Set default date in On Load to specific date (not current date etc.)

Set default date in On Load to specific date (not current date etc.)

 I have a garden app that uses a "last frost" date that is always the same for each record.  Can I put code in On Load of the form to auto populate a specific date into a date field.  Other forms have lookups back to this form that fetch this date and perform calculations based on this date.  Example:  Planting Date = lastfrostdate.addDay (input.prepostlastfrostdays)  Right now each time a plant group is added the user has to choose the date and it would be quicker if that field could have default data and maybe even hidden.