Container gardening is the perfect option if you are short on space, commitment level, or time {in any combination}. So, when Dig for Your Dinner reader, Renee, sent in a question about how to best tackle potting soil every year, I thought I would turn it into a post, and spread the word.
She wrote,
Hi Mavis! As a fellow greenhouse and container gardener, I’m curious how you prep your ‘captive’ dirt for planting. Do you replace the dirt in your containers every year? Amend it and mix? Fertilize and cross your fingers? (My worst idea of the bunch) Thanks in advance. Renee
Container gardening is a bit different than your standard bed gardening. For one, you have less space. Two, you have to baby the dirt more. Each growing season takes a lot of nutrients out of the soil, and since container gardening, well, “contains” the soil to a small space, it ends up getting sucked dry a little easier.
I usually toss the soil from my planting containers into my garden boxes and add new potting soil/compost mix to the pots. I always add compost into my garden boxes, so it enriches the dumped potting soil on that front. I have found that straight replacing all of my container with new soil yields better results. On years when I get lazy {or too cheap}, I notice a negative difference in overall plant production and kick myself.
If you don’t have garden boxes to toss the old potting soil, there are still options. You can amend the soil in containers one of two ways {the second being my preference}. First, you can replace 1/3 of the soil yearly. This will provide a little extra nutrients for the growing season and prevent you from having to “throw the baby out with the bath water,” so to speak.
Just shovel out the top third or so of soil and add new. Try to mix it with the remaining soil the best you can before planting. Second, you could dump the soil from your pots into, say a wheelbarrow, add compost {and fertilizer, if you are so inclined} and mix it in well. You’ll end up with more dirt than pots, but this allows you to really mix the old dirt in with your amendment.
Ultimately, replacing at least some of your soil will flat out give you better results. You could try “crop rotation” in the pots to keep the soil healthy {plant tomatoes one year {nitrogen sucking}, beans {fixes nitrogen to the soil} the next, etc.}, but I can’t really attest to that in a container gardening situation, because I just haven’t ever done it.
How about you, do you replace your soil? Amend it? Ignore it and see how long you can ride it out?
~Mavis
Gardenpat says
We are just teaching a class on making planter boxes using an open, decorative “box” made from recycled wood pallets that surround a plastic bucket (recycled and free from a local bakery). One of our ther presenters raises worms for his garden and figured out how we can add worms to our buckets that will help “renew” our soil in the buckets! Didn’t take much to modify our containers to have them “worm-friendly”!
Tracy says
I have several 2′ X 2′ X8′ container gardens, raised several feet off the ground on legs. I planted them with an amazing product called Bumper Crop to start with. (The richest, most nutritious stuff I could find, with terrific texture and tilth.) Each year, in late September, I plant the beds with green manure (mustard is my favorite, but there are many for different climates), which gives something green to look at until it is literally covered with snow. Then, come spring, I simply cut the plants off at ground level and fork in the roots with the fixed nitrogen balls attached to them. The green manure protects the soil from erosion or leeching of nutrients, adds fantastic amounts of nitrogen, and the light roots add texture and lightness to the soil when I hand fork it in in Spring. I also add rich compost and some organic (I like Espoma) fertilizer before I plant the container beds again. Seems to work great. One year, I may add a layer of manure on top in fall, instead of the green manure, and let it decompose over the winter. The frost and freezing breaks it down beautifully. This approach has worked for me for many years.
Phyllis says
For my raised beds, I treat the soil as if it was an in-ground garden, adding compost, worm compost, mulch and occasionally cover crops…no chemicals. The soil is awesome and the yields are great.
All my pots are quite large but each year I dump out all the soil onto a large tarp and add (by volume) about 1/4 shredded leaves, 1/4 worm compost to the existing soil. Then refill the pots all the way to the top. Every 4-6 weeks the soil will have compacted enough to add about an inch of additional worm compost. I do this every year. Never had a problem, never add chemicals. The worm compost is free from my outdoor worm pile that produces about 70 gallons a year. The pile is a small mound behind my roses about 10′ long x 2′ wide x 1′ high, covered in shredded leaves no one can even see this amazing fertilizer factory! Can’t imagine the cost of replacing the soil and buying fertilizer each year. It’s been 5 years and will finally have to add some additional soil this year.
Sue R. says
A tip for anyone who lives near a Fred Meyer store–every spring (April?) they have what they call “Fuchsia Day.” You bring your own pot, buy any plant you want and they plant it for you in their good, fresh potting soil. I’ve done it two different years and the soil is great! I don’t worry about bringing my “special” pots–but just bring any plastic ones, buy a plant or two and then repot/arrange when I get home. The little extra work is worth the free soil 🙂 (I’m not being dishonest–I use the soil, just don’t want to carry heavy pots to the store.)
Tom says
Every year I take our large pots and dump the soil into big water garden whiskey barrel liner we have. On top of the soil I add a handful or two of garden lime, 1/4 to 1/3rd of a bag of steer manure, 1/4 to 1/3rd of a bag of garden compost and about a 1/3rd of a bag of black gold worm castings. Then I mix it all together using a small bladed/long handled shovel.
This method seems to work great and this year I think I will try adding some rock dust for the mineral value. You are right though about having more dirt than pots using this method. It has made me buy more pots and go to vertical gardening. Don’t know what I’ll do when I run out of space, probably start giving it away to the neighbors.