Box elders are prolific seed bearers. Their seeds are distributed in nature by the wind and grow in pods. If you find a pod, you can collect the seeds by breaking it open on the tree.
Planting the Seeds
Box elder seeds are very easy to germinate using a cold frame or an unheated green house. The seeds can be planted in any moist medium. The seeds can be inserted into the medium or simply distributed on the top. Make sure you don't let the medium dry out. You should also protect the seeds and seedlings from frost.
The seedlings will start sprouting in the Spring and typically grow to a height of 2 to 3 inches within the first few months. The seedlings can be transplanted and need no special treatment other than regular waterings. Although box elders are fast growing seedlings, they do not compete well for light. Therefore you will need to ensure that the seedlings do not have their sunlight blocked by other vegetation.
Raising a box elder from a seed is a fast way to grow a tree. Within eight years, it is possible that the fast growing tree will start to produce seeds. Box elders grow well in most soil conditions, which makes them suitable to be planted in most locations.