Hello, I had 2 coleus' in these pots that did not grow well at all last year, but thrived the previous year. Should the pots be emptied and cleaned/sanitized (with what) and reused? Is the dirt reusable? Really appreciate thoughts.

I never have good results reusing previous year's potting mixes in containers. The first year I tried it nothing grew well. I'm normally taking pictures all summer, not one photo that year. I never bother sterilizing or scrubbing out the containers, just replace the potting mix with new stuff. If you have a known disease or problems, then I would, otherwise it's never been necessary.

There are numerous videos around how to reuse potting mix by filtering out the roots by sifting it, mix it 50/50 old with new mix, but the time and space needed for that just isn't something I can manage with 40 large containers. My potting mix is completely filled with roots when I take them down in the fall, I have to saw through the roots of the bigger pots just to be able to break them up into manageable pieces I can pick up to toss.

Composting the old mix might be an option if you have room and a place to do it. I don't have a space I can dump up to 30 cu ft of potting mix though to do it on a typical suburban-sized lot. I wish I could find a way to reuse it, more plants I could buy.

I recently dumped out a few pots of workable used mix onto a tarp, mixed in a bunch of perlite, a few scoops of bagged manure and several handsful of time-release fertilizer and refilled the pots. I'll use those for tomatoes and annuals. Sometimes I also add coco coir, compost or worm castings, depending on what's handy. I think the important thing is to make sure the old stuff isn't beaten to dust and still has enough structure to drain well. Also, it's important to add fertilizer at regular intervals all growing season.

Many of my pots end up like Nancy's — completely solid with roots. I don't even try to reuse those.

I also use dirt more than one season, trying to discard any fine dusty portion ( if it's dry enough to) and adding something for structure/ drainage. I'm no pro but do well enough to justify my stingy ways. Potentially fussy plants and seedlings get fresh stuff. Beasts like Alocasia can get whatever with roots and junk. And I never sanitize, scrub etc. Though I don't like the look of that yellow crust on the bottom of your pots. That I would scrub off.

I pretty much do what Zoe does but do try to add some compost. The completely full of roots pots are dumped into the compost pile.

I should add that my planters are on a drip system hooked up to a fertilizer unit that gives a small dose with every watering. I also put time-released fertilizer in each pot and earthworm castings. None of that helps the potting mix that is filled with last year's roots though. If you can't break the ball of potting mix apart because the roots are holding it together that well, I don't think you can reuse it unless you compost it.

I usually turn my container into a wheelbarrow and add some new potting mix, compost, manure, and perlite.

If I have roots in it I screen it through 1/2 inch then 1/4 inch hardware cloth to clean any chunks out.

Most large planters don't need sterilizing. If you are using small pots with orchids or other ornamentals which are susceptible to virus soak them in a bleach solution.