I learned the importance of sterilizing pots and planters after losing an entire crop of cucumbers to the mosaic virus.
They seemed to thrive in their little pots before I moved them into larger containers. I couldn’t figure out why all of my cucumber plants died. Then they went through a wonderful growth spurt and were even starting to flower. Sadly, the cucumber mosaic virus took them all out in a matter of days.
I’d never met this problem before, so I asked another gardener friend about it. She immediately asked me whether I’d sterilized the containers before transferring the seedlings. “No…? Should I have?” Oh yes. Sure you should.
Why You Need to Sterilize Planters and Pots
It’s fascinating to learn that there’s always something to learn about growing your own food. Also, much like necessity is the mother of invention, a person only becomes aware that they need to learn a skill when they encounter a problem they need to solve. Take, for example, my experience with mosaic virus.
In the growing season, your plants can be attacked by various pests and pathogens, including the evil cucumber mosaic virus. Many of these parasites reside in the soil.
And even better, these soil-borne pathogens do not just live in the dirt. In fact, they can hide inside your pots and planters as well. Additionally, they can go dormant, only to emerge and kill your plants once the weather warms up.
To prevent this from happening, you need to make sure that all gardening utensils and planters are cleaned and sterilized.
How to Sterilize Planters, Pots, Trowels, and More
The best way to clean this baby is with a two-step process.
The first must be done at the end of the growing season before all your plants are put away until the following spring. The second must be performed just before the seedlings arrive at their larger containers.
Compost spent plants you have grown and harvested. If your soil is still healthy and hasn’t been contaminated by any pathogens, then you can toss it in the compost bin so it can absorb the nutrients you add over the winter.
Please note that if you have ever dealt with blights or viral infections, it is best to sterilize the soil and dispose of it to protect the plant. Pour boiling water into the containers, saturating the soil completely. Repeat a few times.
You can find soil recycling services around you by doing some research. They will be able to sterilize soil completely, making it safe to reuse.
Wash Everything Well Before Storing It
Immediately after emptying the containers, wash them thoroughly with hot, soapy water. Also wash all the gardening tools you used during the growing season—spades, trowels, snips, saws—pretty much anything that came in contact with the plants or soil.
In addition to drying these items, the sun will also disinfect them. Lay these items out on towels or tarps to dry in the sun. When the items are dry, wrap them in newspaper or burlap and store them somewhere dry for the winter. I store my supplies in my shed, but if you don’t have a shed, keep everything in a closet, garage, or basement room.
Clean Them Again in Springtime
For plants grown from seed, the best method is to count backward from your last frost date to determine when to start the seeds. That way, they’ll be ready to plant outside as soon as the weather is warm enough.
Get prepared for planting in spring: sterilize pots, planters, and tools a week in advance. Wear protective gear! You’re going to be handling caustic materials, so take precautions. We recommend rubber gloves, eyewear, clothing that won’t bleed, etc.
Give Them a Bath
Okay, first things first.
In order to sterilize everything, fill the bathtub with warm water. Add bleach in a ratio of 1:19 (hence, if you use a one-gallon jug of bleach, use nine gallons of hot water to dilute). Warm water rather than hot water ensures that you won’t breathe in bleachy steam.
Remove the burlap or paper covering from the pots and planters and put them gently into the water, rather than flinging them in. That way, you can avoid getting splashed. If you can fully submerge the pots and planters, that’s ideal. After 15–20 minutes, let the bleach wash soften up the tissues, which should kill off any bacteria or insect eggs lurking in the cracks and crevices.
In the event you cannot submerge them completely, let them sit for 15–20 minutes, and repeat the process after turning them to ensure each side soaks for the appropriate amount of time.
Using trowels, spades, and other tools in the same way is a good idea, as it’s hard to be too careful here when it comes to cleanliness.
After the soaking is complete, drain out the bleachy water and replace it with soapy water. Scrub all surfaces with a cleaning brush, then rinse in hot water.
After that, you should thoroughly dry each piece and go ahead and store it in a warm, dry place for at least one week to let any residual bleach evaporate.
By the end of that week, they will be ready to fill with soil and seedlings (or directly sown seeds, for direct-sow species).
Avoid Cross Contamination
Keeping your garden free of contagious pathogens doesn’t just mean you should keep objects out of it; you should also be watchful of visitors in there as well.
If you have put the time into sterilizing planters and pots, you don’t want your plants contaminated by interlopers. It may seem cozy, pastoral, and charming to have gardening and farm friends over for a visit, but remember that people can carry viruses and insects.
It’s not okay for them to get close to your plants if they have wiped their hands on their clothes after working in the garden. Diseases and pests can jump over.
When you and others other than your immediate family will be visiting your garden, let them go through a decontamination station first. Provide spare apparel and boots to ensure they do not wear their own clothing in your space.
I know of someone whose entire garden was destroyed by a red mite infestation after a neighbor’s dog wandered into the enclosure. Secondly, ban any domestic animals from your garden except your own. Those pathogens and insects won’t just ride our hosts.
Use Healthy Soil
Clearly, sterilizing tools, pots, and containers for plants would be wasteful if they were re-contaminated with dirty soil.
Ideally, in a garden environment, you will have a gorgeous pile of healthy, nutrient-rich compost to draw from. However, if you do not already have a compost system, you may have to buy new soil from the local garden center.
If possible, choose high-quality soil and make amendments accordingly. For example, carrots and other root vegetables need a lot of soil amendments, leafy greens need lots of nitrogen, and heavy feeders such as melons and squashes need lots of organic matter.
Maintain the health of your soil by clearing fallen leaves and other debris as often as possible.
Ladybugs and lacewings act as natural predators, helping to keep unwanted insects under control. Feed and water each species appropriately and don’t overwater anything. When you notice the first signs of soil-borne pathogens appearing on your potted plants, you should act quickly. Burn the plants right away, but do not put any of their parts into your compost.
The contaminated soil should be removed and disposed of, and the container treated with bleach immediately.
Additionally, be sure to clean and disinfect the area where the planter was sitting to prevent a virus from spreading to the rest of your plants. As long as you’re careful, you shouldn’t have to worry about the rest of your plants getting sick.
Keep in mind that prevention is better than cure: the better your efforts are to keep the environment clean, the less likely it is to cause damage to your plants.