I'm redoing a backyard on a row house. The yard is 19 feet wide. I
had to dig down the yard about 18 inches in order to move the soil
line down below the sill on the house. I'm going to end up having
raised beds on the sides where I did not dig down.

For an event coming up in June I need to get some sort of retaining
system in. I need something temporary because I don't have time to
build the final solid retaining wall before hand. Any suggestions?

Thanks in advance.

For an event coming up in June I need to get some sort of retaining
system in. I need something temporary because I don't have time to
build the final solid retaining wall before hand. Any suggestions?

Rent some concrete formwork?

Don't forget that a ditch like that will be a hazard to partygoers.