I found that I obtained poor phage growth on plates using either LB bottom agar or an agarose overlay. I use NZY medium (which contains added Mg++) and NZY top agar. For phage DNA preparation I use liquid cultures as described in BioTechniques vol. 14, p. 360 (1993). PEG, SDS, and DNase are not used so the DNA usually digests very well.