Forgot to say Ledavid by Mincha

1. Question: 

I forgot to say Ledavid by Mincha, may I make it up by Maariv?

Answer:

Seemingly it is better not to do so. However, one who does so have upon whom to rely.

The reason: We indeed find that some are accustomed even initially to say Ledavid at night, and so is the recorded Minhag Ashkenaz. Practically, however, most Poskim rule it is to be said by Mincha, which would enter its recital by Maariv into a question of saying Tehillim at night, which is avoided. Thus, it would seem that one should not make it up at night in expense of transgressing the adherence of avoiding saying Tehillim at night which is not part of the Seder Tefila. However, one who does so under the argument that it is considered Seder Tefila for some Jews seemingly has upon whom to rely.

Sources: Alef Hamagen 581:6; Divrei Malkiel 6:23-2; Kitzur Shulchan Aruch 128:2; Siddur Admur; M”B 581:2; Siddur Beis Yaavetz-additions of the editor