Secrets to successful container gardening
Container gardening is growing in popularity faster than people can move into highrise condos in Toronto.
And it isn’t just balcony gardeners who are planting up virtually everything that will hold soil. Patios, decks, front doors and walkways are enhanced with containers full of colour and food plants everywhere.
So what are the secrets to growing plants successfully in containers? Here they are: 1. Choose the right container. Whatever you choose to plant in, make sure it has adequate drainage. Water should move through the soil and out the hole in the bottom of the container efficiently. If plants sit in water they rot, unless they are water plants, which belong in a pond.
Where containers are concerned, the greater the soil mass, the better the performance of the plants. This is why I do not recommend the small 10-inch hanging baskets that are so tempting. Large hangers, that are at least 14 inches in diameter, are so much better. Potting up geraniums in your uncle’s old boots might be cute, but even his feet are not big enough to create a cavity for soil to sustain plant life very well. A half-barrel-sized container is much better. And no one wears half-barrels on their feet. 2. Choose the plants for the location of the container. If your container is in full, blazing sun, plant sun-loving plants in it. This is more important in containers than it is in the garden, as the strength of the sun intensifies “off the ground.”
Look for dwarf zinnias, asparagus fern (a member of the lily family), petunias, million bells, scabiosa, lobelia and the list goes on. On the other hand, perennial hosta makes a great containerized plant in the shade or partial shade. And with a little care, it will come back each year. As will many other perennials. 3. Choose quality soil. Remove last year’s soil from your containers and spread it in your garden, where earthworms will pull it down and incorporate it into the rest of the soil. If you live in a condo, ask management if you can place the old soil in the condo garden. Just don’t leave it in the container two years in a row. That soil is tired; the nutrients in it are used up, but it is fine to spread over an established garden.
When looking for container mix, buy quality: you really get what you pay for. Choose a brand you trust. Quality soil drains well, is full of nutrients that help boost plant life throughout the growing season, and some mixes feature water-retaining abilities that reduce the frequency of water applications. 4. Water with the rain. Use a rain barrel to hold rain water and apply this to your container plants throughout the season. This is how I water all my containers and I believe it makes a world of difference. Rain water is soft, is charged with oxygen, and it is almost always warm. If only plants could talk, they would tell us this is their preference. “I hate cold showers!” you would hear them roar.
Allow container soil to dry to the touch between watering applications. When water evaporates or transpires through a plant, the space it takes in the soil is replaced with oxygen-rich air. All plants love this. Some plants, like geraniums, prefer to get quite dry, but never bone dry. In time, you will learn what works best for you in your environment. 5. Fertilize. There are many options where “plant food” is concerned. The bottom line is that containerized plants demand more nutrients than “garden bound” plants, as their roots are limited by the walls of the container and the volume of soil at their roots. From several metres away, I can usually tell if a plant is hungry, especially late in the season when nutrients in the container mix have been used up. Yellowing leaves, poorly performing flowers and a look of general malaise takes over a hungry plant. There are many fertilizers on the market, some synthetic and others natural, including a new organic that lasts all season long called ProMix Multi-Purpose Garden Fertilizer.
What is more important than all of this, if you want the best show of colour or crop of tomatoes from your containers? Your choice of plants, of course. Next week, in this column, I will review my favourite plants for containers, both flowering and for eating. Stay tuned. Mark Cullen is an expert gardener, Order of Canada recipient, author and broadcaster. Get his free monthly newsletter at markcullen.com. Look for his new bestseller, The New Canadian Garden, published by Dundurn Press. Follow him on Twitter @MarkCullen4 and Facebook.