Crochet - Granny Spike Stitch - leaves fewer gaps, because the second double crochet is crochet through the top of the second double crochet of the row below. Possibly use a dc,tc, dc pattern in the clusters? From Do It Darling.
A great graphic reference for basic advanced crochet stitches. A quick glance can help during new or more difficult projects. Chain Slip Stitch Double Crochet Treble Crochet Half Treble Double Treble Treble Cluster Treble P