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Is wood ash good for the garden soil? Our favorite college horticulture professor, Debbie Flower, answers decisively with, “it depends”. She has tips to help you decide if your soil will benefit from the addition of wood ash. She also tackles the topic of ash from nearby wildfires falling on your garden. Good or bad?
And we talk with Organic Gardening expert Steve Zien about how you can achieve better soil starting this time of year, with a lot less work. His tips might even allow you to skip the tedious chore of crop rotation each year!
It’s all on episode 144 of the Garden Basics with Farmer Fred podcast, brought to you today by Smart Pots.
And we will do it all in under 30 minutes. Let’s go!
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Garden Basics 144: Using Ash in Your Garden. Better Soil with Less Work
22:40
Farmer Fred 0:00
Garden Basics with Farmer Fred is brought to you by Smart Pots, the original lightweight, long lasting fabric plant container. it's made in the USA. Visit SmartPots.com slash Fred for more information and a special discount, that's SmartPots.com/Fred. Welcome to the Garden Basics with Farmer Fred podcast. If you're just a beginning gardener or you want good gardening information, you've come to the right spot.
Farmer Fred 0:32
Is wood ash good for the garden soil? Our favorite college horticulture Professor (retired) Debbie Flower answers decisively with... "Well, it depends." She has tips to help you decide if your soil will benefit from the addition of wood ash, and she also tackles the topic of ash from nearby wildfires that might be falling on your garden: Is it good or bad? And we talk with organic gardening expert Steve Zien about how you can achieve better soil starting this time of year with a lot less work. His tips might even allow you to skip the tedious chore of crop rotation each year. It's all on Episode 144 of the Garden Basics with Farmer Fred podcast, brought to you today by Smart Pots. And we'll do it all in under 30 minutes. Let's go.
Farmer Fred 1:23
We like to answer your garden questions here on the Garden Basics podcast. I say, "we", because joining me here today, our favorite retired college horticultural Professor, Debbie Flower is here.
Debbie Flower 1:33
Yes, I am.
Farmer Fred 1:35
You know, especially during the wintertime and the colder times of the year, a lot of people like to take the ashes out of their wood stove or fireplace and scatter them throughout the yard. And there must be some reason why that would be good for a garden. I'm not sure what. But a question came in to the Get Growing with Farmer Fred Facebook page from CW who asks about wildfire, smoke and gardens. And she heard that a certain amount of ashes are good for gardening. Because here, especially here in California and Oregon, where wildfires are prevalent this time of year, it seems to be on too regular of a basis, there's usually ash that goes along with the smoke, you can usually see it piling up on the car, right? I think we've talked in the past about ashes, landing on plants and cutting down photosynthesis, right?
Debbie Flower 2:28
By creating shade and not allowing enough light, right. Or as much light into that plant part.
Farmer Fred 2:33
But what about adding ashes to a garden soil?
Debbie Flower 2:36
That can be done, and it can have some benefit. Ash from wood, like you talked about in the beginning about out of the wood stove, where you've burned, just logs, nothing chemical, just logs, do have some nutrients in them. About 20% of the content of the ashes can be or up to 20% can be calcium, which is needed for cell wall development, about 5% is potassium, that would be the third number on a fertilizer bag. And then you can have up to 2% of magnesium, phosphorus and or sulfur it's going to depend on what went in. Good wood in, good ash out. And then that can be applied to the garden, but at a very low rate. And that would be about one pound per 100 square feet. And the reason for that is that the other thing that ash can do is change the pH of the soil. Generally it raises the pH if you have a soil test done and your pH which is a level of alkalinity versus acidity, is good for gardening. Applying ash may not be right for you because it would change the pH and a different pH changes the availability of nutrients to the plant.
Farmer Fred 3:52
Exactly. That is one of my favorite illustrations in my brain of the benefits of the proper pH with the plants you are growing. Some plants like an acidic pH, some like a neutral, some prefer alkaline. But think of it as tubing in the soil that's feeding your plants. It's like plant food that's going straight to your roots via a tube. Okay, and it's the size of the tube that determines how much food gets to your plant. If the pH is wrong, it can be a very narrow tube so your plants aren't getting the nutrients it needs. If it's at the ideal pH then that pipeline will be at its maximum diameter and more food can go through. Now that is a very simplistic demonstration of pH but it frankly if it's the wrong pH it does retard nutrients.
Debbie Flower 4:46
Right. But it's a good example or a good analogy because the nutrients are still there, it's just that they can't get the plant can't get them. It's not that they've somehow moved out of the soil but they've become unavailable to the plant.
Farmer Fred 5:01
And that takes us on another scenic bypass. Yes, I don't know if I want to go on this bypass or not. But all right, I will, just for the heck of it. Citrus trees and acid loving plants that have yellowing leaves are said to be chlorotic. And it's usually a very specific yellowing of the leaf, it's usually a yellow leaf with green veins. Yes. And if you go to a nursery or a big box store and you're telling people about this plant problem, they may say, "Well, your plant needs is iron. So here, buy this bag of iron stuff and put it around your plants." When in reality, it could be that the pH of your soil around that acid loving plant is too alkaline, right? And so it's just a matter of readjusting the pH to open up because your soil probably has enough iron, the only way to know is to get a soil test. Yes. And that would be the first step really, is to get a soil test done. But the fact of the matter is, if you have the right pH, a lot of things will go right. Yes. In the garden. Yes.
Debbie Flower 6:02
So the iron may be what the plant doesn't have in its tissue, but it may be available in the soil. It's just that the plant can't get it.
Farmer Fred 6:10
All right. If you have acid loving plants, and you are putting down ash in your garden that can really muck up matters, yes?
Debbie Flower 6:18
You can end up having that symptom you just talked about, which is yellow leaves with green veins.
Farmer Fred 6:23
And you can put all the iron you want on there, it's still not going to be able to get to the plant because the tube is clogged. Right. So to lower the pH of the soil, you would add something like sulfur, yes, that's a very slow reacting substance. This is something you would do months ahead of time.
Debbie Flower 6:41
Yes, you do it in the fall to get results by spring, right.
Farmer Fred 6:44
Blueberries, for example, are an acid loving plant, they prefer a pH around 5.5, which is fairly low, very low. Yeah. And this time of the year, fall would be the time of year to apply sulfur. If that soil test you had done around your blueberries showed that it was getting a little bit too alkaline, maybe doesn't even have to be up at alkaline levels, just getting there it could be in the mid sixes. But as soon as it gets over seven, then it's starting to get to alkaline. So you might want to consider sulfur to lower the pH. I guess if you want to raise the pH you could add ash.
Debbie Flower 7:20
Yes, and please, people, who live in very wet places, this is a very general comment. So don't assume you know your soil pH based on what I'm going to say. But places that get a lot of rain. I've lived in the in New York and New Jersey and the Portland Oregon area, which got over 40 inches of rain a year. In places like that the soil is naturally more acidic because of the action of water on the organic matter in the soil and what washes through in places that are drier like Tucson, Arizona, Central Valley of California, Eastern Oregon, places like that, that have very long dry periods that the soil tends to be alkaline have a high pH. Acidic is a low pH below seven. Alkaline is a high pH above seven. So if you live in a place that gets lots and lots of rain, if you're in the Olympic Peninsula of Washington which can get over 100 inches of rain a year, then ash to your garden, you may do all the time and it may be fine. But if you live in a place that's dry like Tucson, Arizona ash in your garden could be the death knell to your plants.
Farmer Fred 8:28
Alright, so take that into consideration. So basically if you're going to put ash in your garden, do so very judiciously.
Debbie Flower 8:35
Right, and have at least the pH of your soil tested regularly.
Farmer Fred 8:39
And you can find those test kits at nurseries everywhere,
Debbie Flower 8:43
You can buy the test papers, the strips, or you can buy the chemicals. If you have kids, the chemicals and you shake them and they change color and you compare colors. That's always fun to do with students.
Farmer Fred 8:52
There you go turn your kitchen sink into a lab. Yeah. All right. It's one thing to have woodstove ash, but wildfire smoke ash, who knows where that came from.
Debbie Flower 9:02
Think about all the stuff in your house. A lot of the part of California that is burning, or has burned in the past is forest, but there are also structures in there: houses, businesses, barns, think of the things in your house and if they burned, what are they made of. Whatever they're made of is going to be in that ash and in that smoke. And that can contain a lot of nasty stuff. Heavy metals, for instance, things you absolutely do not want in your food.
Farmer Fred 9:27
And that also includes PVC pipes as well, right? That was a big problem up after the Paradise fire, people could not use their own water supplies until they had thoroughly checked all the PVC pipelines carrying water to these households to make sure that there was nothing in there In the way of contaminants.
Debbie Flower 9:48
Because they're made of plastic and plastic is made of oil and oil is not something we want to garden with, or drink. If your property has not burned, I don't think the quantity of ash you're going to receive will damage your plants. But if your property is burned or for some reason collecting ash from a burned property, that would be when it's dangerous.
Farmer Fred 10:10
That would be if you're moving back into a burned out area you might want to do raised bed gardening.
Debbie Flower 10:16
Yes. Use a Smart Pot.
Farmer Fred 10:19
Yeah, good idea. Well, we learned a lot about ashes today, Debbie Flower. Thanks for the good info.
Debbie Flower 10:25
It's a pleasure Fred.
Farmer Fred 10:29
Smart Pots. It's the original award winning fabric planter. It's sold worldwide and Smart Pots are proudly made 100% in the USA. Smart Pots, by the way, are BPA-free with no risk of chemicals leaching into your soil, your herbs, vegetables and other animals. That's why organic growers prefer Smart Pots. And they last for years. Some gardeners have been using the same Smart Pots for over a decade. Smart Pots breathable fabric creates a healthy root structure for plants. Because the fabric breathes, Smart Pots are better suited than plastic pots, especially for really hot and really cold climates. And unlike a plastic pot, the fabric won't crack or break from frost or when dropped. For more information, visit SmartPots.com/Fred. And don't forget that "slash Fred" part, because on that page are details of discounts when you buy Smart Pots at Amazon. Visit SmartPots.com/Fred.
Farmer Fred 11:33
Well, we're going from summer gardening to cool season gardening and maybe you don't want to put in cool season crops. Maybe you don't want to deal with plants that might be killed by a frost or freeze. But don't leave your summer garden intact. In its place, there are some cheap and easy things you can do that will not only minimize pest problems for the following years, but also during the winter, feed your soil and make it even better for next year. We're talking with Steve Zien. He is Sacramento's organic advocate. An organic gardener for decades. He ran his own organic gardening and consulting company for decades. And Steve, I know we've talked about cover crops before, but going beyond cover crops. If people want an easy way to feed their soil during the winter, and they don't want to grow cool season crops... I think one of the easiest things to do, well two things to do, is a cut down everything to soil level. If you're growing tomatoes and peppers, just cut them off at the soil level, but leave the roots in the soil and then cover that soil with leaves that are falling from the trees in the fall, grind them up with your mower or a weed whacker or something and just put down six-eight - twelve inches of leaves on top of that garden bed.
Steve Zien 12:56
Yeah, it's absolutely wonderful. It regulates the soil temperature, the soil temperature will be warmer. The fact that it's all ground up makes it easier for the biology that's in the soil to come up into that mulch and munch it down. And then the rains will help leach those small little particles down. The worms that are in your soil will come up and feed on that every single day. And you know if it's a thick mulch, even at night, because it'll be dark and they will be aerating your soil and and taking that organic matter of material down into the soil. And the nutrients that leach through by the rains will also leach the biology because that'll start composting on the top of the soil and the biology that's compost then will increase in numbers and will end up moving down into the soil as well. So you will get nutrients move down into the soil and increase the nutrient value and you will get more soil biology. And the more soil biology you have, the more diversity, the more numbers, the healthier your soil is and the healthier your crops will be. I just took a class recently, everybody has been talking about rotating your crops for decades to reduce pest problems. And they're saying that if you have the right biology and you put down you know, you either grow cover crops or you put down a thick mulch, you really will have the biology in there, the beneficial soil biology to naturally combat the pest problems and you should not have to rotate your crops.
Farmer Fred 14:49
I love it when you're a contrarian. And, it makes perfect sense, too.
Steve Zien 14:54
Yeah, if you've got the good soil biology down there. And then you're feeding it with either a cover crop or with a thick mulch, you're feeding though that good biology. And so the good biology will fight it out basically with the bad biology and not allowing them to grow in substantial numbers, where they could do harm to your plants the following season.
Farmer Fred 15:22
Now I mentioned earlier about clipping off the tops of the plants and leaving the roots in place, true or false.
Steve Zien 15:31
True. Because they will decompose and typically will decompose pretty fastly. Again, that's if you have an organic, happy, healthy soil. If you've been using pesticides, you've been using synthetic fertilizers, the biology isn't going to be there to break that stuff down. But if you are growing organically, you'll have a lot of biology in your soil that stuff most of those roots will break down very very quickly. And they will create air channels there and they will end up aerating your soil. Because where the root was, there's nothing there anymore. And so you've got these big pore spaces. So when you irrigate next spring, the water's gonna move in through the soil, the worms can move through the soil better, the soil biology can, you know, all of the various you know, microbes and beneficial mites and protozoa and all those guys can move through the soil and do their job better.
Farmer Fred 16:29
And you're also improving water percolation for the years ahead by keeping those roots in.
Steve Zien 16:35
Exactly. Because they will decompose. The biology will basically reduce them to nothing. And there will be large, large pore spaces where those roots were and so when you irrigate, the water will go down very, very nicely, which is important. If you've got a clay soil, and at least here in the Sacramento region, most gardeners have a clay soil.
Farmer Fred 16:58
I think across the country, there are a lot of gardeners who are dealing with clay soil. Yes. You mentioned a very unusual word here. I'm not sure what it is. You're talking about to help that mulch layer on top break down, that "rain" could do that. What is this thing called "rain" that you're talking?
Steve Zien 17:17
I don't know. It's been a long time. And you know, in the last year we got what, seven inches, something like that.
Farmer Fred 17:26
Yeah. Now that brings up a question if it doesn't rain. Man, I hope it rains, but if it doesn't, this fall and winter here in California and in many areas of the West, if you don't get the fall and the winter rain, should you irrigate the top of that mulch, like once a week? Just turn on a hose and start sprinkling it?
Steve Zien 17:47
I think it would be a good idea once in a while. Certainly, once a week it's not necessary. Typically, if you do it once in the wintertime, it's not very hot. In many cases, it will hopefully be cloudy. Make sure that mulch is moist, not wet, but moist when you put it down or after you put it down. And then, before you add more moisture, don't just look at the surface, dig down an inch or two and see if it's dry. And if it's dry, then you might want to add more more water.
Farmer Fred 18:26
Alright, it's a good point. And to reinforce something we said earlier: the smaller the pieces of those leaves that you're using as mulch, the better the quicker we can break down and feed the soil. And plus, if you're just stacking 12 inches of unchopped leaves on top of your garden bed, you might create an anaerobic environment.
Steve Zien 18:46
It would help to grind it up some way. And you know a lawnmower works well. And you mentioned that another easy way to do it if you've got a string trimmer is get like a five gallon or get a garbage can and put a small amount of the the mulch in the garbage can and then run your weed eater down in there and it'll chop it up pretty nicely as well. It's an alternative way to do it.
Farmer Fred 19:13
And to save wear and tear on that garbage can make sure it's a metal garbage can, which are still available. They're out there. Yeah, usually a 27 or 32 gallon metal garbage can and then put those whole leaves in, like you said, maybe fill up that can 1/3 and then put your string trimmer in and turn it on, whirl it around a while and you'd be surprised at how the level of leaves drops. And then you can pile more in there and then chop it up again and just do it in increments like that.
Steve Zien 19:42
Yeah. And make sure you have a string trimmer. I know on some string trimmers, you can put like metal blades on them. That's gonna pretty much destroy your container.
Farmer Fred 19:56
Yeah, and wear eye protection anytime you do that. And string trimmers, not even the plastic blades. The string trimmer is best. Yes. If you're not going to be planting cool season crops this year, then the least you can do for your soil is cover it with mulch, chopped up leaves is great. Just leave it on til spring and you don't even have to remove it in spring. You can just move it aside and plant whatever you're going to put in come springtime and keep that as a permanent mulching area. Just make room for your plants.
Steve Zien 20:32
Exactly.
Farmer Fred 20:33
Mr. Exactly is with us. Steve Zien, Sacramento's organic advocate, of Living Resources Company. Steve, thanks for the good cool season advice.
Steve Zien 20:41
It's been a pleasure as always, Fred.
Farmer Fred 20:52
The Garden Basics with Farmer Fred podcast has a lot of information posted at each episode: transcripts, links to any products or books mentioned during the show. Plus, you can listen to just the portions of the show that interest you, it’s been divided into easily accessible chapters. There’s other helpful links for even more information, including the new Garden Basics newsletter. And just like the podcast, it’s free. Plus you’ll find more information about how to get in touch with us. Leave an audio question without making a phone call via Speakpipe, at speak pipe dot com slash gardenbasics. it’s easy, give it a try. And you just might hear your voice on the Garden Basics podcast! You can also use your phone to call or Text us the question and pictures, 916-292-8964.916-292-8964. E-mail: fred@farmerfred.com . If you tell us where you’re from, that will help us greatly to accurately answer your garden questions. Because all gardening is local. In the show notes you’ll find links to all our social media outlets, including facebook, instagram, twitter, and youtube. Also, there’s a link to the farmerfred.com website. And if you would please, if you hear something you like, share it with your friends and family. Thank you!
Farmer Fred 22:17
Garden Basics comes out every Tuesday and Friday. It's brought to you by Smart Pots. Garden Basics is available wherever podcasts are handed out. And that includes Apple, Iheart, Stitcher, Spotify, Overcast, Google, Podcast Addict, Cast Box, and Pocket Casts. Thank you for listening, subscribing and leaving comments. We appreciate it.
