Hose out and set in a safe place where you can work with RIT dye and stay out of trouble.;
, this stuff is permanent and extra tough to get out of anything...including your skin.
 Your best product is the limestone gravel they use with tar on country roads (sans the tar of course). Be sure the gravel is very dry or the liquid will not soak into the pores of it, as those pores will already be full. Usually about 10 minutes with some agitation is good enough. Super smooth gravel like river rock takes forever to dye

, Dry and spread, or spread and allow to dry.
Get a wheelbarrow that does not leak and clean the bed very, very well.
Buy the color RIT dye you want from any grocery or super center type of place and mix it up in the wheelbarrow bed, but don't splash.
Add gravel to bed of wheelbarrow.
Use a cleaned shovel and remove gravel already dyed, draining liquid as you do by tipping shove against the side of the wheelbarrow as gravel is removed.
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