Answer: Both pine and forsythia need full sun to grow well, so you need to make sure the forsythia will not be shaded by the pine. Also, both of these plants can grow very large in time. The mature size of your pine will depend on what kind of pine you have. A mature forsythia bush can easily be eight feet across, so you need to allow space for that as well. The reason plants do not grow well right under a pine is that the the pine blocks rain and sun from reaching the ground, and its roots are very strong competitors as well. SO you will want to plant them far enough apart that the forsythia does not end up under the branch spread of the pine as they grow and mature. I hope this helps.
Q&A Library Searching Tips