Gardening in Pots & Containers
A few well-placed pots can transform an area. They breathe life into bare spaces, add interest to the garden and give a welcome focal point to entrances, ends of pathways, alongside seats and soften stark walls. They are the perfect solution for today’s lifestyle gardener who may not have a conventional garden, but wants to add atmosphere to a patio, deck or balcony.
Vegetables and many fruits can also be grown very successfully in containers being an ideal solution where space is limited.
Choose a style that suits your house and garden. Stay consistent with complementary styles and materials.
Available in standard or classical styles. Many plastic pots tend to fade or become brittle and break. Some newer more expensive styles have UV protection enabling them to last for several years. Some new terracotta imitation is better.
Available in various shapes and sizes. These are usually made from macrocarpa or tanalised pine timber. Old wine barrels are used for rustic effect. Containers made from heavy 40mm thick timber will last many years but when made from lighter timber or wine barrels, the life may be only 6 – 10 years.
Available in a large range of sizes/styles. Terracotta has a rustic but tidy appearance which goes with most décor. Simple styles are and relatively inexpensive. Whilst larger sizes seem expensive, they do make a bold feature and can be good value. Light weight or low temperature fired pots are likely to crack and break in frost conditions.
Also available in a large range of sizes/styles, and a range of colours to complement any decor.
Concrete or Crushed Marble
Mostly moulded into classical shapes.
Creative Containers for a bit of fun. Boots, wheelbarrows, cream cans, chimney pots, baskets, broken pots, and hollow logs, can all be used for growing plants.
Saucers & Stands
Saucers are helpful in keeping patio areas clean. A stand or spacer under the pot ensures free drainage from the pot.
The Potting Mix:
It is important to use a good free draining potting mix. A good mix is especially formulated for this purpose, using mostly composted pine bark or peat, often mixed with a little sand, or pumice. The potting mix also contains a controlled slow release fertiliser which varies according to the brand, purpose, and price. Some mixes may contain a fertiliser that only lasts 3 months while others may contain a fertiliser that lasts 9 months and occasionally more – read the label. The better mixes also contain water storage granules for extra water holding capacity and a wetting agent which ensures easy and complete wetting of the mix when watered. If the potting mix brand you have does not include these ingredients then add extra fertiliser and Saturaid as described below under feeding and watering.
Most potting mixes contain sufficient controlled release fertiliser for 3 to 9 months, (depending on the brand and type – check the label) thereafter feeding is required on a regular basis.
Plants growing in pots have a restricted root system confined to the pot size which is much smaller than if they were in the soil. Hence plants are reliant on the food and water in the limited amount of potting mix. Therefore it is necessary to feed regularly.
The preferred fertilisers are either:
1. A resin coated controlled release fertiliser which was probably originally used in the potting mix, such as Nutricote, Osmocote, Acticote. These are available in 3 month, 6 month and 9 month release times.
2. Novatec Premium is a new technology fertiliser with nitrogen inhibitor which is excellent for container plants, providing 3 – 4 months feeding. A little more care is required in that heavy applications could harm small sensitive plants. Generally however it is very safe and much less expensive than the resin coated products above. For established woody, semi-permanent container plants three applications a year in Sept, Dec, and March provide excellent results.
3. Soluble or liquid fertilisers (Thrive Soluble, Thrive Liquid, Nitrosol, Fast Food, Powerfeed, Miracle Gro) applied with a watering can, are suitable but require an application every 2 weeks, which is often inconvenient and is more expensive.
Avoid using organic or animal manures as these products undergo a breakdown process first into ammonia, and then into the nitrate form required for plant uptake. Frequently, an ammonia build up occurs which is toxic to the plant. In addition, organic and animal manures are low in potassium leading to plants lacking thrift and disease resistance.
Seaweed products are not fertilisers as such in that they contain only minute amounts of the major elements required for plant growth. They do however contain some trace elements and natural plant growth hormones – auxins, gibberellins, and cytokinnins which stimulate the plant providing the mix, food and water are all in order.
Probably the most important factor with container gardening is water. The amount and frequency of watering depends on the size of the pot relative to the size of the plant, the particular plant species, and the position of the pot.
Potted plants dry out quickly and will usually require daily watering in summer and once every 2 or 3 days in spring and autumn. Plants such as tomatoes with a gigh water demand will require watering twice a day in mid- summer. For hand watering, use a soft spray nozzle on the hose and be sure the potting mix is thoroughly watered. A system of irrigation drippers or weeper hose which can also be automated, is effective for watering pots.
A major problem that occurs, is that when the mix in the pot becomes dry, it repels water. You may well have applied 3 or 4 litres of water to the pot but 95% of it immediately runs out the bottom. Applying a wetting agent such as Saturaid every 3 months ensures that the applied water soaks into the potting mix and is therefore available to the plant.
Some gardeners also add water storage granules to increase water holding capacity of the mix, but the benefits of this are limited.
Plants that can be grown in pots or containers
Most plants can be grown in pots, but large fast growing trees and shrubs are not really suited and will deteriorate in just a two or three years.
Annuals are straight forward and pots are normally replanted twice a year – seasonally.
Perennials are also relatively simple, but the life attractive life of the plant is usually only a couple of years – a little more with some plants.
Woody shrubs may have a life of 5 to 20 years depending on the plant and the care and maintenance provided.
A problem often encountered is when a gardener has planted directly into a terracotta pot and five or ten years later, when the plant has passed useful life, it is impossible to get the old plant out of the pot without destroying both plant and pot.
This problem can be avoided by planting into a pot liner – a plastic pot of a size that sits comfortably inside the terracotta or ceramic pot.
Another benefit of this is that if the plant has an off season and is bare or unattractive for some months (eg. Hydrangea), the plant in the plastic liner pot, can be taken away and a more attractive seasonal plant also in a plastic liner pot, inserted in it’s place.
Pots of 40cm diameter or 30 litres capacity are ideal for many vegetables – lettuce, spinach, dwarf beans, carrots, cucumbers, beetroot, silver beet, and tomatoes (some may require supports)
Larger containers or half wine barrels are useful for fruits such as citrus, feijoa, blueberries, raspberries, boysenberries, passionfuit, figs, and dwarf apples.
Planting the ornamental pot /container.
Match the container to the plant – complimentary or contrasting colours, balance - the size and shape of the pot- with the size and shape of the plant.
Make sure the container you choose has drainage holes in the bottom. A layer of course pumice or stones in the bottom will assist drainage. Fill container with a recommended potting mix, taking care not to overfill. Leave a 1 to 2cm space before top of pot so that water does not run off instead of into the pot. Water the plant thoroughly before planting. Plant up, tamp down firmly and water.
Mulching the surface of the pot with pebbles adds a decorative finish as well as helping to retain moisture.
Plants for containers.
Most plants can be grown in containers, however, some varieties are more suitable than others. The following plant lists are a guide to getting started. There are many more suitable varieties available. Ask your garden centre staff for further help.
Mass plant single colours for impact (eg pansies, petunias).
When putting together a mixed container of annuals and perennials choose well grown plants and plant closely for an instant effect.
Individual shrubs can be under planted with mounding or trailing plants
Shrubs for long term large containers
Azalea; Camelia; Citrus; Conifer; Corokia; Dwarf Flax; Hebe; Hydrangea; Pieris; Maple; Meulenbechia; Pittosporum - Golf Ball; Patio Roses; Poor Knights Lily; Succulants; Syzygium (eugenia); Viburnum – Eve Price; Westringia; Yucca
Plants for medium containers
Begonia; Calabrichoa; Bubblegum petunia; Dwarf Dahlia; Dwarf Flax; Federation Daisies; Fuchsia; Geranium; Herbs; Hosta; Lavender; Patio Rose; Pelargonium; Sun Impatiens
Annuals / perennials for any containers
Alyssum; Alstroemeria; Impatiens; Lobelia; Marigolds; Pansies; Petunia’ Geranium; Polyanthus; Snap dragon; Viola; Hosta;
Bulbs for medium containers
Bluebells; Daffodils; Freesias’ Hyacinths; Tulips
Plants for small containers
Cyclamen; Hyacinths; Ipheion; Rhodohypoxis; Viola; Succulents; Zephyr flower.
Garden information supplied by Bill Brett, horticulturist, Garden Retail Success Ltd