It is safe to use cannabis with Lexapro. Possible effects that may occur in conjunction are: Lexapro, a SSRI, may increase the affect and duration of cannabis; in rare cases using a SSRI plus cannabis can lead to a psychotic event described as mania (usually via edibles or with Bipolar disorder).
Any doctor would tell you it isn't safe to mix substances such as one as minor as marijuana in comparison to other drugs. I take Lexapro https://pillcomparer.com/lexapro-vs-wellbutrin.html for depression/anxiety and smoke marijuana daily while on it. I haven't experienced a single negative side effect. But your pharmaceutical drug in question is different than mine. I'd say you'd have to give it a try yourself, and not go off of what others tell you. Everyone's body reacts differently to different substances, especially when they are mixed. If you do decide to try a combination of the two, I'd suggest smoking a very minimal amount of marijuana to begin with, and slowly work your amount of green smoked from there. I'd also suggest having a buddy around while you do so, just in case something happens to you and you need medical assistance. I hope that helps a little!