Can you kindly tell me if I need to throw out all the soil from last year pots to start planting herbs etc this year.
I was reading where one has to throw out old soil in pots.
Thanks.
Thanks for contacting the Toronto Master Gardeners.
You’ve raised a question that many people have when planting herbs/annuals in containers. What should one do with the potting soil from the previous year? The simple answer is that the soil does not need to be thrown out; it can be reused or recycled. [However, if the plant material from the previous year was diseased, the soil should be disposed of and the containers cleaned thoroughly].
Depending upon the size of the pots or containers, it can be reused in different ways.
Generally, whether the containers are on a balcony or on a patio/deck, you will need to use potting soil. If the containers are relatively small, simply empty the pots into a bin or large container and mix it with new potting soil. Then put that mixture back into the pots and plant your herbs. Of course, you will need to add fertilizer or soil amendments throughout the growing season–(all container plants need additional nutrients).
If the containers are relatively large, empty just the top few inches of the soil into another container; then add and mix in some new potting soil and return that mixture to the pot. All the soil does not need to be replaced. This method is particularly useful because it will reduce the number of bags of potting soil and amendments that will need to be bought and transported onto a balcony space. Unless the previous year’s soil had a disease-affected plant in it, the soil can be recycled by adding new potting soil and/or compost to it.
If you have a compost bin, you can also recycle the used soil rather than throwing it out–compost is an excellent amendment for any plant in a container or otherwise.
We wish you a good gardening season.
For further info:
https://www.springpot.com/blog/reusing-potting-soil/
https://www.gardensalive.com/product/can-you-reuse-potting-soil-from-your-containers