I have a 5 foot ultra light rod that I use for trout and panfish. I had 4lb Berkeley vanish fc and I liked the invisibility, but I can barely cast it with such a short rod. I think that I'll switch to some monofilament for next year, but do you think will it really help?

Yes 4lb Berkeley xl casts much better

It will probably help a little.  A longer rod would definitely help though. 

Short rods  =  short casts

 

Long rods = 

 

I use 4# braided line. Helps also.

 

Test prove that almost every line breaks at 2 to 3 times the rated strength.   SOOO  Use 4# really about 9 to 12 pound breaking

 

The braid will take spinners twisting the line better than a mono plastic..  Braid does not form permanante coils like mono.

My ultra light is a 7' soft rod with 4# line & 2# leader for about 3' long.

 

Long accurate casts. Soft rod soaks up line breaking big fish. A light weight fly rod can do a good job as a ultra light rod.  Check that it will hold your reel before buying.

IDK, I use a 5' MIcroLite and have no trouble casting small, 1/16oz. jigs and Beetle Spins.  What size reel and lures are you casting?  The only time my distance and accuracy become an issue is when I suspend a jig or small tube under a bobber, but that's just the nature of that animal.

Thanks everyone. I know a longer rod would help but I got this one to use around lots of vegetation on the bank. I'll try the mono.

A full spool (not overfilled), softer/lighter line, larger arbor, longer rod and appropriate power rod for the bait weight each aid in casting distance. Change any or all as conditions allow and you should see improvement.

Nanofil casts really well.  Need to tie a leader, though.

First thing I would do is switch out that Berkley Vanish line. I would not use it even if it was given free to me. To me it is stiff like no other but I have not tried it at 4lb test.

I don't think mono would help but you could deffenetly increase your distance w/ a longer rod.

Thanks everyone. I know a longer rod would help but I got this one to use around lots of vegetation on the bank. I'll try the mono.

I wouldn't use a UL where there is a lot of vegetation, just not enough backbone.  I do use a 5' Ul quite a bit in open water ponds, I've got braid on my reel and it casts just fine.

Shorter rods are very capable of getting very respectable distance too. The shortest rod that I use on a regular basis is a 5'10" Loomis Smallmouth Topwater Rod and that rod will sling a Super Spook Jr a long ways with braid. IMHO, the line and lure are more important to distance than rod length.

I carry 2 5' Fenwick HMG rods that I use for finesse fishing.  They handle grubs and my buck tail jigs very well.   I have caught bass to 6.5 # on them.  I have Shimano Symmetry 1000 reels mounted on them.  There are only 2 kinds of line that I use on these reels; Original P line in 6# test and Power Pro braid in 8/1.  I use the braid most of the time but switch spools to mono when it is windy.  This has worked for me since I bought the setups in 2001.  I don't use them every trip but they never leave the boat.