How To Build A Keyhole Garden with Cristina da Silva

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Cristina da SilvaCristina da Silva is a passionate gardener from Toronto Canada.  She has over 30 years of practical experience as a horticulturist, garden writer, nature lover, and journalist.  Cristina penned the condo gardener column for the Toronto Star newspaper and now hosts the hugely popular #GROUNDCHAT every Friday at 2pm on Twitter.

Cristina freely shares her gardening tips and wisdom and documents what she has created in her own personal garden this season.

In This Episode You Will Discover:

  • how to build your own “Gabian Basket” in your backyard garden
  • tips to create a “Keyhole Garden” to retain moisture and create self-nutrienting soil
  • how to properly test soil to see if its phytotoxic!
  • 3 tips to properly start your own patio container garden


  • Attention Garden Lovers! Do you want to save time, save money and have your most amazing garden ever?  Receive free tips, strategies and gardening techniques from passionate gardeners from around the world.  Join the VIP Club for FREE today at
  • How healthy are you really? Take the test at


Mother Nature Network – 15 Handy Online Tools for Gardeners

Ramon Gonzalez – Mr. Brown Thumb

Handy Helen – Helen’s Blog

This is the book Cristina mentioned on the show!

Interview Links

Follow Cristina on Twitter: @cristinagardens

Cristina da Silva’s Blog:

Free Report Reveals.. The 5 (Dirt Cheap) Tools I Use To Grow 22 Types Of Heirloom Tomatoes (Including My Secret Soil Booster)  Click Here To Read


Watch the Podcast Interview here:



Interview Transcript:

Dave:  Well good morning, good afternoon or good evening depending on where you are in the world when you listen to this.  And the fact that you can hear my voice means I remembered to hit record this time.  I’m Dave Ledoux and welcome to another fun edition of Back To My Garden.  Today if you’re driving or jogging and listening with your earbuds you’re going to want to take notes because we’re very excited to have somebody from my part of the world in a relatively similar climate.  She has a background in horticulture.  She’s a horticulturalist.  She’s a garden writer.  She used to write the Condo Garden column in the Toronto Star back when newspapers were a thing.  Now you can find her on the internet in a big way.  She has a background in martial arts, we may explore that today.  She’s a nature lover, more than 30 years of experience in gardening.  And she’s also the host of #Groundchat on Twitter every Friday at 2 o’clock eastern.  We’ll definitely talk about that today.  Please welcome to the show, Cristina da Silva, welcome Cristina!

Cristina:  Thank you Dave it’s nice to be here and thank you for inviting me.

Dave:  Now people are listening in cyberspace all over the world, but you’re actually about two and a half hours from me in the big city of Toronto, Canada.  I want to get to know you a little bit and I know my listeners want to hear your story.  Can you just take a minute and share with us a little bit about your background?

Cristina:  Ok.  I discovered gardening about 7 years old.  I used to live in Blentime, Malawi in Africa.  And we had about a half an acre all in garden so I grew up around gardens.  It’s always been a constant with me.  One of the biggest challenges when I was growing up as a student is that I didn’t have the land and because I grew up with land I just assumed that you had to have land if you wanted to garden.  Fortunately I discovered container gardening just in the nick of time, and since then I’ve been container gardening and also in-ground gardening as I call it.  So that was one of the biggest ah-ha moments when I realized it doesn’t matter where you live, if you want to garden you will find a way.

Dave:  So you started off in Africa and now you’re in the big city of Toronto.

toronto cn tower

Cristina:  Actually I live in Brampton, so it’s more suburban than city living.

Dave:  Lovely.  When you said container gardens a big cheer went up from our listeners because we have a lot of container gardeners.  Talk to me a little bit about your struggles.  I know you’ve been gardening a very long time.  Can you remember what it was like when you started gardening as an adult?  That transition from working and then “I’m going to grow something”?

Cristina:  Well it was never a struggle to me, once I discovered the container gardening I just started doing it.  I think I have a green thumb!  Not only do my parents garden, my grandparents garden and their parents before them.  It seems to be something that is sort of innate so I was a little surprised when people struggled with it.  And I know they do because I’ve met them.  But I think when it comes right down to it, it depends on the kind of soil you use.  Even in pots it’s really important to pick the right potting soil and you can’t cut corners there.  If you’re going to spend any money make sure that you spend it on good soil.  It seems really unsexy but it makes all the difference in the world.  Between a skinny tomato standing in the windowsill and having a nice lush one that’s growing very well.  And oh yes, and the size of containers!  It always surprises me that people think they can grow a lovely big thing in an 8 inch pot.  But I fell into this as well.  I started in smaller containers and then discovered that bigger containers do so much better.

Dave:  I told you that you’d get some pearls of wisdom today folks!  I think a lot of people struggle with the size of their containers.  It’s got to be a human thing.  I wanted you to talk more about soil.  We have a saying that “you are what you eat”.  Does the same apply to plants?

Cristina:  Absolutely!  There is a big movement nowadays about growing nutrient-dense vegetables.  A lot of it has to do with adding minerals back into your soil.  Some soils tend to be mineral deficient.  In my mind it’s not just that, if you’re growing nutrients it is important that the soil is good, but it’s not just about the minerals.  You need the minerals and you need plenty of organic matter in the soil as well.  Whether it be a potting soil or a in-ground soil.  Of course potting soil is almost all organic matter so you don’t have to worry about that.  And the other thing that I always emphasize especially if it’s something that you’re going to eat is using organic fertilizers because that way you’re feeding the soil which then feeds your plants which then feeds you.  A commonly used adage is “healthy soils equals healthy plants which equals healthy people”.

Dave:  Brilliant!  I know you write a lot about this on your blog.  Let me drop your blog, make sure you write this down if you’re not near a computer everybody.  It’s  I’ll put a link in the  as well.  Cristina you’re talking about soil.  Do you see new people trying to cut corners when they’re gardening and is that one of the places they make the mistake of cutting corners?

Cristina:  Yes, you’re right.  Out of sight, out of mind.  But it is all good gardens, and I mean this, start with good soil.   You can’t cut corners when it comes to the soil.  And I’ve seen many people go out and just buy soil in the bags.  The $2.99 ones.  And you’re not guaranteed what you have in those bags because there are no regulations for those.  So they can put anything and they can get away with it.  So people just tend to buy it, it looks dark, yes that’s soil, but they’ll find a lot of times things won’t grow in it.  A good way of finding out if that soil works or not is take some of it, a small amount of it, and grow some tomatoes or some marigolds on it, start if from seed.  If it germinates and grows to the second leaf then you know at least it can germinate and grow.  It can germinate and then you grow it for a little while longer, about two weeks longer after that, then you know not only can it germinate in it, but it can also grow in that soil.  A lot of the soil you will find may not do that.  It depends also what kind of woody material they’re putting in it.  Some of that woody material is phytotoxic.  That means that it’s harmful to plants, plants won’t be able to grow well in it.  And I don’t think that a lot of people realize that.  I remember feeling quite shocked to find out that there aren’t any regulations on topsoil.  There are regulations on potting soil because about a decade ago there was a big kerfuffle about, I think it was some contaminates in potting soil, and ever since and then legislation came in and now there is regulation and legislation around potting soil.  But not top soil.

watering can soil

Dave:  Wow.  I mean so many rookie gardeners just head down to the big box store, you pick up a couple of bags for $2 or $3.  And it’s no wonder there’s weird weeds that don’t grow from around here, I’m speaking from experience of course.  You’re almost saying take it for a test drive, like audition it, make it qualify itself before you put it work by growing some test pots.

Cristina:  Yes, I know that’s extra work that when you’re a beginner just seems like another obstacle.  So I would say if you’re starting off the best thing to do is get the best that you can get.  Ask questions.  If you’re going for topsoil where did the topsoil come from?  What’s in it?  Maybe they have soil tests.  If they’re a reputable company they should have some soil tests on it.  The “yellow bag” for example does.  You know that one you can buy?  In those big square bales?  They’ve tested the soil so you know what you’re getting.  I’ve actually used that and things grow very well in it, almost too well.  And they didn’t have any weed seeds.  And that’s the other myth.  If you think you’re going to get a top soil without any weed seeds it’s almost impossible to get something without weed seeds.  So just realize that even if it’s the top, top quality there might be a few weed seeds so don’t be too disappointed.  It’s next to impossible to get rid of all of them.

Dave:  You’re sharing with tremendous authority, I mean you have 3 decades of gardening experience.  But I’d like to take you back Cristina perhaps when you were just starting out.  Can you share with us maybe a humorous story where you had a catastrophic failure in your garden, or you did something so wrong you can look back at it and smile?

Cristina:  Oh yes!  I remember I was 7 years old, this was when I first started gardening.  I asked my mom “could I have a piece of land so I can grow something?”  So she gave me this really rocky sandy soil right on top of this rock and I was very fortunate.  I actually grew beans on it.  And it did very well, as you know beans work.  So my mom saw this and she thought “I could use that land for something I want to grow” so she traded me for another piece of land under a peach tree that had cedar bushes around it.  Now at that time I didn’t realize that the dense shade and the heavy roots would cause nothing to grow.  So I tried everything and nothing grew.  I learned that soil as well as shade as well as the type of plants growing next to you are very important.  I learnt that really early on.

Dave:  Fantastic!  Growing in the dead zone under the umbrella.

Cristina:  Exactly.  And I’ve actually seen those a couple of years ago I was going through a garden tour and someone very proudly showed me that they had started a new vegetable garden under the shade of their trees.  And I thought “Oh this brings back memories!” .  I didn’t have the heart to tell her in front of all the people that she chose the wrong spot.

Dave:  I guess that’s the experience, right?  Learning what grows next to what, learning about seasons and zones.  In the old days you had to go either to a library and rent the book or study under somebody who was experienced.  Now with the internet there’s so many resources.

Cristina:  I love the internet!  In fact I did a little search yesterday and found something that could take you from A to Z without any problem.  It covers  everything.  One of my garden writer friends wrote a wonderful collection of online gardening tools for the beginner gardener.  And it’s on Mother Nature network.  Let’s see, it’s called The Fifteen Handy Online Tools For Gardeners, so if you put that in Google and look up Ramon Gonzalez that wrote it.  And you might know him as Mr. Brown Thumb on Twitter.  He put together fifteen fantastic tools that takes you from finding your zone to laying out your garden and how far you should plant them apart and everything else.  It’s a fantastic website because he has everything together.  So I didn’t have to choose 2, I could choose 1 website that had 15 other places that you can go to.

Dave:  Fantastic.  I’ll put a link in the show notes folks if you’re driving please keep both hands on the wheel I’ll put a link and you can just go there from the web.  Cristina, I had the other day on the show Susan Cohan, she’s a big designer from New Jersey.  And she says a lot of gardeners have been living in “zonal denial” the last couple of winters because they had just an absolutely killing winter.  We had the same winter here, we’re only a couple of hours apart.  What was your spring like for your garden?

Cristina:  I had everything come through but I tend to choose things that do well to Zone 3 even though I live in Zone 5.  So everything came through.  The worst hit were my trees from the ice storm.  I lost 1 tree.  It got just covered with ice then it snapped during the ice storm.  And it wasn’t because it got too cold.  It just was too much ice on it and it snapped it.

Dave:  For those of you global listeners, Toronto got hit with one of the worst wickedest ice storms in its history the week of Christmas Eve.  Two million people without hydro.  Half a million of them for almost a week.  It was quite the winter.  In terms of wisdom or advice for neophyte gardeners, picking the right backyard plants depending on zone is important.


Cristina:  Absolutely.  And if you’re doing container gardening, if you want to grow a shrub or a perennial on your balcony or on your patio, the best thing to do is get a large container, insulate the inside of your container with at least an inch of insulator, or you can get that silver insulation that’s supposed to be for houses and you can tape it on the inside.   Fill it with soil, and because the roots are outside rather than in-ground you need to get plants that are at least 2 zones colder than you are.  So if you live in Zone 5, you’ll want to get something that’s hardy to Zone 2.  Because roots are less hardy than shoots.

Dave: Wow.

Cristina:  It’ll save you tons of tears.

Dave:  You just blew a whole bunch of gardeners’ minds with the insulation because they don’t sell pots really that are insulated.  It’s a now a Dollar Store item.  That’s fantastic, thank you for sharing that.

Cristina:  I just go to the big box store and get some styrofoam if it’s square because then you can cut it easily.  Or if it’s round those are the harder ones, that’s where I get the flexible silver home insulation.  And then you just put it around it.  It really works, everything comes through.

Dave:  I’d like to change gears a bit on you Cristina and talk a bit about the passion.  I tell my friends that gardening is a lot more than just growing tomatoes and lettuce or flowers.  It’s a spiritual component, or a health component.  Can you talk a little bit about what you love most about gardening?

Cristina:  I thought about it and the growing, I think when I plant seeds and I start to see them growing, springtime when I start to see the shoots coming through the ground, the flowers when they first start to form and start to open, that’s what really wows me.  It keeps me hot.

Dave:  And your life has changed how? I know you’ve been gardening most of your adult life and since you were a child.  How has your life changed because of gardening?

Cristina:  You know it’s hard to tell because it’s always been part of my life.  But I don’t have a “Before and After” like some people do and that’s makes it easy to define what’s changed.  I would say just because gardening has that aspect to it, that you’re more grounded, probably more grounded than if I didn’t garden.  And more aware of the seasons because I’m out there gardening regardless of the seasons.  I’m more aware of what’s going on with the weather, with nature.  You just feel more connected.

Dave: Brilliant. For those of you who really like visual treats and like reading, especially the magic of soil and the gardening technical aspects, Cristina’s blog is brilliant.  Head over to make sure you also connect with her on social media on Twitter @cristinagardens.  Cristina, you’ve been gardening for 3 decades, you pretty much could grow anything you wanted now, but this season can you describe to our listeners, what’s your garden like this year?

Cristina:  Oooo … well when I first started I had a big hole because one of my trees had snapped.  So everything looked out of balance and I thought “well, what can I do here?”.  It seems like I have a really sunny west-facing garden which faces another house so I needed the privacy but two of my trees have disappeared now.  One was due to the ice storm last year at Christmas and the year before I must have picked a tree that had a disease because it succumbed to disease.  So I lost 2 out of my 3 trees.  After getting over my disappointment I thought what can I do here?  I think I have to go with the flow, it seems like Nature’s telling me to keep it sunny.  So I thought what can I do to keep it sunny?  And I started reading a lot about Keyhole Gardens.  I don’t know if you’ve heard about them Dave?

Dave:  Pretend I haven’t, share it with me.

Cristina:  It started developing over in Africa and they use it a lot in Texas.  It’s a layered garden that has a compost in the middle that allows it to not only be very rich in nutrients but it’s also stays moist longer which is very good for hot climates.  Now of course you know we live in Canada and it’s not that hot despite all our complaints about it.  It’s not that dry either.  So I decided to build a keyhole garden without the compost in the middle because I don’t think we have the heat that would allow the compost to decay fast enough so it would just be sitting there for a while because it doesn’t decompose as fast as it does in hot dry heat as it does in Africa and Texas.  So basically, you’ll love this, it’s called a Hugaculture Garden.  It’s one of those log gardens.  I took the old tree that had snapped, cut it into logs, and put it at the bottom of this raised bed which I made out of wire … Gabion Basket if you know what I mean.  And filled it with rocks and then at the bottom I put the logs and then I started layering it with first a brown layer, a green layer, a brown layer, a green layer and finally some organic potting soil at the top so I could grow vegetables in it.  So instead of working against, keeping on trying to grow trees where it seems like Nature was telling me don’t grow trees, I decided to use the sunny location and put in a raised bed and tried a new technique that’s been out there and I always wanted to try it, and it’s growing very well.

Dave:  Cristina that’s fantastic!  Everyone’s listening, their imagination just got fired up!

Cristina:  Sorry!

Dave:  Everyone who’s listening their imagination just got fired up, I’ve never heard of a Gabion Basket.

Cristina:  I could have just done rocks on top of each other, or some bricks on top of each other.  The Gabion Basket is used for rivers to keep the riverbanks together instead of allowing it to erode.  They’re really strong wire that you fill up with rocks so it stops things from eroding.   And the inside I used landscape fabric so the soil wouldn’t come out through the rocks.

Dave:  And the Keyhole Garden idea, brilliant.  There’s a drought, penalties for watering in parts of Arizona and California.

Cristina:  So it would be very useful there.

Dave:  I was just talking with Chad Hudspeth from Phoenix, he’s President of Endless Food Systems, it was 114 degrees Fahrenheit, what’s that, like 38 or 39 degrees Celsius?

Cristina:  Ridiculous temperatures.

watering flower beds

Dave:  They actually have to cover up to 70%, almost like a cheesecloth roof for a lot of their raised beds.

Cristina:  Yes, things would start to burn.

Dave:  Yes, it’s extraordinary.  I guess that’s man’s innovation, being able to grow food wherever they find themselves.

Cristina:  Exactly.  I love that.

Dave:  You know our half hour is rapidly racing away but we’re at the part of the show now, my favorite part, it’s called Five Quick Questions.  You get to drop pearls of gardening wisdom to our listeners.  Are you ready to play?

Cristina:  Ok.

Dave:  Fantastic.  Question number one:  What do you think stops most people from getting into gardening?

Cristina:  Thinking that they can’t do it.

Dave:  And how do they overcome that?

Cristina:  Just do it.

Dave:  <laughing>

Cristina:  I know … I’ve been on Twitter too long … 140 characters or less.

Dave:  Practice growing weeds your first year … I know I did.  Question number two: now this is on 30 years of gardening … What is the best gardening advice that you’ve ever received?

Cristina:  Really it’s just do it.  That’s the best advice I’ve ever received.  And it applies to everything.  I know it’s a Nike commercial but it also goes back to that really lovely quote from Yoda …”do or do not, there is no try.”

Dave:  You said something profound during the call is you never had a before and after, you’ve been gardening most of your life. That childlike quality, you know kids are fearless they’ll try anything.

Cristina: I have my injuries to prove it.

Dave:  Question number three: If you had just two websites to share with a beginning gardener, what would those websites be?

Cristina: I think I mentioned this before, I’m only going to say one website, I’d say go to Mother Nature’s Network and look up “Fifteen Handy Online Tools For Gardeners” and it’s for beginners and that should get you started as a beginner.

Dave: And that was Ramon Gonzalez?

Cristina: Yes sir, Mr. Brown Thumb.

Dave: Hey, I follow him on Twitter.

Cristina: He’s hilarious.

Dave:  That’s what I hear.  It’s hard to convey a lot of comedy in 140 characters but he does it well.

Cristina: He does!

Dave:  Now I’m in my third season as serious enthusiastic hobby gardener … my wife is in year 15.  As a beginner, I consider myself a beginner, what’s the best gardening book that I should read this year?

Cristina:  You know it’s like asking “what’s your favorite flower?”.  It’s really tough for me, because there’s so many different gardening books, and it depends on what you’re interested in.  Because it’s become so very specialized it depends on what you are interested in.  But because I’m from soils and I focus on soils I’ll tell you one of the best books that has come out this year on soil it’s a chap from Guelph actually, his name is Keith Reed and he wrote Improving Your Soil.  It’s a practical guide to soil management for the serious home gardener and it really covers in very simple language how to improve your soil.  And it’s very accessible.

Dave:  You mentioned Guelph.  We’re going to the University of Guelph this fall to do the Master Gardener course.  For those of you out there afraid of stuff, I haven’t thought about studying or going to school in 20 years, I’m a proud college drop-out.  Me and my wife are going back to college to get our Master Gardener’s certificate.

Cristina:  You’ll love this.  It’s fun and they don’t make it too hard.  They really do encourage you, the Master Gardener’s courses are really wonderful,  I did mine online through Dalhousie, and I really enjoyed it.

Dave:  Fantastic.  My buddy is going to go to the same university, this is totally unrelated, and he’s doing Aquaponics.

Cristina:  Oh nice!  That’s becoming very hot right now actually.

Dave:  He’s got a backyard full of fish and the tomatoes are monsters.

Cristina:  Is he watering the tomatoes with the water from the fish?

Dave:  Yes, he’s got the science going, you know the beds, and it’s fascinating.  I think aquaponics is cutting-edge 21st century stuff.  I mean this can really affect the planet.

Cristina: I think so.  I had someone come in and talk about it on #GroundChat.  Do you know @HandyHelen?  She came on to GroundChat and covered aquaponics, because she went on a tour in a greenhouse about it, and she’s also thinking of starting her own aquaponics greenhouse.  I’d say the only thing holding people back on that is the cost because there’s a lot of equipment and a lot of overhead to get it started.

Dave:  I look at aquaponics like golf.  Nobody ever wakes up and says “I’m going to go and spend $2000 on golf clubs”.

Cristina:  <laughs!>

Dave:  It’s always a friend that gets them into golf, and they’re always terrible at it in the beginning, but then it just grows on you.  Aquaponics is the same … “I’m going to grow fish, a fish-powered garden!”

We’ve gone complete off my notes here!  Question Number Five:  Look into your crystal ball … What’s the number one thing that every gardener should attempt to grow next season?

Cristina:   I’m going to be funny here … Something.  <laughs>

Dave:  <laughs>  We haven’t had that as an answer on the show yet, that’s fantastic!

Cristina:  I wouldn’t dream of telling someone else what they should or shouldn’t plant because everyone has their own likes and dislikes, and gardening is really about following your own passions, not some else’s.  So whatever your passion is, plant it.  

Dave:  I love that.  Fantastic.  You know the half hour just flies.  For those of you listening, make sure you head over to Cristina’s blog at  and please share her content on social media.  You can join the chat  @CristinaGardens and make sure you participate in #GroundChat every Friday at 2:00.  Do you want to take 60 seconds and talk about GroundChat?

Cristina:  Sure.  It got started as a way of me giving back to the community.  I’d looked through all the different chats and I saw that the one thing they really didn’t talk much about was soil.  I felt that soil, being the foundation of gardening, should be something that we focus on.  That’s how I got started with GroundChat, basically as a way to communicate with other people the importance of soil with gardens, and it just grew.  It started off with a couple of people turning up, and now the reach is …. I think the biggest number was 2 million people.

Dave:  Good googly moogly!  That’s a lot of gardeners.

Cristina:   Well, you know some of the other chats are bigger.  The one that’s been around longer is GardenChat.  That reaches 5 million people.  

Dave:  GroundChat is every Friday at 2:00 Eastern time.  You can lurk, or you can participate.  It’s #GroundChat.  I’ve got to get in on that, it sounds fun and I’m going to learn a ton.

Cristina:  Well this week we have Eric Vinge from Planet Natural and he’s going to be talking about natural fertilizers and how to use them properly.  Many people think “it’s natural” and then they overdo it and add too much.  

Dave:  Fantastic wisdom.  I hope you enjoyed the show folks.  I learned a ton and took a pile of notes.  Cristina, I’m actually going to give you the last word.  Do you have a pearl of wisdom or a note of encouragement for our listeners?

Cristina:  Well … Gardening will keep you sane (most of the time).  I don’t know if that’s a pearl of wisdom.

Dave:  I think we can use that.  That’s fantastic.  Folks this has been another edition of Back To My Garden.  I’m Dave Ledoux, your host, please join us again for an upcoming show.  Please share Cristina’s information on Twitter and participate this Friday at #GroundChat.  Thanks for listening, and have a great week everybody.  Happy gardening.

More Info:

Listen to Cristina tell us about How To Build A Keyhole Garden: