A rheological and interferometric study of agarose sols and gels at different concentrations is reported. At concentrations smaller than 0.12% (w/v) agarose solutions behave like non-Newtonian fluids, while at higher concentrations they do so like viscoelastic gels. It is confirmed that agarose gels avoid mass and heat convective transport as well as sedimentation. We also find that agarose solutions at a concentration as low as 0.04% (w/v) are able to overcome buoyancy and crystal sedimentation. These results broaden the potential use of agarose in protein crystallization techniques.