You can use last years soil, but you won't be happy with the results. Its always better to make fresh. filix.

Humm..

Well sometimes I'll admit I take the lazy mans way out and just take out half the older mix in some of my containers and add fresh soil along with perlite. I stick the shovel in the container and mix well, and then plop my plants in them.

As long as the mix drains well, this doesn't seem to affect their growth, as long I feed them on continual basis. They actually do pretty good and I save lots of money.

I usually provide fresh a 5.1.1 mix in particular if I should run out or want to start fresh.

Caution: I only use this technique for my annuals and or seasonal plants.

Hey Mike! I tried using old soil one year. I did a comparison. Same plant same pot right next to each other. The one with the fresh mix did better. I never tried mixing old with new. Then you have to worry about pathogen's. My brugmansia are in full bloom right now. They are still inside and the fragrance is overpowering! Every bit as strong as my night jasmine!. Happy growing. filix.

Hey Felix! You gotta love our weather, right? Sheesh. They have been saying sun by Friday all week and me thinks they are wrong AGAIN..lol

Your right. For me certain plants I will not put in older mixes mixed with new which is why the caution sign was put there, but many of mine never have a problem, especially the flowering annuals, and grow just as nice.

I think the key for my success is a good fertilizer regimend and making sure the mix is as free draining as I can get it while it holds good moisture for a period of time. I kind of have the 5.1.1 mix in the back of my head and go from there, since all the last years container soils were originally the 5.1.1 mix anyway. It seems that even last years mixes still have great structure, minus the pulled out plants or course.

To name you few: Marigolds, petunias, impatients, lettuce and a few others. I guess it all depends on the type plant? In fact all my flowering annuals do very well.

Felix, I just have to see your Brugmansia! Please send me an e-mail. I have a cutting of one that I managed to root and had no idea what to do with it. So I planted it into the ground since I would love to see it take off. So far so good!I hope I get flowers on it. Is any particular color more fragrant than another? I heard that white is fantastic. Lucky you and up here in New England with such a lack of sun lately.
Can you please e-mail me privately since I don't want to go off subject here. I would love to chat with you about this.

Mike;-)

Thanks all for your great advice and education...very generous of you to take the time! I will definitely change my potting habits and use fresh soil...I might put a layer the old soil in the bottom of some....after I have aerated it. I only grow annuals in the baskets�usually put them on tables on my deck.
Again ~ THANKS

This topic comes up a lot. I started using a pine bark based mix I think the summer of 2005 based upon that article Al started. My entire container garden consisted of bad practices -- topsoil and compost. Plants still grow in that stuff BTW. Due to the size of my container garden at the time (~200 cubic feet), it was impractical logistically to convert everything to pine bark in one fell swoop. Most of my container garden is on a rooftop so just hauling the material up there is a chore. I made an executive decision to do 50/50. 50% of the mix uses last year's mix and 50% uses pine bark (plus the requisite perlite and other stuff). Gradually, over the years, the entire garden is practically 100% pine bark based. I still reuse 50% of last year's mix and have noticed that pine bark can last a bunch of years. Certain containers that support forgiving plants like morning glories, I only change those containers out every three years. The pine bark does hold up year after year.

If you're dealing with a couple of baskets of plants just use fresh mix since it's not that much. If you have a lot of containers and want to limit the amount of work come up with some way to recycle last year's mix. When you introduce new pine bark or whatever into your container garden, an equivalent amount of container mix must be disposed of for whatever new stuff gets introduced. This also becomes a problem for those of us (like me in the city) who have nowhere to put it.

Luckily, now, my discarded mix every year is better than the best top soil any big box store has to offer so I have plenty of takers for my discards to put in their in ground gardens.

Below is a link to photos of my rooftop garden over the years. The last garden album I kept was 2007 but it'll give you an idea of what it looks like. This year I'm going to put up a new garden gallery -- that is if I have a good year of course. :-)

Here is a link that might be useful: Click on the Gardening Albums