Question
We planted arborvitae 2 years ago, ten at my mother in laws home and ten at our home about 15 min. north. Hers are planted on a small hill at the rear of her property. She waters them faithfully. We water ours occasionally. Ours look wonderful and are thriving. Hers have large amounts of little light green pods that look like seeds that did not open. These seed things are weighing down the branches of the trees and they look very droopy all around. She is so dissappointed in hers and we can not figure out what is wrong. What is the difference?

Answer
Hi Wendy, If they are indeed seeds (actually they are cones), large quantities are often produced when plants are under stress.  On a plant that has only been in the ground for 2 years, I'd suspect a water issue.  Too much or too little could be the culprit.  If they are taking on any bronze color in the summer, it's too little.  They need a lot of water in the summer and since they are on a hill, they will dry much more quickly than yours.
Check the growths closely, cones will all look alike, if they are irregular in shape, it is an insect. Galls form around a number of internal insects.  If it is an insect, either spray every 3-4 weeks with Acephate starting as soon as new growth starts through fall, or drench the root zone with Imidacloprid once in the winter when the ground is not frozen for season long control.
If you determine they are cones, next year when you see them form, a light shearing to remove them should solve the weight issue. Jim