From the Ground Up - Pot Stuffing- or Stretching Potting soil
How to Stretch Potting Soil
The greatest trial in my garden's existence is a lack of money. Money to buy seeds, pots and soil, especially soil. Specifically potting soil.
As I have gophers (living on two canyons will do that) I grow 99% of my plants in pots. Potting soil makes up about 80% of my garden expenditures. I try to reuse my soil after my annual vegetables and herbs are done for the year. If, IF, the plants were healthy I mix the old soil with worm casting from my worm bin and a little sifted compost or sawdust (for bulk, the worm castings keep the nitrogen levels at a good level for the plants).
Then I was reading. I have this book from Storey Publishing, Week by Week, Vegetable Gardener's Handbook.The book was written to be adjusted to different regions. One suggestion stuck in my mind. It was a method of stretching potting soil. The pots were filled (about 2/3) with shredded leaves and then covered with soil. As the leaves decompose the plants are fed and at the end of the season it is excellent compost.
But what should I do? The only trees l have use their own leaf drop as mulch and food. I stood gazing at my garden. I wanted to try this. And then it hit me. Right in the face, literally.
Five feet tall some of them with horrible root systems and a plethora of seeds. Perfect, then I thought, what about the drainage holes? Don't weeds grow out of them occasionally? No problem, I have rabbit bedding and sawdust. If that isn't available, I can use weed barrier cloth as it drains.
And so 'pot stuffing' begins!!! First 3-4" of sawdust or bedding is placed in the bottom of the pot. Then weeds are cut up into pieces and tamped lightly to settle (Settling has not effected drainage in my experiences). I usually stack something heavy to press it down and then add more. My pots end up about 3/4 full and then I add re-amended or new soil.
Before adding the soil, I sprinkle diatomaceous earth across the top of the weeds. This helps to prevent the pillbugs and earwigs from root munching.
As the plants grow and the 'stuffing' decomposes there will be a dramatic drop in the soil levels of the pots. There are a number of ways to handle this situation. If it is my perennial plants, I carefully lift them (having prepped a new pot with the 'stuffing' to lift it about 1" below the pot lip) and place them in the new pot. Tomatoes and corn don't mind soil around their stalks as it adds stability to the plants, so I layer potting soil on top.
Since most of the organic matter I have discussed is high in nitrogen some plants (i.e. vegetables grown for their fruits) may require supplemental phosphorus and potassium. Even with the added organic matter in the base of the pot, the fertilizers in the soil will only last about a month so continue to feed the plants about once a month with a granular fertilizer.
According to the journal from which I took this idea, the authors amended their garden beds with the pot mixture at the end of the growing season. However, if my plants stay healthy and bug free (i.e. mealy bug and wooly aphid, both of which like to hide in soil) I mix the old pot soil with some peat moss and perlite or pumice and reuse it! It doesn't take much, I buy one bale of peat moss a year and and the perlite is still in the used up soil. If it isn't enough then add it.
Plants I use lightly or I DO NOT use at all:
- bermuda grass : it MUST be completely dried out or it will sprout from every joint
- shredded paper: it mats and will not drain properly (never use the shiny pages, the plasticky coating is not good for plants, if it is not shiny and carbon paper, I put it in my worm composter)
- shredded cardboard : same as above, unpainted cardboard only
- leathery leaves : I use them lightly as they don't break down quickly. If it is a large pot I am filling for my hardy perennials, the leaves and twigs are good as they are slow in breaking down and last longer. Leaves include - star jasmine, camellia, indian hawthorn, ficus benjamina and stephanotis.
- leaves that stunt growth : Brazilian pepper, eucalyptus and pine
- poisonous and diseased plants
Pot Stuffing is a matter of trial and error. For every area there are different plants and resources. The urban environment can make it even more difficult to find bulk materials. Some houseplants may work. Cordyline and draceana, palm trees and coffee plants come to mind. Start small and experiment, research your area and choose your plant material.
Please let me know if this works for you!!!!
The book I read: Week - by - Week, Vegetable Gardener's Handbook by Ron and Jennifer Kujawski 2010 Storey Publishing ISBN : 978-1-60342-694-7