How to sterilise used compost for your seed and potting mixes
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- čas přidán 8. 09. 2024
- Before reusing your old or spent compost, it's a good idea to sterilise it to help prevent problems like damping off, fungal problems, kill off insect eggs like fungus gnats and aphids. It's really easy to do and can make a huge difference to the success of your seed starting and seedling growth not to mention make life easier if you have plants indoors.
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Morning ladies, I even sterilize my new compost because I’m sick of fungus gnats etc being in the new stuff too. As I use 50 50 compost and coconut coir I put the coir on top of the soil then pour boiling water on top it swells the coir and kills the critters. Thank you for sharing as always 🐝 safe ladies 🇨🇦👍
Good tip with the coir and boiling water
I'm just about to try this with the compst and coir. Thanks
Good luck
Thanks Eli for the definition page for the word beastie. I laughed out loud. Great explanation on why you sterilize your compost. Had issues with aphids one summer and did not sterilize the compost and I had a city sized population of aphids in the middle of the following growing season in my pots. Really regret the shortcut of not sterilizing. Thanks for the good video reminder.
Never again.... now you know 😀😀😀
We used to sell tshirts with Beastie on it 😀😀😀
I just came across another method that's a little faster in a video from the Louisiana State Univerisity (LSU) AgCenter on reusing potting mix, which showed how to sterilize it in a microwave. Dr Joe added enough water to make it about 50% moisture (enough so that it will feel damp and clump together but will break apart easily and not be soggy) in a big ziplock bag, leaving it open to vent, placed the bag in a large microwave safe baking dish and nuked it for 90seconds until it reaches about 200degF/93degC, increasing by 30sec intervals until it's up to temp. (Using the bag means less clean up and since it's already in a bag, it doesn't have to be transferred into one for storage.) Dr Joe said this method is scientifically proven and it would even work for dirt right out of the garden. For those of us who don't have a grill and don't want to use the oven, the micro could be taken outside. Thought I'd pass that along.
Yeah I know a lot of folk who do this, you are basically steaming it 👏👏👏
Using an outside grill is a great way to sterilize the mix without running everyone out of the house from the odor. Great tip!
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As a fungus gnat infestation survivor, I baked my purchased seed starting mix in the oven. (350 F for 25 mins) No strong smell. I like the grill idea for homemade compost! Thanks for that tip. Don't understand why steam is necessary. The heat really dehydrated the mix.
I'm a survivor too.... we had a bad one in the house.
The steam, don't stress over. Not so much essential adjustment helps. Also good to stop the compost burning if it gets too dry 😀
Good advice Eli. Enjoyed listening to you on the chat with Gardener Scott.
Glad you enjoyed it 😀
I def made the mistake to reuse old soil and now have some gnats (and a cute centipede). I think the grill is the best idea to get it done without making my family ill.
Soooo pumped to get seeds going!!!
Yay.... not long now till I can get into proper seed sowing time as well. Hurrah.
I have always just added my spent compost to my garden beds and bought new seed sowing mix. Such a good money saving and environmentally savvy idea. Thank you. I'll just have to ensure I move my seedlings on quickly. They sometimes get left in their first tray for a while longer than they should!
Oh no.... not a neglectful seed mommy????? We'll have to get you in new habits 😀
I'll have to schedule a reminder just for you 😀😀😀
Thanks Eli. I'm a potter so used an old dog bowl and my kiln to sterilise mine last week, worked a treat! This is my first time mixing my own seed compost so thanks for giving me the confidence to have a go 😁
Glad it helped! 😀
Given the cost of calor gas these days I think I will buy new compost 😊
Great information, now I know why there are bugs from my house potted plants.
They are most likely fungus gnats. They are attracted to the damp compost. There could have been eggs in compost you bought or unfortunately if we are guilty of over watering it can attract them into the house
I did this last week to make my own seed mix for the first time , so thanks very much for the advice Eli 😀 x
Awesome... you're rocking it Jim
@@eliandkate all down to you and Kate Eli lol , mix is ready to go propagators ready and list of seeds and no's all ready too , I'm waiting till 21st of February to start but I'm not 100% on that date, but we live and learn don't we x
Don't rush things.... we still have loads of time 😀
@@eliandkate yes I am impatient lol , I keep saying but I've got to learn to be more patient x
So funny I ran across your video. I actually did this for some potting soil that I was reusing but I put it on a foil lined cookie sheet in my oven at 200°F. It was a bit smelly but, I think it did the job. The reason I was watching your video is because I wasn’t sure whether I should heat up compost before using it or not. I know that my compost does not get hot enough to kill off all the weed seeds and everything else that may be in it, but I thought it might be harmful to kill off the beneficial micro organisms that were in my compost. I am planning on using it in my raised beds.
You get some funny looks putting trays of compost in the oven don't you :D
I only do this with soil I'm using for seed starting or potting mixes. If it's being used outdoors I leave it as is. Like you say, I don't want to kill anything beneficial in there. Bt there are days when I'm cursing the weed seeds from the compost bin :D
Brilliant video Eli.
Not something I’ve done before, always learning something new! Will deffo be trying this one out 👍
Now I'm surprised at that. I assumed you would be an old hand at stuff like that 😀
What a good idea with the barbecue! Great information, thank you for sharing!!!
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I just wanted to thank you for the inspiration to get me into greenhouse / raised bed growing, I have been watching your very informative superb videos for some time now and your great delivery / production makes for easy viewing....I hope that you don't mind but I call it 'brain porridge' viewing as its very absorbing and relaxing...well done to you both!
😃😃😃😃 I'm glad you explained
It's brilliant that we've inspired you, get out there and get growing and remember to let us know how you are getting on. We love hearing shout all your gardens 👍👍👍
These videos are so useful. I bought some potting compost from B&Q a few weeks ago and every tray I've started seed in sprouts these very tiny mushrooms!!! Think I'll pour boiling water on it in future and it will hopefully kill off whatever is causing it. Thanks you 🙂 🍄.
Oh that sucks
I've used boiling water before,but worried about all of the soil getting hot enough. Using an outdoor grill is a great idea!!
I do both, just depends on how much I need to work with. Heat works well for larger amounts
2lt microwave bowl with lid (ventilated) full power for 3 mins Job done
I normally do the same ... just to be sure I go for 5/6 minutes
Thank you for the video Eli, really useful for recycling compost.
Fab... glad it was helpful 😀
I used the boiling water last year. This year I will try the BBQ. Thanks for the video. Cheers 🍻
Good stuff!
Sorry, nevermind the next comment. I asked and posted my question before I had watched your whole video. Sorry. Great video!
😃 duly ignored
Fascinating idea! And such a good money saving tip. I usually buy new compost but it’s so expensive.
And not great environmentally either feeding the industrialisation of gardening and compost making, so any tiny we but we can do to reduce our reliance on buying, even a tiny but, helps us financially and helps everyone by reducing the bulk making, shipping and plastic wrapping. Do you know you can reward yourself with a wee glass if wine too 😀😀😀😀😀😀
Didn't think about using the BBQ, lol, I've always used boiling water and microwaved mine. Great idea if you have a gas one but a bit of a faff if you have a coal one like me. So excited by the way, my greenhouse will be put together on Fri so I can finally get cracking on my seed starting. 🙌🏾
oh hurrah for the greenhouse!!!!!! Can't wait to hear all about it... feel free to hashtag or tag us if you do social media. I love hearing the stories from you guys
#thekitchengardenwitheliandkate
I scorch my soil using my weed burner. Does burn some organic matter but ash is quite good for growing. Only to be done carefully outside away from anything which might catch fire.
I've used my oven as a soil sterilizer (once!) and now am thinking of moving my old microwave outside just for this purpose. It would mean doing many, many batches, but in between routine chores (goats and hens) it would just be one more little thing :)
outside would at least mean no worry of stinking out the house
Thank you so much for this video Eli. I've always wondered which way to do it. I'm further north than you so I definitely wouldn't be able to get compost dry with the kettle method!
Yeah I didn't manage to get it dry last year 🤣🤣🤣
Fab video, Eli & Kate! I probably should have mentioned I poured boiling water through mine before I dumped it in my flowerbed in my video 😂 Great video for doing a big batch! I'm glad I'm not the only person who reuses compost.
I don't understand why you wouldn't reuse it if you can 😀😀😀
You'd be surprised! I mentioned to a friend that I was going to be refreshing compost in my first video and the face she made! 😂
Old gardening myths I bet
Yeah, myths started by the compost companies 🤣
Wow you are so full of good ideas. Thankyou so much for this wonderful video!!
Glad it was helpful!😀
What a tip! Thank you
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I just used your boiling water method on some spent potting mix from houseplants, and "hacked" my way out of the sogginess issue with coconut coir: after the old mix was properly soaked in and sat in the boiling water for a half hour, I added some crumbly bits from the side of a big brick of coco coir, and it absorbed all the extra liquid super quickly. With a bit of mixing it was nice and fluffy and moist, I was able to pop seeds in right away (winter density lettuce, sown indoors with lights and a heatpad, but I couldn't wait to start *something* lol)
Oh total genius hack
I can tell you winter density are fab for sandwiches and things 😂
Never done this before but I should definitely try this with my cuttings! I have a lot die since I just leave them outside. (Concerned about beasties in the house) but I think I would have better success if i bring them inside
outside maybe isn't best for certain things, but there's a lot more to cuttings than just the compost. Could maybe be as simple as not enough moisture etc?
Hi Ladies,
Interesting discussion this one. I am sorry, I will be a bit controversial - although I am still quite new to growing. I can fully understand why you want to sterilise your seedling mix: seeds don’t need nutrition to germinate, just a growing medium.
But by sterilising your compost you be killing the nasties but also the life that is in the compost. Yes, minerals will survive but compost (soil) is a living organism, and a lot of goodness will die. Spent compost still has loads of goodness to be had.
Not controversial at all 😀, maybe a misunderstanding in that this is for seed starting, so something you use as a very temporary environment. It doesn't need to have any beneficial soil life at all. It's only purpose is to hold moisture and provide stability. The seedlings will be in it for a few weeks max before getting moved on.
Seed starting mix and a lot of potting mix is soiless, so is never designed to have the natural soil life you'd expect in say a garden bed or outdoor containers even.
I use boiling water and on seedlings,vermiculite on top,helps keep mould & fungus at bay
Wish I new this a month ago thanks for the info
So just how much spent compost are you guys hording ready to go??
love this idea thank you
Thanks Eli
You're welcome 😀
tried to grow strawberries from a strawberry before and out of 30 seedlings i have one left. i think fungus nats was the culprit,but had never seen them before. since then i use boiling water and never had the problem since..
Hurrah
I have sterilised mine on occasion using boiling water. Never the oven though, I bit concerned about doing it this year though cos ummm theres loads of wormies and I don't want to hurt them or their babies xox
Ha ha ha
Another brilliant video. Was wondering how steralise large amounts. And using the bbq so you don't get the smell indoors. Thank you Eli 😊
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Hi Eli, great video, never thought of sterilising my compost, thanks for sharing & take care 🙂
Good luck 😀
Great tips👍
Glad you think so!
Sterilizing also kills off bugs and their eggs.
You are always on top of things. I don’t know where you get the time for all this. I’ve not tried this before….but will. Do you think this process would kill any weed seeds that might currently be viable in homemade compost?
It should do yeah
Great idea about using your BBQ!
Keeps me on good terms with the wife
Hi Eli
I absolutely love all of your videos. I have been gardening for decades and started following you at the start of the first pandemic in 2020. I have learnt so much from you. I wanted to know if I could sterilise soil from pots which had tomatoes that got late blight last year. I cleared away the infected plants and emptied the soil into 2 large dustbins. Can the sterilised soil be used for seed sowing or is it better to go on the flower borders?
Thanks
Minni
I've never had blight so it's not an experience I can tell you about but I've been told by others that tomato blight yes... potato night no. 😀
Have u tried chamomile tea on seedling that works well with killing bugs 🐛
How does that work? How does I kill bugs, what bugs and how do you use it?
@@eliandkate just make the tea up and put it in spray bottle and spray the plants. If u want more information check out Geoff foreman on you tube
You don't have a link to the study about this do you? I'm being lazy hoping it'll save me going and finding it
@@eliandkate czcams.com/video/WiT7MNDCPHM/video.html
This is the video, where its mentioned.
czcams.com/video/WiT7MNDCPHM/video.html
Hope this helps. I found it helped my seedling last year
Interesting video and relevant 🙂🙂👌👌
Good to hear
Wooooooow!!!
🤣🤣🤣🤣🤣🤣🤣 really???
Really useful video. Do I sound like a sap when I say that I don’t like sterilising spend compost in case I frazzle some insects or worms 🙄. I take the hit and buy fresh. I have a cheek when I encourage my chickens to have a good root around to find tasty beasties to eat. 😙😙😙
Ha ha ha are you braces for the lecture on the enviromental cost (to all if us including the beasties) of buying compost???
This is a great way to reuse. Can you tell me if this destroys vine weevil grubs/eggs?
It should do Joe
I have a Vego and a Birdies raised bed. I have a 3rd bed that is either a Vego or a Birdies also. Anyway, I want to use my compost that I made in a compost tumbler to add to the soil mix that I'll use to fill the 2 that I have yet to get put together and fill up.
Since I had gradually made the compost, adding things over time, my compost was a pretty much "cold process" vs me adding a bunch of material at once, and having it "cook" in the barrel. So, I'm worried about seeds from the plants I had added to my compost barrel. So, I want to sterilze the compost before I add it to the mix that I will fill the raised beds with. But, what I want to know is will the sterilization process kill the "good stuff" that's in the compost? Or is the temp that is used to sterilize it too low to kill the "good stuff?"
Compost gets hot when you add greens to it, so, maybe it's okay to sterilize it when it comes to beneficial organisms?
Hi, firstly great video. I did the boiling water method on a small amount of compost before and it seemed to work. I've read through all the comments, I can see why you would do this for seed starting mix (regardless if you're using bought or spent compost). I did get a little confused on one of the comments about nutrition, so wanted to clarify.
Would you use this method before using in house plant potting mixes? Or has it then lost its nutritional value?
Is this process useful on spent compost which is going to be reused in flower or veg beds? Or is it that unnecessary?
I'm very keen on reusing - throwing away compost/soil just doesnt seem right to me. I also have ME, so I need to be clever with how I use my energy. Though at the same time, I'd much rather take the time to get it right at the beginning to avoid pests etc.
So you could use this on potting mixes yeah, although I can’t comment on proper organic as without knowing what the nutritional element is you can’t say what boiling water would do, but yeah I use it for all my seed mix and potting mix if it’s for indoor plants and I don’t want to bring bugs indoors.
You can do this with heat too which might be a little bit less of an energy spend for you?
Hey Eli, I’ve heard of solarizing soil where you lay out soil on a tarp in a sunny location then place clear plastic over top (I’m thinking a cheap clear shower liner) then leave in the sun for a few days or however long it takes to get it to desired temp to kill off everything… I don’t recall how long, sorry ..but then the sun bakes it for you. Would that ruin the soil too much or remove too many of the good microbes and nutrients? Thanks for sharing all your great ideas and helping me get smart(er) ; )
Hey Adrian
Not something I can do…. We don’t get sun like that, but I have heard of it.
When you are sterilising compost for seed starting mixes you aren’t bothered about nutrients and a seed mix doesn’t need them.
The plants are in seed starting mix for a really short time just till they get going 😊
Hi Eli. I grew some potatoes and sweet pea flowers in pots last year....i was going to dump the remaining soil on top of my flower beds in the garden....would you advise against this? Dave from Ireland.
absolutely not, I do this loads too. Talking about sterilising used compost is simply part of the process for making my seed mixes. That's a whole different thing because we are talking about seed starting and seedlings which can be very delicate and susceptible to fungus etc
@@eliandkate That's great Eli. Thanks a million.
Nice one Eli 👍
Would this method also kill off weed seeds?
I get a lot of it growing through! 😖
If you get it hot enough it can, yeah
would microwaving work?
Yup. Loads of folk microwave if they are only doing small batches
I have microwaved mine on occasion.
What about the worms that are good for compost?
hey Rachel,
don't worry, this video is part of the seed starting series. So I'm only talking about the used compost from your pots etc and only in relation to making seed starting mix. This isn't general advice for all compost use. 😀. I actually use a lot of used compost out in the garden, just chuck it straight out there onto flower beds etc. No need to sterilise it or do anything with it. I'm only talking about sterilising used compost if you are reusing it as part of your seed mixes and are worried about the chance of passing on unwanted pests or fungus to delicate and susceptible seedlings 😀
If you have lovely compost or worm castings I wouldn't waste that on seed starting 😀
@@eliandkateto clarify, do you mean that when we are putting compost on a garden bed at the first of the season out of our hot bin or cold compost or something we shouldn't stareilize it? I was thinking it might be a good idea in case something didn't get killed in it. I also have a hot bin like I think I saw you have and it gets 40° c (in the green zone) but it still makes me worried that something might have survived 😅😅
No there’s absolutely no point or need to sterilise compost for the garden.
After all, you WANT all those organism in your soil.
We only sterilise seed starting stuff to try to get the best results… by reducing the chance of damping off or getting fungus gnats in the house/greenhouse
👍
What are you sowing now?
Nothing yet but will be the next few tomatoes in a bit 😀
Hi, Do i need to sterilise seed compost, or only sterilise multi purpose?
Hey Lynda
OK 2 things then. If you use multipurpose compost, you might want to sieve it to get it nice and fine.
You don't NEED to sterilise any compost but it's one of those things you can do to help reduce the chance of nasties killing your seedlings
Hiya Lynda. I think Eli [like me] uses some spent compost in the seedling mix which she makes herself. It is only the spent compost that needs sterilising, really.
Hey I was trying to find the link to the video where you talked about how to dry out a small amount of compost. Could you help me with that? I can't figure out how to do it without baking it
Em
I’ve not done a video on drying out compost
I’ve done a few with different ways of sterilising it, is that what you mean?
Yeah! In one of your videos, maybe this one you mentioned sterilizing compost and then drying it out if it was a small batch and then you talked about sterilizing it in the oven but I couldn't find how to dry it out except for in the oven@@eliandkate
@HallidayBrittany ok I have one about sterilising a small batch, I don’t have any about drying it out
From a few weeks ago
czcams.com/video/FlkNG9C1Jlo/video.htmlsi=gAvoC-QI6WhWTsnJ
I didn't know this was a thing 😅
There you go… you learned something new
Dear Eli and Kate, okay - so I reckon you will be horrified, but some people (naming no names) microwave theirs. . .
🤣😂🤣😂🤣 oh there are quite a few there.
I microwave mine - quicker and cheaper!
Christ how many loads do you have to do to get it all microwaved 🤣🤣🤣🤣
@@eliandkate LOL - I just do each batch as it is needed. Maybe a kilogram at a time I guess. Fresh as a daisy then.
I had visions I your other half going crazy at you 🤣🤣🤣🤣
@@eliandkate PMSL - I'm lucky, I am both halves 🤣🤣 but I have to say some of my meals are a bit gritty 🤣🤣
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