Do you have limited space for a garden? Join us for an overview of what it takes to create and successfully grow a variety of edible plants in containers. We will cover the basics of how to choose a container, types of soil to use, watering, fertilizing, and sun for veggies, herbs and fruit.
Greg Letts worked for more than 30 years in the specialty outdoor industry as a retailer, manufacturer’s representative and business owner. He became a Master Gardener in 2019. He volunteers weekly at Our Garden in Walnut Creek, currently coordinating the watering team. His home garden of many years includes year-round vegetables, small fruit trees, and potted citrus trees.
um so tonight we’re going to talk about uh edible plants in small spaces primarily um probably primarily with containers and the reason uh we end up using containers is because we might have a limited space in on a patio we might want to add different plants uh and but not necessarily full-size plants um some of the other benefits are transportability you’re able to move that plant around the yard as needed um you may want to be adjusting for pH in the soil so for instance it’s easier to adjust the pH for blueberries in a container than it is in the ground and of course some of the some of the cons are is the expense of buying pots um they can be pretty expensive you’ll end up using more water you’ll end up using more fertilizer and you’re a little bit limited in what you can grow though the selection is still great so the common elements we’ll go through in container gardening is the containers themselves we’ll talk about soil and how it’s different than ground soil we’ll talk about the differences in watering versus the ground we’ll talk a little bit about fertilizing and then we’ll talk about uh sunlight and so let’s jump right into the containers so first up we have glazed ceramic containers um the benefit of these you can get them in all kinds of colors and shapes um they they hold moisture in well um they’re probably about the most expensive those so for an 18 20inch pot they’re going to go start at about $60 typically and can go up well over $100 they’re also pretty heavy to move around if if you’re going to end up doing that next is terracotta containers these have kind of a classic look to them people like to use I use these for my citrus trees um they uh the difference between those and the previous glazed ones is they’re only fired once in a kiln and so in doing so they can tend to be a little bit fragile um my dog had knocked over many of these they can also um they they they’re also relatively porous so moisture can pass through them uh they actually breathe a little bit and so you end up watering more with these the price range on these can run anywhere for an 18 to 20in pot they can run $50 to $100 or $50 to $80 depending on where they came from the Italian ones are fairly expensive and the ones with more detail like the pots on the left there are more expensive than the basic ones on the right uh relatively new is the lightweight fiberglass containers these are fairly expensive they’ll run about $100 for a 18 to 20 inch pot um but they’re super lightweight um they come in a bunch of different colors and so they’re relatively easy to move around if you if you’re going to be moving pots around on your patio or on your porch next up is plastic containers these are probably the most affordable of the bunch um you can get basic plastic pots for about $15 and they can go up over 50 depending on the detail on them um they’re very lightweight they typically have great drainage holes drilled in them so water moves through them well um and uh all kinds of colors and shapes are available in those also relatively new um for home use is the galvanized steel containers these were cattle troughs they’re whether for feed or for water um and a lot of people are using them at home these days um they’re fairly expensive because they’re fairly large um they can replace a a raised bed um they’ll run anywhere from $100 up to well over $200 uh depending on the size of them the they’re not it’s not something you’re going to move around your yard once they’re there they’re there um and they some only sometimes comes with it come with a hill the holes drilled in them so um you’re going to want to drill a multitude of holes in there so it drains properly the other the other consideration with these is uh the steel can get hot on hot days and so that may either require more watering or it may require uh shading the uh the edge of of those containers some of the master gardeners have these and they’ll drape burlap over that sunny side next up is wine barrels and so I have a whole sideyard of these al between my house and my neighbor’s house and um they were very affordable a few years ago you could get them for4 or $50 now they’re about $80 still a good value for the size of the container um it’s kind of a rustic look so you’re going to have to want that uh but uh you can you can fit a lot in there and that’s why I like using them you generally want to get them up off the ground because they last maybe eight or 10 years before the bottoms rot out um or and the wood deteriorates um so and they’re they’re also porous the wood is porous kind of like the way the terracotta ones are and so um you’ll end up watering a little bit more with these but the one consideration is when the bottoms rot out it it even if you set them up on 2x4s it can enable roots from elsewhere to grow in so I had I had one container last year that didn’t do that well one of my wine barrels the plant didn’t do very well in that in there and I have a redwood tree about 15 feet away and what it had done is set up roots into into the container and basically fill the whole space up with um with redwood roots so I cleaned that out and and changed the soil but you know that’s still a possibility with with other trees as well if the bottom rots out and then other possibilities are as creative as you want to be so down in the lower left is a 15gallon uh tree container they actually sell these um at at nurseries even if you just want to buy them without the plant but um this is from some tree that I got and I use it for uh potatoes um rather than putting potatoes in the ground because once potatoes are in they’re there forever um so uh I I do a couple of 15gallon containers for for potatoes in there um the one in the middle is a container put on legs this is actually my neighbors he grows onions this way um the one on the ones on the right are grow bags and uh the advantage of those is you know say you grow a bunch of tomatoes in the summer but you don’t want to keep pots around all year and so um you you fill them with soil grow the tomatoes and at the end of the season you fold them back up and and can store them away till the next spring the one on the upper left is actually one that I made out of um I cast it out of Portland cement uh just to try and create kind of an antiquequy kind of thing not everyone’s going to do that if you’ve seen uh many of our talks we always talk about the four foundations of success the um and in this tonight we’re going to talk about how it appi soil applies to containers the differences in watering uh aation is still important be having air and water being able to percolate down through the soil and we’ll talk a little bit how the sun and how it pertains to uh containers so I’ll start off talking about what exactly soil is so in the ground soil is about 45% minerals about 5% organic matter and the other half is air and water and so 25% air 25% water there tends to be little channels of air going down to the roots as well as little capillaries that trickle the water down through the soil but with containers the soil is going to be a little bit different than that most people are going to use a bagged product and um here’s two two uh high quality bags that you that you’ll see in stores in nurseries and if you look at the list you know the primary ingredient is going to be forest products it’s going to be fur bark or shredded redwood or Pete moss and um there’s not a lot of minerals in that and so a quality product what it’s going to do is add other amendments to that that um will boost the nutrient value um and um and make it more than just a just a um a forest product so there’s in these in both of these there’s earthworms there’s chicken manure there’s feather meal there’s bat guano there’s kelp meal all of those have have macronutrients in it um and uh mostly put in there as a way to add nitrogen to the soil and so if you look at the two pictures on the right side there you know the extent of the mineral content is the the pummus or perlite those white flexcks that are in there so not a lot of minerals in there but the other advantage is is this gives great drainage you don’t want to use garden soil um because it it it’s not going to it’s not the water is not going to percolate through the way the way it needs to because really the only way out of a container is through the holes you’ve got in the bottom with you know in the ground the water can go everywhere another option is is to make it at home and so this is a a mix that a number of the master gardeners use um and it’s just equal amounts of coconut core which is a byproduct of the coconut industry it’s all shredded up um there’s compost in there which adds some mineral content in there as well as some nutrients and then there’s vermiculite or perlite which helps add some airspace to to the mix and so what you’re going to do is you’re going just going to blend that up uh really thoroughly like the container has on the left and the reason you want to do that is because you don’t want to have layers in the soil particularly in a container um because it’s going to affect the way the water flows through there it it can go uh it can get stalled out if you’ve got different striations in there so this is a this is a lab video that you can see on the internet it uh and so what you’ve got is two layers of lom one above one below and through the middle of it is a layer of clay and you can see how the water that’s dripped from that spot above just stalls at the clay and and stops percolating through and what we’re going to want is water to go all the way through the container all the way to the bottom so so it it it wets all the roots um and and so you you you know you intuitively think yeah clay is denser than lom soil is and so that’s to be expected but it also occurs with sand which you think is well counterintuitive it’s it’s relatively loose and you expect the water to flow through there differently than it does the lom but it can stall the same way and so when you’re when you’re putting soil into a container you want to blend it up well so the water can move through it evenly so what are the watering needs for a container well it’s different than inground because you want to make sure it’s flowing through the whole container you want and you want to be watering edge to edge of that container um and so I I think there’s a tendency where people end up having problem with plants and containers is they may just water at the base of the plant and not go all the way across wallto- wall um or they might have just an emitter or a small coil of drip system going uh wall to- wall or going just around the stem and not watering the whole thing personally I prefer to hand hand water containers just because it’s it’s more intentional um you can see how the watering is going and you can make sure that it’s coming through at the bottom where with a drip system you might not always have that and also you can water additionally as needed or less as needed so for instance you take the last couple days we’ve had it was in the 80s over the weekend and it was in in the 60s today at least here in Danville um and that’s different water for containers that’s um additional water over the weekend and and less today so um it enables you to be flexible on that if you’re doing it by hand um you can use a moisture gauge to check up check moisture in that soil and that’s a that’s a good thing to do kind of do it in several different spots in the container to make sure it’s uh it’s moist all the way around one of the limitations of a moisture meter is you can only check it really as deep as that moisture meter goes and they’re usually just about six or eight inches long um but you can’t really you can’t really use a soil probe like you would in a ground bed um and be taking core samples out of the soil so you can’t really do that in a container just like on the ground you want to be mulching the mulching your containers you want to be adding a layer of some organic matter to the to the top of that of that soil um it does a couple of different things it will it will um moderate the soil temperature it will reduce the amount of evaporation you have and so this is this is a ground soil example um from our garden it was an 85°ree day and the bare ground was 132 degrees on the surface which is pretty high temperature i mean really most microorganisms die at 140 which is why you want to cook things over 140 um and so pretty high temperature there even the surface of the mulch was 126 degrees um and then you can see where the straw was moved out of the way the surface soil below that was damp and it was uh uh kind of in the sweet spot of 75° for veggies 75 to 85° and that that mulch can be anything in a container you can use wood chips you can use grass clippings you can use crumbled up leaves um you can use straw anything that’s going to give you kind of a kind of a covering of the soil you can use compost um but compost breaks down pretty quickly so you’d be doing it more frequently than you would for some of the other materials okay talking a little bit about fertilizer so um we’ve got some great talks on fertilizer that are going to take the whole hour and so I’m really just going to go over some basics here um and encourage you to check out our other fertilizer and amendment talks that we’ve got on YouTube so um really in containers to get the best results you need to fertilize regularly because as you water and you’re watering to the point the water is draining out of the bottom you’re you are washing some nutrients out so for instance with citrus trees in pots they usually will suggest fertilizing once a month and um for the growing season so for spring summer um you’re watering every or you’re fertilizing every month um and in a container it’s typically a couple tablespoons stirred around but you want to follow the label directions um more fertilizer is not better and it can actually be worse it can be damaging to the plants you can kill the plants um and you can fertilize for different needs so whether that’s vegetable and fruit production or whether that’s for bloom say you’re planting a rose bush in a in a container um you can do fertilizers to accommodate both of those things so the the basic macronutrients of um uh in the fertilizers are nitrogen phosphorus and potassium kind of an easy way to think of those is nitrogen sends the plant up has the plant grow phosphorus sends the plant down it helps develop roots and potassium is kind of the allaround in that it it encourages bloom and and fruit and so with a starter fertilizer those numbers these are percentages of weight so with starter fertilizer being for instance 462 on this particular product it makes sense so you you want higher nitrogen to to help the plant grow you want phosphorus to develop roots and you’re less concerned about fruing and flowering at at that point when you’re just starting out then you may go to a balanced fertilizer on going through the season um where it’s equal amounts of each and then maybe you’re just looking for bloom and so this particular bloom fertilizer has um a significant amount of phosphorus and potassium in there and that might be something that you might use as a with a rose bush in a pot for instance and here’s an example of overfertilizing so um too much is not a good thing okay let’s talk a little bit about sunlight requirements um if you’re growing veggies whether it’s in the ground or in a container you’re ideally want to hit that eight hours a day of sunlight the great thing about containers is you can move them around to accommodate that so for instance in my backyard I’ve got three beds on the back side of the house that um in the summer it gets that eight hours a day on all three beds in the winter it gets that eight hours of sun only on one of the beds um and when you’re doing things in a container you can move them around to to get that additional sunlight when you’ve got that low sun during the winter um containers are more affected that by hot or cold than the ground is and so on the really hot days um you may have to shade that container or you know as I mentioned the burlap on the on the uh troughs um uh to protect it you may have to water a little bit more um to keep the soil cool and moist um and then on the other end you’ve got cold so for instance I’ve got a um fig tree in a container that sits out in the middle of the patio during the summer and then during the winter I move it against the house on the back step um where it gets a little radiant heat from the wall um but it’s and there’s a little bit of an overhang to protect it from the cold as I said at the beginning um you can’t plant everything in a container um pretty pretty difficult to get good results with a you know full-blown 6 or 8 foot uh indeterminant tomato in a in a 10gallon pot um those roots will go down 4 feet or more and they’ll spread a couple of feet wide but there’s lots of things you can do um there’s shallow and and medium rooted plants and lots of different choices there the um um there’s lots we had it at our sale which actually continues again tomorrow at at our garden and then at Richmond Library this weekend uh on Saturday but um there’s dwarf tomatoes you can do there is just smaller determinant tomatoes you can do in a in a say a 10gon pot and then there’s lots of other shallow rooted things all kinds of greens you can grow i like doing broccoli in those wine barrels I have in the winter um more so than cauliflower cauliflower you get one head and you’re done where if you get a broccoli with multiple side shoots on it then that’s then that’s uh that that can go for a while um but spinach lettuce kale chard all of those can can go in containers um beans and peas can go in containers um I’ve grown beets in containers and I I’ve grown garlic and I’ve got garlic in some of my barrels right now um and then leave the deep deeper rooted plants for the ground there’s actually a great uh website um called All-American Selections where they they evaluate different plants and you can you can filter on that website for containers for the recommendations of different veggies that they that they’ve given awards to if you’re not familiar with All-American um their mission statement is to promote new garden varieties with superior performance judged in impartial trials in North America so it’s a nonprofit that does that um and we’ve grown it we’ve offered a number of their plants at our at our uh master gardener sale there’s also uh some listings on on our contraosta master gardener website under the edible gardening section okay so if you’re just going to plant up single plants this is a good way to do trees um so for instance I do a fig tree in a container um reason being is I don’t want a ton of figs i’m good with a dozen or so figs maybe two dozen and that’s enough for me um my neighbor’s got a very large tree and he gets a ton of figs but I I don’t I’m fine with a dozen or so and so that can go in a container um I do strawberries in containers just because I I tend to watch it better um I make sure it’s watered properly um I can fertilize it and um and it keeps some of the bugs out that that can be so troublesome with strawberries so that goes well in a container and then I also have a number of citrus trees in containers it allow allows me to do more varieties i do a couple different lemons i do a couple different oranges i do kumquats um and I don’t have the yard space to do all those as full-size trees so the care for for instance trees in in containers is um they need some maintenance every couple years so for instance the tree on the right in in that picture is probably I don’t know three four or five years old hasn’t produced any fruit yet is still pretty small but um but that’ll get rootbound and need to go up to the next size pot you know after it’s been in that pot for a couple years and so um and then then up to the next pot until a final size that you that you want to max out at so the way to do that is you’re going to tip that pot gently on its side say on a plastic tarp uh pull the plant out kind of loosely shake off some of that that uh old soil off of there you can also hose it off a little bit too and then repot it up to the next size um uh using fresh potting soil and with fertilizer and um and so that pot started out in that in a smaller container and that that’s about that’s probably eight years old and it’s and it produces a bunch of lemons for its size and um and that’s been repotted a couple times and then the next one on the left is uh an orange tree that um is a different variety than the other ones I’ve got and that’s probably as big as I’ll go with that pot and and um that’s been potted up repotted a couple times in that container um so uh the one thing with citrus you want to be careful of is they’ve got a lot of fine roots right under the surface and so you want to maintain the same soil line in that container that you had in the previous one so that so that you’re not you you want to be careful not to damage those roots and but you don’t want to suffocate them with too much soil on top of them or leave them exposed by planting it up too high and then fertilize as directed i usually do a top dressing of of compost on there and then always mulch on top and on these I tend to use wood chips but you can use bark you can use grass clippings you can use leaves anything that’s going to kind of protect that surface and then you can do multiple plantings um in the larger container so here’s one of the wine barrels that I’ve got and so this was a freshly planted uh tomato plant last year i added a couple small pepper plants on either side of it there’s a basil plant in front and then a little tuft of of thyme over on the side i also like adding ntorium seeds to some of my containers um it gives great color it shades the soil so if you’re not going to put a some kind of mulch on top of it covering it with a you know with a nersium plant also helps do that too uh and then on the right side is a freshly planted tomato plant with some maragolds in there okay so um the season doesn’t end at the end of the summer um you can do additional planting for the fall and it might carry on through the winter so on the right I’ve got a broccoli plant there and um this works really well in a wine barrel um uh you want to get a variety that has side shoots to it so so it’s not just one head and you’re done um and then I’ve also got some herbs planted in there around it and then on the left um after That crop came out of the summer i forget what was in there but I had a handful of of collected parsley seeds and I just spread them out in that barrel and uh miraculously they all came up so got a lot of parsley u but we use it every day so it’s great another option is to put a cover crop in there um just like you would for any inground bed it feeds the soil with a variety of roots it keeps the microbes active in that soil and then when you chop it down the roots will stay in the soil and uh provide organic matter so do something with maybe six or eight different kinds of seeds in there and let that grow in there for the winter and then chop it down in the spring before planting whatever you’re going to plant in there so for instance on the left there is is a chopped up broccoli plant um after that was done so I left the roots in the ground chopped the top up and into small pieces and spread it out over the surface and then I would spread compost over the top of that and let that kind of break down naturally in the soil um as we were talking about earlier maybe you’d grow tomatoes in in a couple of pots every year and um you don’t do anything during the winter and so um a good idea is to rinse out the pot and and maybe give it a 10% rinse a 10% bleach rinse through it to uh kill any organisms that might still be there um if you’re not going to plant anything in a container but keeping the soil till next year um it’s a good idea to at least cover the soil to protect it from the elements during the winter from the rain and or any sun and you can do that on the right there which I did with straw what you can do with you know grass clippings or leaves or whatever just to protect the soil during the winter okay so just kind of a quick summary here um you got many different options for containers they have different properties as far as price or or weight or um appearance and so there’s all kinds of different options you can have um you you want to use qual quality pointing so quality potting soil which has uh lots of amendments in it so you’re so you’re adding some nutrition back into all that forest product that’s in typically in there um you always want to water all the way across the pot not just uh at the base of the plant and for best results you want to fertilize as directed on the fertilizer bags um and with that you’ll be able to grow edibles year round um in in small spaces