Your "problem" is probably part of both environment and genetics. Fertilizer and rainfall will help. Variety will probably be a bigger factor. If your vines are a number of years old, they may be genetically inferior. When growers raise fruit commercially, they replace plants often with better and newer varieties. If you plant seeds they may not come true to variety. They may cross pollinate with others nearby or revert back to genetic parent characteristics. Remember those Gregor Mendel matrixes (or is it matrices) from 10th grade biology? Either buy new vines or take cuttings (clones) of plants you like.

Petals from the Past down in Jemison sells several different varieties of Muscadine vines. They also sell fruit from different types, so you can sample them before you buy the vines! I need to get my act together and build a couple of trellises, because I am 100% hooked on these things. And they're kind of expensive to buy. They're also very healthy, with higher levels of beneficial antioxidants than typical table grapes. I love the sour skins, too!

I have a Question on what time of year I should plant new vines. I live in Pensacola, FL

My vines are 50 years old! I believe the nurseries have new vines in the spring. They should have the big ones. Scups are dormant during the winter. I prune mine then and clean them up and fix the trellis. They are just now ripe and after the dryest summer on record here in AL they are delicious!

Most experts recommend layering for propagating muscadines. Take a piece of vine and make a "U" shape and stick it in a pot of soil, than put a rock or something on top of it. Do not cut the vine from the parent plant. Gently check it next spring for new roots. If you see roots, then you can cut it from the main vine.

If you're looking to buy some, I bought "Jumbo" and "Triumph" from Ison's vineyard last year and they look great.