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Tips for success in container gardening

A container growing lettuce, cucumber, swiss chard and a trellis supporting a tomato plant. Photo credit: Minter Country Garden [PNG Merlin Archive]
A container growing lettuce, cucumber, swiss chard and a trellis supporting a tomato plant. Photo credit: Minter Country Garden [PNG Merlin Archive]

By Brian Minter

I would venture to say well over 60 per cent of our food and colour plants grown at home are planted in containers, but, unfortunately, many with varying degrees of success. We all have great expectations when we begin our container gardening, but when ‘things happen’ to limit that success, we are rightfully disappointed.

Over the years, I’ve learned a few tricks that can make all the difference in growing both your own food and colour in containers.

A huge factor is placing containers in a location that is sunny between the hours of 10 a.m. and 4 p.m. Those hours provide the most and the best quality of light and heat that are so essential to sun-loving plants. If you don’t get sun during this critical time frame, all is not lost — you simply need to grow food and colour plants that perform in shade. For example, all leafy vegetables, like lettuce, swiss chard and arugula, as well as radishes, most Asian vegetables and most herbs will do fine. In the colour department, impatiens, begonias, lobelias and fuchsias love the shade.

In case you weren’t aware, size does matter. I’m always concerned when I see lots of plants stuffed in small containers. It’s a maintenance nightmare. Larger containers accommodate a critical mass of soil that can provide more natural nutrients and dries out far less frequently. The minimum measurements of round or square containers should be 18-20 inches across and 18 inches deep. Rectangular containers should measure at least 18 inches by three feet by 18-inches deep.

One issue with larger containers is the practice of partly filling them with rocks, Styrofoam or whatever else people think will allow them to use less soil. It’s not a great strategy for your plants. At a recent Plant-a-Row meeting in New Westminster, B.C., one of the best surplus food programs in our country, Egan Davis, chief educator at the UBC Botanical Garden, gave a rather scientific explanation for why filling our containers with inert material isn’t good for the growing process.

Always use high-quality soil. All the time and effort it takes to grow what you love can go sideways with poor soil. Many lightweight soil blends are available to help keep the weight of your container down, while at the same time providing for all your plants’ needs and making watering and feeding less onerous. I use professional soil mixes like the Sunshine or the Pro Mix blends that include the beneficial mycorrhizae fungi. Both brands, as well as many other companies’ products, have OMRI certified organic blends.

Use what works for you, but don’t cheap out on less-expensive, low quality blends. Top soils are meant for use in the garden, while container blends are designed specifically for pots. Many folks also add organic matter to professional mixes with great success.

Nutrients are far more critical in containers than in garden beds. Every time you water your container, you’re leaching out goodness, so it needs to be regularly replenished. Today, we have many organic soil nutrients, but they actually have a low NPK (nitrogen, phosphorus, potash) analysis. They work efficiently but slowly.

The trick to feeding your plants is to produce not only good vegetative growth (i.e. foliage), but also vegetables, fruits and flowers. If I see too much vegetative growth happening and very few fruits or flowers, I use Alaska Morbloom 0-10-10 to slow down the green growth and speed up the process of veggie, fruit and flower production. Another approach to feeding, especially today when many of us are so busy, is to use a balanced slow-release fertilizer, like Osmocote 14-14-14, that will provide constant feeding for three or more months.

Despite all your good efforts, watering may prove to be a challenge. Watering depends largely on the weather. When it’s hot and sunny, you need to check at least once or even twice each day to determine if your plants need watering. On the other hand, overwatering is the worst-case scenario. When the soil stays wet, it pushes out the oxygen and can quickly begin to rot your plants’ roots.

Watering early in the day is best because your soil will be moist during the time when the stressful heat is on your plants. Always wait until the soil is on the dry side or just moist, and then water thoroughly. If you can water only in the evening, do it gingerly, and water just the soil, keeping all moisture off the leaves to prevent or minimize any disease issues.

If you’re a little unsure whether to water, remember that a little too dry is far better than too wet. If you can lift your container, you can easily tell if it needs watering. As a rule of thumb, if it feels light, it’s dry. If it feels heavy, it has lots of water. If your pot is too heavy to lift, watch for the slightest sign of wilting that would indicate dryness and the need for moisture.

Innovation is also important in container growing. Think ‘outside the box,’ so to speak, because you can grow beyond your container. I love using trellises in my containers. Once solidly secured, they’re ideal for all climbing plants such as peas, beans, cucumbers and squash. Anything that allows vines to grow upward where it’s higher, drier and gets more sunlight is a bonus. This is also true of colour plants like sweet peas, nasturtiums and the ever-popular thunbergia (the black-eyed Susan vine). I also set my containers up on pedestals to allow many of the plants to trail over the edges. By employing both these methods you can double or triple your production and colour.

As for plants in the colour department, almost anything goes. Virtually all annuals are well-suited for containers but choose plants that will perform throughout the summer and well into fall. The Proven Winners line and the Dummen Orange varieties are great. Coleus are now becoming superstars both in sun and shade containers.

Copyright Postmedia Network Inc., 2019

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