April maybe a little early. Depends on what kind of a year were having. If you can cover them if the temps start getting below 45 or so you should be ok.
They usually take longer to grow outdoors than they do indoors too so take that into consideration. It really is a good idea here in the NW to have a way of covering. Ecspecially during the end when the buds are getting nice and full. They're more suseptible to bud rot then.