What type of root system does the Moffett Road juniper have does it spread out or is it like a top route???? I would like to cultivate the ground around my trees but I do not want to tear up the roots???
You are correct about considering the root structure of your juniper before planting under it. Junipers have both a long tap root and a root structure close to the surface radiating out from the tree. These surface roots travel beyond the drip line but as they grow they grow downwards. I suggest you lightly mulch with fine material like shredded leaves, or rotted manure from near the tree bark to the drip line (the outer limit of the plant’s branch structure). Never pile up the mulch against the tree as this may cause bark and root rot. As your Juniper has a slim drip line, it would be wise to avoid planting under it. You may consider planting beyond the drip line but use your spade carefully avoiding as many roots as possible. Remember that plants absorb most of their nutrients from the hairy rootlets and not from the thicker roots roots themselves. Choose plants that have similar characteristics as your Juniper (eg love full sun, require good drainage and tolerates dryness). You may find these articles of interest: Area under a tree’s drip line and Moffett Junipers