I've mentioned the following extract from Angling Ways by E. Marshal- Hardy a number of times in previous posts and it is first rate guidance for anyone attempting to fish the seed in my limited experience.
Here is the extract in full for your entertainment and guidance should you be considering trying this devilishly addictive bait ~
The methods of an angling friend who is a wizard with a pint of hemp may be interesting. Many a time I have seen him count his catch by the score, prior to returning his fish to the water. At the outset he will cast as much hemp as covers his palm as far upstream as the depth of water and speed of the flow necessitate, to ensure the seeds passing down the "swim" in close proximity to his hook-bait. Having chosen his "swim" well and fish being present, the drifting seeds rouse their curiosity, but they may not take them at once. It is a fallacy which dies hard with some hemp fishers, that unless they get a bite every other "swim down" the fish are not feeding or are not present. My friend will fish steadily for twenty minutes or half an hour before throwing in a few more grains of encouragement, and this time only half the quantity. Then another biteless spell of fishing may be, and a third and even smaller peace-offering will be thrown in. Ere now well over an hour may have passed without a bite, but reward is near at hand. Reducing his "free feed" to five or six seeds every few minutes, he gets his first bite and a nice roach finds its way into his "keepnet." This is the signal to stop throwing in more hemp - time and again the float will toddle down his "swim" and time and time again it dips and other fish join their friends. Suddenly or gradually the bites cease, and the process is reversed. The five or six seeds are agin offered at short intervals, and so my friend will work backwards with his method of "free feeding." Almost invariably the fish will recommence to bite. There cannot of course be any rigid rules for the use of hemp, but I have described the average procedure of an an angler who is a most successful and highly expert "hemp fisherman"
Now you know!