When I moved into my new home in Brisbane, I brought two containers. One held my furniture, the other potted plants. As I unpacked my house I also unpacked my garden. Being portable, potted plants are an ideal solution for gardeners who rent or who have no soil. In my current home I have a simple system for growing and displaying my potted plants. First of all, I only keep pots that two people can move by trolley. For my outdoor displays, I have placed decorative ceramic pots in spots where a permanent display will catch the eye. In each ceramic pot I place a plant growing in a smaller pot, filling in the gap between the two pots with bark and using it to conceal the inner pot. This filling insulates the roots from too much summer heat which can stunt growth.
Each season I change these outdoor display plants. In winter, for example, plants that I keep in the shade during summer are moved out into sunnier locations, where they can benefit from the weaker sunshine and shorter days. My houseplants generally spend most of their life outside. I bring them indoors for a week or two when they’re looking their best. This system allows me to match my plants to seasonal growing conditions, while adding variety and interest both indoors and out.
The four materials commonly used to make plant containers are plastic, terracotta, ceramic and concrete. Concrete that’s painted or sealed with a glaze has the same function as a ceramic pot, it’s just heavier. Unsealed concrete behaves like terracotta.
This is by far the most common material. Lightweight and cheap, plastic pots come in all sizes and colours, and cope with rough handling. They retain moisture longer than terracotta, a bonus for moisture-loving plants. Plastic is flexible, so expanding root systems take longer to split the sides and, if needed, a pot can be cut open to salvage a plant. When buying, check that the pots have functioning drainage holes. Also, some plastics are UV-stabilised, which extends their life as they don’t break down so quickly in sunlight. But store empties in shade as they’ll last longer.
This is an attractive but heavy material. The extra cost is offset by durability. Terracotta is porous, so moisture evaporates through the sides, a plus when you’re growing plants that need excellent drainage. Terracotta bowls are ideal for growing shallow-rooted plants such as bromeliads, and their weight can be an advantage in exposed locations, reducing the risk of toppling.
These pots are decorative and almost as heavy as terracotta. They are fired to a higher temperature than terracotta and are usually glazed. They’re the most expensive of all, but are useful because they come in the widest variety of shapes and colours. Tall, slender ceramic pots are very fashionable. When filled with potting mix, it can be difficult for shallow-rooted plants, such as begonias and bromeliads, to reach the bottom. Often, when the upper layer has fully dried and the plant needs watering, the bottom layer of mix is still wet, becoming progressively acidic and anaerobic. To counteract this, work some charcoal into the bottom layer. Ceramic pots retain moisture like plastic and, when handled with care, can be as durable as terracotta.
Not all potting mixes are equal. Ones to trust display the Australian Standard or NASAA Certified Organic logo. Other mixes may be cheaper, but quality varies. All potting mixes are bark-based with added gravel, sand and wetting agents or water-saving crystals, and some mixes have added fertiliser. Bark gradually breaks down, losing volume, so plants may slump in their pots, some requiring repotting more than once a year. When dry, bark is also hard to remoisten by watering.
Plunge pots in a bucket or sink of water for half an hour to rewet. If you are growing plants with fussy needs, choose a customised potting mix. For example, there are mixes for cacti and succulents. Potting mixes containing wetting agents or water crystals should only be used for moisture-loving plants, especially if used in plastic or ceramic pots. Wet conditions encourage root rot.
Routine care helps avoid most problems. Here’s a simple checklist. Fertiliser Liquid fertiliser is the safest way to feed potted plants as there is less chance of over-fertilising, which can lead to growth problems and even root death. Look for fertilisers formulated for potted plants and only apply when the plants are actively growing and nutrients can help. Avoid feeding in very hot conditions.
Water Allow plants to go slightly dry, without wilting, in between each drink. Use your finger or a moisture meter to check, or learn to judge from the pot’s weight. Saucers are useful for preventing balcony and windowsill plants dripping on your neighbour below, or spoiling furniture and floor surfaces. However, water impedes drainage, which can lead to growth problems and suffocate the roots, causing death by root rot. Empty saucers after watering. Mulching the tops of potted plants helps insulate roots from extreme temperatures and conserves moisture. Mulches such as decorative pebbles can look stylish, while organic mulches such as sugarcane improve growing conditions. Try using groundcover plants as living mulches. If you use plants with similar watering needs, they’ll happily coexist.
Repotting It is good to repot plants every year or two in early spring. Check how quickly the rootballs fill the pots and repot into slightly larger containers before they become congested. Many pots have a classic straight-sided vase shape because it makes it easier to remove an intact rootball when repotting plants. Long, slender pots make this difficult to do without causing damage. Try driving a broom handle through the drainage hole to help release the rootball.
When dense root masses fill pots with curved sides, cut off any roots growing through the drainage holes. Then try plunging the pot vigorously into a tub of water, or use a hose to blast the potting mix off the roots. If you’re lucky, you’ll get the pot-bound plant out and won’t have to resort to breaking your pot.
The most successful, easy-care and long-lived potted plants are those with either fibrous or compact root systems. These plants make good companions, growing well together in the same pots.
Use low-growing ferns, such as delicate maidenhair, as a groundcover to enhance the enduring flower displays of begonias.
The compact succulent groundcovers, such as blue chalksticks (Senecio serpens) and carrion flower (Huernia and Stapelia), contrast well with the richly coloured and patterned cycads. In areas with high rainfall, grow succulents in pots to stop root rot. Create mini gardens using dwarf agave, echeveria, rebutia and bold impala lily (Adenium obesum).
Combine for a lush effect of flowers and foliage.
Try growing a combination of a dwarf peach, apple or lemon underplanted with golden marjoram, variegated society garlic or mint for both utility and beauty.
To buy pot plants and other products for your garden head to Garden Express
Want more? Check out: How to grow pot plants.
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