By Wendy Blair, Master Gardener
Last year’s potting soil may look ready to re-plant, but chances are there aren’t enough nutrients left to feed your new plants. Over the growing season, macronutrients are leached out during watering and are used up by hungry plants. Buying new potting mix for all your planters every season can be expensive, and it's not necessary! You can replenish nutrients to your old soil by adding compost and organic slow-release amendments.
Here is a list of items you will need to replenish the soil in your planters.
Supplies:
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Container with old soil
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Fresh Compost
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Shovel
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Large container for mixing
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Pretty plants
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Organic nutrients: we used our OMRI certified Blooming Boost which is a phosphorus blend that encourages flower production
Method:
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Shovel or dump out old soil from your planter into a large container
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Incorporate compost into the soil in a ratio of approximately 1 part compost to 3 parts potting mix (you can eyeball this, a little more compost won’t hurt your plants)
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Mix together well with a shovel or your hands
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Place amended soil back into your planter and water in well
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Wait until all the excess water has drained before planting (using a planter with a drainage hole is imperative)!
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Add nutrients
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Plant your new beauties
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BONUS: you should have some amended soil leftover to use in another planting project!
Apply Blooming Boost at a rate of 2.5 TBS per square foot (we used 2 heaping tablespoons in this planter)
This planter is ready for the season! (Dianthus and Dusty Miller were purchased locally at Osuna Nursery)
*EXCEPTION
Do not reuse your soil if disease was a challenge for your plants last year. Bacteria and viruses can live in your potting mix long after your plants have gone. Many pathogens can survive winter temperatures and years without water and plants to feed on. It’s possible to kill the pathogens, but for some gardeners, it's not worth the risk. You may not notice the problem still exists until far into the new growing season.
In this instance, it is best to dump the old soil, clean your planter with a 10% bleach solution, and start over with fresh potting mix. We recommend our Soilutions Potting Mix, made with coco coir, Soilutions Compost, pumice and worm castings. It’s available at our soil yard in the South Valley and at fine nurseries around Albuquerque.
