watering the plant until the soil is dry one inch into the ground. If the plant is in a container, replant it with new, dry soil immediately.
Examine the soil at the base of the holly tree to check for too little moisture. Stick your finger into the soil until the first knuckle is at the soil surface. If the soil is dry at the end of your finger, the plant needs water. Water the plant thoroughly and provide one to two inches of water once per week thereafter.
Examine the roots of potted holly trees to see if they have enough space to grow. Grasp the trunk of the holly tree and pull it out of the pot. It's fine if the soil comes out with it. If there are many roots at the bottom of the container that are growing in a circular direction, the holly tree does not have enough room to grow. Replant the holly tree into a new container that is twice as big as the one it is planted in. You may also want to consider planting it outdoors in the ground.
Look at the holly leaves carefully for signs of pests such as aphids. These tiny insects live on the underside of the leaves and are only visible upon close inspection. If you see any movement on the holly tree, spray it immediately with an liquid insecticide solution. Repeat the treatment as instructed on the insecticide packaging until the insects are all dead.