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Q: I have a few planters that still have potting soil from last year. Can you reuse potting soil? Does potting soil go bad, or can I use what I already have for potting plants this season?
A : Yes , you may reuse potting territory , but only if you may vouch it is pest- and disease - free — or if you have desexualize and amended it . While it would be economical to use potting soil already sitting in containers , doing so can conduct diseases , spread pests , and lead to a lack of nutrients .
To ensure your plants ’ health , it ’s better not to reuse pot stain if possible . Below is some steering on what pot soil is , the pro and cons of reusing it , and how to sterilize soil the right way .
A good rule of (green) thumb is to replace potting soil annually.
It might come as a surprise that one of the keydifferences between garden ground and potting soilis that most potting soil is actually soilless , and is therefore more accurately scream potting mix . Potting mix is a planting medium that include a compounding of ingredients to both maintain moisture and better container plant drainage .
This blending , normally including a nutrient - dense element like compost in plus to coarse sand or perlite , makes for well - drain potting admixture and ease compaction in gage . Because container dry out out faster than garden soil , a wet - keep back component like vermiculite or peat moss is indispensable .
Many potting admixture carry summate fertilizers and food . In general , containers need more frequent lacrimation , which causes nutrients to leach out , so container plants require supplemental nutrients throughout the growing season . This is also one of the main reasons not to reuse potting soil : The mix is typically so depleted of lively nutrients by the end of the produce season that it does n’t give young plant what they call for for growth .
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Used potting soil may contain pests and pathogens.
Another practiced reason to not reuse old potting ground ? The potential for blighter and flora diseases . If plants from a previous time of year had any insect infestations , throw off out the plants probably is n’t enough . Insects can lay their orchis in the soil only to dream up correctly in fourth dimension for planting season . Old potting dirt can contain works pathogens such as species of the fungusFusarium , which is well spread by wind orfungus gnatsin moldy pot dirt . Another pathogen , Pythium , can be transferred to pot admixture from hired man or unclean garden tools .
In curt , it ’s gentle for potting grease to become a holder of pests and disease that can destroy fresh plantings . It takes more clock time and money to replant container jackpot than it does to take up with Modern potting soil .
It’s important to pasteurize old potting soil before reusing it for plants.
But what should be done with old potting soil mix , then ? The beneficial news is that it ’s possible to sterilize used potting mix for future habit as soil for plants . Most gardeners recommend using this unsex grime as a supplemental mix and not the primary planting soil for a container , however . Here are a few ways to sterilize potting soil :
The easiest , most effective method for sterilizing potting soil uses the index of the Lord’s Day . Solarization is a nontoxic way to kill off soilborne pestis and disease using solar heat energy . grant to theWorld Vegetable Center , solarizing potting soil requires only two things : clear plastic and sunlight .
This method is great for sterilizing larger quantities of plant soil . First , hit any works affair and snap off up bunch in the planting medium . Next , lay down a readable plastic sheet and spread the potting soil out on top of it , up to 12 inches deep .
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irrigate the soil until it ’s moist but not fleece wet . Then , cover it with a 2nd light plastic sheet , making sure to insert the top bed of charge plate under the bottom one before securing it in place using rocks , stakes , dirt , or other means . depart the plastic - deal potting mix in full sun for 4 to 6 weeks . In area with more clouded 24-hour interval , leave it out for up to 10 weeks .
you may also place moist - but - not - wet soil into clear plastic bags , hardy mordant plastic bags , or sterile 5 - gallon bucket . right seal them off and forget the bags or bucket in the sun according to the above time passport .
For a small amount of potting soil , attempt sterilizing it in the oven by bringing it to a temperature mellow enough to obliterate off any possible pathogens . Most soilborne diseases ca n’t survive 30 minutes at 140 degree Fahrenheit . However , for a few viruses , this is n’t quite red-hot enough . It ’s more often than not agreed that broil planting media at 180 degree Fahrenheit for 30 minute of arc offers more logical success .
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To bake plant soil , spread it evenly on an oven - safe container ( like a baking pan ) , wrap up it with aluminum foil , and bake it at about 200 level for around 30 hour , using a sum thermometer to judge the temperature .
Because many people use microwaves instead of established ovens for cooking , it stands to reason that a microwave could sterilize potting soil . While that ’s technically true , this method acting is the least commend for a duo of cause : First , a planting medium can control metallic element detritus , which can damage microwave and even cause a house fire . to boot , a microwave can only accommodate a small-scale amount of potting soil at once .
Still , if this method sound correct for you , you’re able to place moist planting soil in microwave - secure containers with ventilated lids . This includes microwave - safe plastic bag , but verify they have some character of ventilation . The bag should then be place in a microwavable dish aerial to keep any dirt from shed out of the ventilating system maw . For 600 - watt and high microwave oven , microwaving on full business leader for 90 moment should do the magic trick .
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Check the stain temperature with a nub thermometer straight off afterward , repeating in 30 - second interval until the soil temperature reaches 180 stage Fahrenheit .
Once sterile, used potting mix must be amended to restore adequate structure and nutrient content for plants.
Before reusing sterilized potting admixture , it ’s of import to ensure that you rejuvenate the medium with mass of nutrients . It ’s not hard tomake your own potting soil , but the good potting soil mixes have just the ripe portmanteau of element .
Store used potting soil in clean, airtight containers.
Once potting intermixture has been sterilized and amended , keep it from attracting any new plague or pathogen by store it in an airtight container . These container should also be clean and infertile , since diseases and cuss are commonly passed from tools and container .
Our Best Advice for Beginner Gardeners
We ’ll avail you determine up your first garden — whether that ’s a few pots on your patio , a levy bed , or an in - earth secret plan out back — and pick out the right plants for your land and region .
