I've done exactly that using straws with holes cut out off them down the length. First i made a hole with a pencil so the soil wouldn't block the straw, then I just placed the straws in, about 6 of the as I remember. I did this before they sprouted so they wouldn't interfear with the roots. To be honest I don't know how much use they were, I should of had a control plant, but I had good healthy growth so can't hurt.