A beautiful collection of containers at the Berkshire Botanic Garden – http://www.berkshirebotanical.org
Funky Provincetown Box for Sun
At this time of year some folks are eyeing their pots and planters, deciding which annuals to use in the coming season, and many in the south are planting containers right now. Further north we’re dreaming and scheming, doing research and ordering plants or seeds. But everywhere the question is always the same: “Do I have to use new soil in my containers and boxes every year?”
Faced with the job of emptying out last season’s containers, most of us are tempted to take the easy way out. It would be less work, and a reduced expense, to plant in the same soil. Now, I’m all for taking it easy on the back and wallet, but you’ll be a more successful gardener if you use fresh potting soil every year.
Last year’s dirt is filled with roots. Whether you grew a pot of flowers on your porch, window-boxes filled with annuals, or containers of herbs, the roots of those old plants now fill the available space.
Angelonia, zinnias and nasturtiums
If you stick a trowel in those containers, you won’t find loose soil because last season’s roots don’t break down so quickly. Placed in that root-congested area, your new annuals won’t get established easily. It’s as if you were trying to move your furniture into a new house, and the rooms were still filled with the previous owner’s belongings.
In addition to being crowded with last year’s roots, the old soil is also depleted. Not worthless, mind you…it’s still good for the compost pile or top-dressing the shrubbery. But the nutrient value is higher in fresh potting mix.
Cottage box in the shade.
Need more convincing? Well, remember that weed seeds have had an entire year to blow into those containers, and although your annuals will have a tough time growing in the old soil, the weeds will love it. Before you know it you’ll need to pull out some very tenacious weeds. Now I don’t know about you, but one of the reasons I like container gardening is that I can have flowers without the work of weeding.
New potting mix has no roots or weeds, and it’s high in nutrients. So when people ask “Do I have to use new soil every year?” I’m ready with the answer: Yes.