Container Planting: An Interview with the editor of GardenMaking Magazine

I always have big ambitions for my container plantings each year.

Simply beautiful! That sums up my master plan perfectly. 

But somehow my containers always end up being... well, disappointing really. By mid-summer they always look a bit forlorn, which is a long way off from my originally stated goal of "simply beautiful".

Every year I aim to do better, and with that in mind, this spring I have sought out some expert advice. 

Beckie Fox is not only editor-in-cheif at GardenMaking magazine, she is also the author of a book on container gardening: The Potted Garden: Creating a Great Container Garden. 

Who better to turn to for a little bit of sage advice?

In case you aren't already a subscriber, this is GardenMaking magazine. I began by picking the magazine up on newsstands and finally ended up buying a subscription this spring. This is the 2014 summer issue and it is absolutely terrific: jam-packed full of beautiful photographs, interviews and articles (available on news stands now).

I had lots of questions about container gardening for Beckie, so let's dive right in:

A page spread from GardenMaking's special Container Gardening Issue

Q. Can you give me a few tips on how to go about selecting the best container?

A. The options available for containers can certainly be a bit mind-boggling! In terms of design, I think it is good to take a few cues from your house, other structures in the garden and the garden's overall design. But before you get to caught up in choosing the perfect container style and finish, I suggest that you consider two qualities- does the container you're considering allow for good drainage and is it the appropriate size? 

Big containers usually require less daily attention, because they need less frequent watering. They also hold more soil, which helps provide more insulation to your plant's roots in extremes of heat and cold. Small containers can serve a purpose too. Just be prepared to provide them more frequent attention.

A sea of pink Geraniums at a local nursery

Q. I have always added gravel to the bottom of my pots. GardenMaking's special container issue advises just the opposite. Why is that?

A. It is a commonly held belief that placing gravel or broken pot shards over the drainage holes helps to improve drainage, but we hold that just the opposite is true. Both gravel and shards take up valuable space where roots can grow and adds a lot of weight to the container.

Unless a piece of water-permeable landscape cloth is placed over the drainage hole, soil filters down and fills the spaces between the pieces of shard or gravel negating any improvement in drainage.

Instead, I suggest you cut a square of plastic window screen netting larger than the diameter of the drainage hole and place it in the bottom of the pot, over the opening. The piece of screen both keeps the soil in the pot, and allows the water to drain freely.

A page spread from GardenMaking's special Container Gardening Issue

Q. What can I do to give my newly planted containers a great start?

A. Once you have your containers potted up, water them with a transplanter fertilizer to help promote the growth of new roots. If possible, keep them in a shady spot for a day or two before moving them into their permanent location in the garden. If your annuals are leggy, pinch off their tops to force the plants to produce more flower buds and branches.

Q. Can you please give me a few tips on watering my containers?

A. Plants prefer lukewarm water. A jolt of cold water on a hot day can actually damage leaves and roots. It is also important to remember that tap water contains chlorine. If you are using water from the tap, fill your watering cans in advance to give the chlorine a chance to dissipate into the air. An even better solution is to collect rainfall to water your containers.

Also, keep in mind that on very hot days plant may flag in the afternoon, not because they need water, but because they are heat stressed. At these times, if the soil feels moist, wait until the end of the day to see if the plants perk up before reaching for the hose.

I recommend that you avoid watering at night, when moisture on leaves is an invitation for plant fungi to spread their spores.

Mulch your container plantings, as you would your flowerbeds, to help them to maintain moisture.

One last tip: If you are going away for a few days, move as many containers as possible to the coolest, shadiest spot in your yard and place them close together. This slows evaporation, and makes it handier for whomever comes to water.

Martha Washington Geraniums

Q. I am inspired by your special container issue to try my hand at making an alpine container garden. Can you give me a few tips to get me started?

I find that natural materials and wide, shallow containers work best for the miniature landscape of alpine plants. If you want to make your own free-form container Jennifer, I suggest you use hypertufa, which is a mixture of Portland cement, perlite or vermiculite and peat moss.

Then choose a variety of cushion and mat-forming plants, and space them in the container so their dainty attributes can be appreciated. Alpines like well-drained soil, so I recommend that you use a mix of two parts potting soil and one part coarse, gritty sand. Fill your container to the rim and mound it slightly in the centre. This will prevent water from collecting around the crowns of your plants.

Once you get your alpines are planted, mulch the exposed soil with a layer of course sand or pea gravel. Be sure to monitor water carefully-alpines need moisture, but detest soggy conditions. You'll find that true alpines grow slowly, so you shouldn't need to fertiize them more than once or twice a year.

They are very hardy plants, but you may find Jennifer, that your homemade container may need some protection from the freeze-thaw cycles of our Canadian winters.

Q. I love to mix some borderline hardy plants and perennials into my containers. How can I best store these containers over the winter?

A. Jennifer, I have three options to suggest:

Option 1: If the container is large, able to withstand the elements, and if the plants are at least one zone hardier than your area, the likelihood of overwintering your plants outdoors is high. If you can though, it is not a bad idea to move them to an area outdoors that is protected from winter sun and wind. It is also critical to throughly water your containers prior to freezing temperatures, and again in March and April, when they are most prone to thawing and drying out.

Option 2: Move any borderline hardy plants into an unheated garage or shed to increase the survival odds. The plant won't need light because it's dormant, but you should check on it every couple of months to make sure it isn't bone dry. Don't overwater though, as this could cause the plant to rot or break dormancy. When growth resumes in the spring, gradually reintroduce the plant to normal growing conditions outdoors.

Option 3: Find an area where you can sink the plant and its pot into the ground, so the roots will be better insulated (a veggie garden often has unused space in the fall). Then cover the plant with two or three inches of a winter mulch like shredded bark or leaves. In spring, remove the mulch and lift out the container.

Coleus

Q. How can I best overwinter plants like geraniums and coleus indoors?

A. It is important to start a reverse hardening off process before plants get accustomed to cool fall nights; otherwise they'll struggle with the change in temperature, as well as the different light and humidity levels.

A week or two before the nights start to cool, begin by bringing the plants indoors at night to gradually acclimatize them to lower light conditions and humidity levels. Cut back large plants by two-thirds to make them more manageable, and if desired, treat them with insecticidal soap to discourage pests from hitchhiking indoors.

Put your plants in a cool room with plenty of light. Water them when the soil dries out, and don't fertilize them until late winter.

If you would like to win a copy of GardenMaking magazine’s special “Container Gardening” issue, as well as a copy of their latest issue (Summer 2014, see above), please leave a comment below. If you are not a blogger, and would still like a chance to win, please feel free to leave a brief comment on the Three Dogs in a Garden Facebook page. The contest is open to everyone and will remain open for the next 7 days. Winner to be announced shortly thereafter.

More information and Links:

Garden Making Magazine home page.

About Beckie Fox:

After completing studies in journalism at Michigan State University, Beckie Fox worked as editor for a community newspaper in Etobicoke, Ontario. She then moved on to work as a freelance copy editor for Canadian Living, editing craft and food stories for the magazine. 

Beckie studied horticulture through the University of Guelph and has taught gardening courses at George Brown College and the Toronto Botanical Gardens. An interest in container gardening evolved into a book in 2002: The Potted Garden: Creating a Great Container Garden. 

Presently, Beckie Fox is editor-in-chief and co-owner of GardenMaking magazine. 

She gardens in Niagara-on-the-Lake, ON.