Rainy conditions and lack of time have left my Hosta beds in a mess. They are well established and very hardy plants. I intend to pull the largest weeds and use a post emergent on whatever is left over. I would then like to use Preen and mulch immediately after. Do I need to wait a certain amount of times between steps? Or can this all be done over, say, a week give or take a couple of days? Thanks in advance.
Knowing which weeds you have is the key to success. Some spread only via underground roots. If that is the case, a pre-emergent isn't necessary since it only works to prevent seed germination. Glyphosate, still the safest herbicide, painted on leaves with a brush (I use foam brushes) usually works well if you are dealing with an extensive root system. After application, cover the weed with a can or plastic bag until the herbicide dries so it doesn't come in touch with your hosta. Apply pre-emergent if you wish and water it in then put down 3"of mulch . Pre-emergents are usually applied in early spring since many weed seeds are floating in the air then. Read instructions, but it is often necessary to re-apply 3 months later. Once in a blue moon, it is necessary to lift the hosta and get all the weed stolons or rhizomes out from entanglement with hosta roots. Obviously, this is worst-case scenario.