Friday, April 9, 2010

Food Production in Small Spaces: Fig Trees in Zone 6


I know the posts on my backyard food production challenge have been rather thin on the ground.  But I hope to make up for that somewhat with this post and a few others I have up my sleeve.  The technique outlined here pushes the edge of the envelope not only in terms of food production in limited spaces, but also in terms of cultivating plants outside of their normal hardiness zone tolerances. 

The hardiest figs are generally considered to do well in zone 7 or higher.  I'm in zone 6b.  Early last spring a hardcore gardener in my area showed me his Brown Turkey fig trees that he had planted in large tubs and pulled into his garage over the winter months. Though fig trees can reach 6 meters in height, these were only 2 meters, at most, above the level of the soil in their containers.  I was impressed and fascinated, enough so that this concept made it on my official list of goals for 2010.  Having taken up the challenge of feeding ourselves as much as possible from our own production, while also making a conscious effort to reduce our food miles and eat locally, some of our favorite items of produce have become rather scarce in our diet. We've lamented the fact that we could not grow avocados, mangos, or figs. Until we saw this method for keeping fig trees, that is.

I'm going to walk through this technique as logically as I can, though I'm not sure the pictures I have are going to make it flow very well.  Bear with me, and click on any of the pictures for bigger scale.  The basic idea is a large planting container with a water reservoir at the bottom which is kept filled as constantly as feasible.  The soil and the roots of the plant are held up above this reservoir with the use of wire mesh and burlap.  The burlap also serves to wick moisture up to the soil as the level of water in the reservoir falls away from direct contact with the soil.

The gardener who showed me his fig trees explained that one key issue was to make sure that the container the trees were planted in was UV resistant, otherwise the sun would make the plastic brittle enough to crack and break easily after very little time.  Having handles on the containers is also a really good idea, since they will need to be moved twice a year and will get quite heavy indeed as the plant grows.  He was using slices of large diameter PVC pipe to create the water reservoir at the bottom of the container. But this site (which includes designs for a different but similar self-watering container) argues against the use of PVC in container gardening, because it leaches harmful chemicals, including endocrine disruptors. Good to know, but who knows what's in the plastic planter itself.

I broke down and bought feeding buckets for large livestock at Tractor Supply to use as the containers.  Rather than using PVC for the water reservoir, I asked friends to save a bunch of dog food cans for me. Any tall can would do just as well, but it's important that all the cans in a given container be of identical or nearly identical height.  To allow water to move freely within the reservoir, I drilled a hole towards one end of each can on the side and another on the bottom, and arranged them all upright in the barrel. A few cans were made such that a can opener could be used to remove the bottom of the can as easily as the top.  Where I could, I did so.  The cans also have the virtue of not costing me any extra money.


Over the layer of cans goes a piece of hardware cloth, to help support the soil in a tidy layer. The hardware cloth was cut using a cardboard template traced from the bottom of the container.  After tracing and cutting the cardboard, check to make sure it's a good fit within the container over the top of the cans before cutting the wire to fit.  Over and around the wire netting goes a piece of burlap. The burlap must be sized to overhang the wire netting by enough to reach the bottom of the container. Burlap also has the virtue of turning up as packaging for various items. If you buy basmati rice in those 10-pound bags, there's a source of burlap that you won't pay extra for. If you can't find any for free, burlap is one of the cheapest fabrics you can buy. 

An overspill hole is needed at just the level of the hardware cloth netting.  This is to keep the roots from getting waterlogged.  I first drilled a normal hole and then used that hole as a guide for a mandrel drill bit which significantly enlarged the hole.  I wanted something that would allow me to easily check the water level with my finger and accommodate a garden hose.  Since I'll be sticking my finger in there fairly often, and since the hardware cloth is right at the level of the overspill hole, I took the precaution of crimping back the sharp ends of the wire so my fingers aren't at risk.

A watering tube is an option for filling the reservoir if you don't want to fill through the overspill hole.  This is a tube that sticks up above the soil in the container and empties into the water reservoir.  You could use bamboo if you have access to an aggressive stand that needs thinning. You'll just need to punch through the interior segments to make it work as a pipe. The bamboo will rot fairly quickly in damp soil, but it is non-toxic and cheap enough to replace each year if need be.  To make sure that the water flows easily into the reservoir, the bottom of the bamboo pole should be cut at an angle.  Angling the top in the same way also makes filling a bit easier.  However, I'm opting to forgo a watering tube entirely.  Instead, I'll be adding the water via the hole I use to monitor the reservoir levels.  Given that I'll have only a few containers to monitor for water reserves, I think this is fine.  If I had dozens of such plantings, I'd probably opt for the watering tubes.  I was told that a fig tree grown to full size for such a container will empty a such a reservoir in two or three days of hot weather.

I was also told that the roots of the potted fig trees will need to be pruned back severely about every three years, as the plant grows out and fills the container.  The guy who sold me the fig trees said this could even be done with a chain saw!  I suppose this root trimming works along the same lines as bonsai cultivation does. Pulling out a fig tree whose root ball has managed to fill a twenty-odd gallon container is going to require two people, no doubt, even with the container laid on its side. But it will also be an opportunity to check that the burlap is still intact, and to add some worm castings to the container to feed the tree.

So last Friday I came home from Flemington, New Jersey with three one-year-old fig trees: one each of the Neri II, Sicilian, and Verte varieties.  Fig trees like an alkaline soil in the 7.5-8.0 range, so I added finely crushed eggshell (a homegrown product) to the garden soil and compost mixture that I made for the fig tree containers. This study shows that pound for pound eggshells are nearly as effective as garden lime at lowering the pH of soils. Eggshells affect soil pH a little more slowly, but the effect is longer-lasting.  I was told to expect a small crop of fruits this year. The trees have shown really dramatic leaf production in the few days I've had them in their large containers.  We'll see how it goes as far as a harvest is concerned.

Aside from the fact that I'll be able to pull my fig trees into our garage for protection from winter weather, planting them in containers means that they can be placed on a driveway, porch, or any other space not otherwise useful for food production.  When we try to maximize what we produce in limited residential spaces, we need to use all available space, whether it looks suitable for cultivation or not.  Container gardening is one of the most versatile means of doing so.  Theoretically, these trees in large containers could be moved if we were to relocate. I don't expect we will anytime soon. But if you aspire to food production in a rented space or if you anticipate moving in the near future, this self-watering container for fruit trees is one you might consider. Just be aware that containers of the size I show here will weigh a couple hundred pounds when full of soil and a tree grown to the limits of that container.

I'm posting this technique at just the moment I'm trying it out for myself, because I've seen first hand that it works for this particular tree in my immediate area.  There may be a few tweaks and modifications I will recommend in a year's time.  But I wanted to get this idea out there for those of you thinking about what can be done in small spaces or in a cold hardiness zone.  Also, for what it's worth, it's apparently not too hard to grow new fig trees from cuttings.  So if you "invest" in a fig tree or two now, you could in theory have figs for the rest of your life, or share the wealth by passing on new trees to your community.  That's my kind of investment.

41 comments:

Tree Huggin Momma said...

I have potted trees on my list for some time in the future (and figs are a fave). So you don't hurt yourself when you move them, consider an appliance dolly (handtruck). I plan to plant mine in metal or wood, because I simply can't do the plastic - clay would be ideal but really expensive and not so sustainable....
I never would have thought of the water reservoir, I am wondering if I can use this method for several potted trees :)

Jody M said...

We decided to buy a fig last year and picked Hardy Chicago because it is supposed to be good to zone 5, I believe. We planted it in a pot and put the pot in the ground for the winter. It may have survived, but I can't tell yet. I think I see some green growth just starting.

But. I pulled three ripe figs off of it last year and....they tasted like sand. I don't know why. Too much water? Too little water? Not hot enough here near Gettysburg? Or maybe just the variety? Any suggestions? I would like to get more.

timfromohio said...

The water reservoir is a great idea. I'm looking forward to seeing your results. Question - do you think the same technique would work for olive trees or avocado trees? You mentioned the avocados - do you plan on trying these eventually? My kids love them and it would be a fantastic family project to start growing our own. Thanks for the inspiring work!

Sadge said...

I'm in zone 6 too, although some maps say 5. About 10 years ago, I inherited two potted fig trees from a gardening neighbor that was moving. They spend the winters, dormant, in my cellar. One Spring, after I'd moved them outside, a very late frost came through unexpectedly, and froze the tops back to the roots but they re-grew. Pots included, they stand about 5 feet tall. I've taken photos of my repotting process, and can get a post about it online for you soon, if you'd like.

Debbie said...

Was wondering if the cans would rust? If so you may have a problem there. Everything I have read about SWC uses plastic, how about food grade ie yoghurt containers instead?

Kate said...

THM, thanks for thinking of my back. We do have a dolly. But I also note that there are two handles on each of these containers. I'll be letting the reservoirs run dry and then expecting my husband's help when it's time to move them. Fortunately, we'll never have to move them far. I've situated them at the southern end of the garage they'll spend each winter in. Thirty feet is as much as any of them will ever need to be moved.

Jody, I think figs need some pretty serious summer heat to have good flavor. Do you get that where you are? I'll assume you knew how to tell when they were "ripe." Or maybe your trees are just young and not yet producing great fruit? Sorry. I don't have any definite answers.

Tim, in principle I don't see why this wouldn't work for other trees. (I'm going to use the same basic technique for potatoes this year, btw.) I have seen olive trees in containers in Europe, but I have no idea whether they produced a crop. I doubt I would ever try avocados. First of all, you need a male and female from what I understand, and I would be loath to keep up two containers for a single harvest. Secondly, my suspicion is that they need more warmth than our unheated garage would provide. This container "trick" can only push the hardiness zone thing so far. But those living in the next warmer zone than me might get away with it.

Debbie, the steel cans were made to hold wet foods, so I'd be surprised if they rusted. Even if they did, my impression would be: so? If it would hurt the roots of a fig tree, it would be news to me. I don't know for sure, but I doubt that plastic yogurt containers could stand up under the weight of that much soil and the growing tree.

Jody M said...

This summer was cool and wet. Maybe it was just a bad year. I picked them based on what I'd read on the internet: brown/purple, soft, scented. They just didn't taste like much. I'm going to hope for the best this year, probably put it in a larger plastic pot and maybe bring it inside next winter. I may get another of a different variety for comparison.

Joel said...

>who knows what's in the plastic planter itself.

Oo, I do! (raises hand)

Almost all of them are made of HDPE (high-density polyethylene). There will be traces of catalyst, which is usually an aluminum/titanium oxide ceramic.

There's also almost always a pigment added. In yours, it looks like either lamp black or magnetite. Either will stand decades, maybe centuries, of UV exposure, with damage only to the surface layer of plastic, and neither is very expensive, so the manufacturer probably added just enough to avoid compromising the strength of the plastic.

There will be traces of free monomers, but ethylene isn't very toxic in such small concentrations. In fact, it plays an important role in both the regulation of soil ecology and the ripening of fruit. Either of those sources would probably give off more of the stuff than your bucket does.

Last, there will be some oligomers, but probably very few will leave the plastic. The soil tends to be fairly good at metabolizing this kind of chemical (paraffins etc.), from this particular plastic.

HTH.

Leigh said...

I'm in 7b, so fig trees grow well here, in fact I have a small grove in the back. However, it's an olive tree that I'd love to have. After reading this post, I realize that the only thing I lack is a place to pull it in to during the winter, i.e. no garage. I should consider a spot in one of our outbuildings. Hmm...

timfromohio said...

I received a Lee Valley gardening catalogue in the mail yesterday and thought of this project - they sell pairs of large straps with handles specifically designed for two people to move large potted plants. Might save some lower backs later in the season when it's time to move the trees inside.

Just an idea.

LindaSue said...

Meyer lemons are absolutely the best most flavorful lemon you can get. We lived in Florida for about 15 years and I got them whenever I could. I would use a juice and freeze the juice in ice cube trays and then put the cubes in bags in the freezer. Makes the bestest lemonade you could ever want.
The fig trees are an envy. My mother in law makes the best fig preserves in the world.

Could you tell me where you ordered the fig trees and meyer lemon trees. I live in SE Ala and could grow them both here.
Thanks so much

Anonymous said...

Plant hardiness zones are fairly new to the UK, in fact the zone maps of GB seem to have been created in response to the internet and needing/wanting to compare your zones with our climate.
I find them quite difficult to interpret. According to the data I've found, I'm zone 8, which may be true from the point of view of minimum temperature, but we never achieve the consistent hours of sunshine or average temperatures of US zone 8 areas like California and southern states.
Figs in the UK do sometimes fruit, but it's a bit hit and miss, citrus plants need cover and the first avocado tree in a garden (as opposed to in a glasshouse)to fruit was recorded a couple of years ago, but it was in a very sheltered spot in a city. Apricots and other early flowering fruit trees need covering at night to protect the blossom in my area.
So I'm intrigued, because according to the US equivalent I should have groves of olive trees in my garden!
Hazel,Oxfordshire,UK.

Kate said...

Jody, I'm pretty sure that different varieties of fig show ripeness in different ways, so you might want to do a little research if you're uncertain what the indications are. Some figs droop slightly as they become ripe. Others don't.

Joel, leave it to you! Thanks for the information.

Leigh, I'd love to hear about any sort of plant you use this method for. I'm thinking of eventually putting my citrus trees in containers like these. Right now they're pretty small. We bring them in the house each winter though, so we'll need to make sure we have room for such large containers.

Tim, that sounds like a good product. Lee Valley has great stuff, but very spendy. I may check it out though. Thanks for the tip.

LindaSue, I went to Flemington, NJ to pick up my fig trees. I have no idea whether this guy ships his trees, but I didn't get that impression. Do a search for Bill's figs and you should find him online. I ordered the Meyer lemon from Territorial Seeds Not cheap at all, but it's a fairly big plant already.

Hazel, you're absolutely right that hardiness zone is not the be-all, end-all of growing plants. It's only one factor - the lowest temperature reached during an average winter. So many other factors are equally important: frost-free weeks/year, how hot it gets during summer, precipitation, etc, etc. I once rented a place in California with a fig tree that produced fruit each year but never ripened. Not all parts of California have the hot weather needed for good figs. And as for olive trees, I've wondered about that myself. I spent time in Umbria in the winter. It seemed as cold as our winters here in Pennsylvania, with snow on the ground, and yet Umbria produces superlative olive oil. It may bear looking into.

dltrammel said...

Another plant you might want to look at for container gardens, especially if you can bring it in during winter is the SE Asian plant Moringa.

Try this thread, I have posted pictures on the second page. My seedlings are at 6" after just 2 weeks.

http://zombiehunters.org/forum/viewtopic.php?f=39&t=38292

The leaves can be eaten and have a taste like spinach. It produces seed pods much like green beans. The root can be ground up to make a horse radish like sauce. And the stems and branches ground into power help purify dirty water.

For containers they work best when topped at 4-5 feet, so they should be easy to move and store inside.

daharja said...

I don't know what growing zone we are in, but I'm in Dunedin NZ, we get about half a dozen snow days a year with max temps of 30C and minimums dropping below zero in the winter, and we have a fig tree on our property producing fruit.

It's in a really sunny spot, and doing well. I'm looking forward to yummy figs when they ripen!

Thanks for the tip about them growing from cuttings: I hadn't considered that and will take a few strikes to see how I go. A few more fig trees would be welcome, as we have 3 acres to fill!

Anonymous said...

Kate, it'd be interesting to see how olive trees worked- the best olive oil I've ever had was from a couple who lived down the road from the villa in Spain we rented for our honeymoon. We brought it home in old cola bottles.

I think average temperature and sunlight would be more important though. According to this zone map of Europe http://www.uk.gardenweb.com/forums/zones/hze.html most of France and N Spain is 8, Italy and the rest of Spain mostly 9.
European olive trees are generally grown commercially not much further north than the South of France, but there may be more hardy varieties available, like there are with grape vines. I wonder if you can use olive leaves for anything? I seem to remember seeing them in something cosmetic, but that doesn't mean they actually do anything...
Hazel

Kate said...

dltrammel, my husband just told me about this plant yesterday. I'll look into it to see whether our unheated garage would be warm enough for it. I do wonder whether a tropical plant would adjust to a winter that forces everything native into a dormant period. Figs are used to that routine. But our citrus trees we have to keep in the house over the winter. And there's only so much room for container plants indoors.

Daharja, sounds like you're in a significantly warmer climate than we are. Our average low temp is -5 F, which I think is something like -20 C. The garage provides a good buffer for the temperatures though, even though we don't heat it. If you want to propagate figs from cuttings, check out my recent willow rooting hormone post if you haven't already seen it.

Hazel, I agree that it would be very interesting to see how olives do in containers. I don't have any immediate plans to try it myself. My intuition is that they wouldn't do very well here. I'd guess they like a dry hot summer - the Mediterranean climate. We don't have that here. But I'd be delighted if someone showed otherwise.

timfromohio said...

Sorry - one more question for you regarding container trees - I'm now looking for olives, maybe figs, and lemons. Based on your reading, do you think your trees would benefit greatly from being in an unheated greenhouse during the growing season? Still overwinter in the garage. I'm in NEOhio (zone 5b) and am looking for yet another justification to build a greenhouse.

Jody M said...

I will look into the ripeness of Hardy Chicago a bit more, thanks!

Also....it lived!! It made it through the winter in a clay pot burried next to the house! In zone 6! Yippee!!!

Tamar@StarvingofftheLand said...

Kate -- Sometimes reading your blog makes me feel like such a slacker. We, too, live in zone 6b (some say 7, some say 6), and love figs. We bought a brown turkey fig last year, and just planted it right in the ground. Over the winter, we packed straw all around it and wrapped it up. We unwrapped it a couple weeks ago, and it did fine -- but we're expecting a frost this week and I'm going to have to cover it again. I think the pot method may be the more dependable. Let's compare notes in a few years!

Kate said...

Tim, it's going to be mere speculation on my part to answer your question. My citrus trees will come inside the house in winter. And I'll pull them inside again in spring if we have any frost forecast. I doubt the citrus would mind a greenhouse existence over the summer in the least, provided of course that they had plenty of water. The figs I'm even less knowledgeable about. Again, I doubt they'd mind, but I don't think they'll need it. Where they're situated on my property they have great southern exposure and shelter from prevailing winds. I think they'll get all the heat they'll need to ripen good figs during a PA summer.

If you think figs would need extra warmth to ripen in your area, it's as good a justification as any.

Jody, congratulations. And happy researching.

Tamar, why you feel like the slacker when you're the one doing more work is beyond me. I chose the container method precisely because bundling up and then unbundling fig trees sounded perfectly tiresome to me. The containers will be heavy to move, it's true. But it'll take much less time to do so. Also, my understanding is that figs can take a light frost, just not a hard one. We're definitely not out of frost territory yet where we are. Unless they call for a really bad one, I don't plan to move mine until autumn.

Dani said...

we live in zone 9b so fig trees do well here..we have a Brown Turkey and we love it....we did start a second one by simply breaking off a twig, rooting it in water and then planting...its about a foot tall now in a pot..we also have a nectarine, a peach and an apple tree, strawberries, boysenberries and a vegetable garden...plus a duck who eats alot of the bugs...she also gives us a egg a day...

Kate said...

Dani, sounds like you're well on your way to producing quite a bit of food. Nice job!

Chris said...

I think potted plantings are great. Great post! I planted a Brown Turkey Fig two years ago and I am hopeful that this year we will get a good harvest.

Kate said...

Chris, thanks. Did you get any fruits last year? Your short post on your tree didn't say.

Chris said...

Yeah, we got a few. This year will be the real test. I may need to to some pruning on another tree to allow a little more sunlight to reach the fig. I am just looking forward to some figs!

Kate said...

Chris, good to know. I was told by the fig tree vendor that we should see a small harvest this year, perhaps a dozen figs per tree. We'll see...

timfromohio said...

Another question for you regarding this container technique. Is the idea that the roots penetrate the burlap and grow down into the water reservoir? Or, is water supposed to wick up into the soil? If it's the case that the roots are supposed to grow down into the reservoir, do you plan on top watering at all until they grow long enough to get water on their own?


Planning on getting two Meyer lemon trees and several olive trees and want to make sure that I understand the technique correctly prior to moving out with this project. Thanks in advance for your input.

Kate said...

Tim, in my mind, it's up to the tree. I don't know whether fig trees will want any roots actually dangling into the water. If that works for the tree, I'm sure it'll figure it out. If not, I think the plant is smart enough to refrain from putting roots down there and just allow the burlap to wick moisture up to the soil. The beauty of it is that we can use this technique with various trees or plants and each species can decide what's right for it. Some plants, I'm sure, would love roots right in the reservoir, while others wouldn't. I won't know whether fig trees like this or not until it's time to trim the roots in a few years. But either way it won't change my routine of keeping the reservoir full.

timfromohio said...

OK, last question I promise! What size container did you opt for? I read that for container growing of trees you might go up to 25-30 gallon size. I saw 25 gallon capacity ones on tractor supply site, but they did not appear to have the handles like the ones you show in your pics.

Thanks!

Kate said...

Tim, the containers I have and the ones that my gardening friend uses are 70 quart (17.5 gallon) muck buckets. The volume of dirt is reduced by the reservoir. If I could have found a 25-gallon container, I probably would have used it. But considering how heavy these containers are now with pretty small trees so far, the size we have is probably a good choice. I plan to use "tea" from my worm bin to feed each of the container-grown trees. That will compensate for the limited nutrients in the container.

Anonymous said...

I read your post with interest because we've been talking about figs as well. I live in SE PA which really now is zone 7...anyway I was putting my garbage and recycling out in those rolling platic cans the township provides when I got this idea. You can buy trash cans on wheels similar to the what the township has, they might make a great container for a fig tree? Here's a 35 gallon model with 6 inch wheels. http://www.acehardware.com/product/index.jsp?productId=3685746

Kate said...

Anon, it's an interesting suggestion. My concern would be about how top-heavy it might get as the tree grows, and how much weight the wheels could support. But wheels are pretty awesome when it comes to moving heavy things!

meemsnyc said...

This is a great informative post, thank you! Question, Do the dog food cans rust?

Kate said...

meems, thanks. Please see my comments to Debbie about rust.

william addy said...

interested in buying some fig cuttings if you sell.my e-mail address is waddy47@yahoo.com thank you,bill

Kate said...

William, I'm not sure yet whether I'll have cuttings to sell. I think this first year's prunings will be minimal, and I plan to try starting a few new trees myself. But I can let you know if I find otherwise. Whereabouts are you located?

The Cottage Garden Farmer said...

I dug up a couple of suckers from a large fig tree that grew in the garden of a house we used to have in France,(they throw loads of suckers from the roots in the open) and they all survived the journey home to England and grew well. One is now about 8 feet high and about four years old, out in the garden border, and has survived winter outdoors without any protection, and fruited quite well last summer, which was sunnier than average. Unfortunately I didn't watch it well enough and the birds got the fruit!Very annoying. This winter has been unusually bad for us and I'm hoping the fig tree will still be ok.
I think light levels have a big influence as well as temperature on many plants. But it's surprising that some do better than you might expect - my pomegranite tree and my lemon in a pot have survived several winters, whereas my olive died last year? Good luck anyway, will be checking back to see how you get on. kathy

Kate said...

CGF, congratulations on your successful cutting. That's quite a feat. When we lived on the west coast, we rented a cottage with a fig tree. The raccoons ate many fruits long before they were ripe. Fortunately we didn't begrudge them too much since it was never quite warm enough for the tree to truly ripen them. I too am finding that it can be hit or miss with potted plants.

timfromohio said...

Well, I never managed to get the trees done last year but am in the process this year. I'm wondering, now that you've had a year with the system described, how well it's working and if you'd change anything you did. I have a Meyer lemon, an olive tree, and am going crazy and trying a coffee bush. Was planning on getting the containers this weekend and setting up the system.

Thanks for any year-later input you can provide!

Best Regards,

timfromohio

Kate said...

Tim, I appreciate the question. I'd like to hold off on answering until I see how our trees came through the winter. So far we've pulled them outside but they seem very reluctant to wake up from their winter slumber. I plan soon to add a little more soil to the containers to make up for the settling that happened after planting last year. I thought I would need to prune this spring, but so far their shapes look good and not in need of much tweaking. Will post later when we see how they do later this year.