Can you have non wiccans at your spring equinox ritual?

When I worked with a coven, equinox and solstice festivals were actually the only ones to which a non-initiate might be invited. But never to one of the full Moon or cross-quarter rites.

Why not if they want to and agree with what is going on and want to participate.

So long as the non-Wiccans were open-minded, and anyone else at your rite was comfortable having non-Wiccans present.

Sure, if they're open-minded about it. I know too many non-Wiccans who feel uncomfortable about us Wiccans, so it depends on whom you invite. An early Happy Ostara!

It depends. If you're in a coven, then it probably has specific rules about the attendance of initiates/non-initiates (I know certain covens where even the first degree initiates cannot attend all rites yet). Even then, it's best to make sure that all of the members of your coven are comfortable with this person (perhaps have a get together prior with Wiccan and Cowan friends so that they could get the vibe for one another).

If you're a solitary or non-traditional Wiccan, then whatever goes along with your own beliefs would be the way to go. Just make sure that your friend knows not only what you believe in, but that certain things may even be very different from what other Wiccans believe.