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Maintaining your container

Watering

Under- or over-watering is the number one reason why plants in containers fail. If you don’t have the facilities and time to keep your containers watered then you should reconsider whether you actually want to have them or not. To complicate matters further, you’ll find that different plants, container types and locations require different watering frequencies. As a general guide, containers need watering once a day, unless they have had significant rainfall (and aren’t placed in rain shadows) that day. In hot, dry spells baskets and small pots should be watered twice a day.

But don’t lose heart! If you have the time or money to spend, there are plenty of ways in which you can make watering a bit easier:

Electronic automated watering systems

These are a godsend, particularly while you’re away on holiday. The best kind are those with rain gauges so you can balance your watering against rainfall (although remember that containers in rain shadows won’t receive much of a watering from rain), but these are rather expensive, so the models which simply act as an ‘on/off’ timer fitted to your tap are a good starting point. Make sure you experiment with the watering frequency and duration for at least a week or so, monitoring the moisture levels within the containers regularly, so you get the right balance to suit all your plants.

Saucers

Placing saucers or trays under the containers will provide a reservoir of water for the plants. Ensure that the water isn’t too deep, as this can waterlog the soil, and remove the saucer in the winter when more drainage is required.

Grouping containers

Putting your containers into a few large groups can help ease the burden of watering in two ways. Firstly, it’s quicker to water a bunch of containers in one spot, rather than walking round to lots of individual pots. Secondly, grouping plants together creates a more humid atmosphere which will reduce the amount of water lost through transpiration.

Reaching baskets

Watering baskets can be a physical, as well as a time, problem. However, there are many solutions available to reaching high baskets and other wall hung containers. These range from sophisticated pulley systems allowing you to lower baskets, to simpler solutions such as watering them with a water bottle rather than a heavy watering can. Automated systems, as discussed above, usually come with fittings to allow the automatic watering of baskets.

Please see our information on planting your containers for ideas on how to maximise water retention and find out which plants to choose for drought tolerance.

Deadheading

Containers are most often used to provide colour to an otherwise dull spot, therefore you want to do everything you can to maintain the flower display as long as possible. Deadheading does exactly that – it removes spent flowers and prevents the plant producing seed, so the plant keeps on flowering in order to produce seed. Once a plant has produced seed it puts all its energy into this and stops flowering. Many flowers can be pinched off by hand but where the plant flowers in clusters and just one or two flowers are dead, you might find it easier to use nail scissors to remove the spent blooms. Where the flowers are growing on a single, long flower stalk, you can remove the whole stalk down to the joint (this is best done with secateurs) to keep the plant neat.

While deadheading, you can also cut back leggy stems to a node to keep them more compact, or to stop vigorous plants swamping more delicate specimens. Any other pruning should be done according to the individual plant’s requirements.

Feeding

Assuming you added a slow release fertiliser to your compost when planting up your container, this should provide enough food for the lifespan of temporary displays. However, if you have permanent plants in your containers then you will need to top up their food supply periodically.

Unless your plants are showing indications of a nutrient deficiency, you should aim to give them a balanced feed, containing nitrogen, potassium and phosphorous. You may wish to give them a fertiliser with a higher proportion of potassium in their flowering season to encourage the production of more flowers (specialist tomato feeds are a good choice for this purpose).

Ideally you should aim to use an inorganic fertiliser, since organic ones require microorganisms in the compost to break them down and make them available to your plant – as you have created a closed, relatively sterile environment in your container, it might be some time before the nutrients are broken down sufficiently for your plant to use them. Inorganic fertilisers can be slow release, eg granules, which can be added when refreshing your compost (see below), liquid feed (ideal as a ‘pick me up’ for neglected plants) or fertilisers which work within automated watering systems to provide a regular dose of feed.

Managing pests, diseases and disorders

Plants growing in containers are vulnerable to most of the pests, diseases and disorders which affect plants growing in the soil. However, there are some which are more prevalent with container grown plants, including:

Maintaining good hygiene and maintenance regimes around plants, and monitoring them regularly for signs of problems, is the best way to reduce the risk of these problems.

Changing the compost

Temporary plantings will last quite happily for one season in the same compost, however permanent plantings will need some compost maintenance every year. On an annual basis refresh the compost in the container by removing the top 5-10cm of compost (including any roots growing at that level) and replace it with fresh compost, including any fertiliser you want to add at that point.

Every few years the plant will need to be lifted from the pot and either moved onto a bigger container (if you want the plant to grow bigger) or re-planted in the same container with fresh compost and, if necessary, some of the roots and top growth trimmed back. You may find it quite difficult to remove large rootballs from the container. There is no easy solution to this! The best way tends to be to put the container on its side (protecting it underneath with a tarpaulin or cardboard if you’re concerned about it chipping) and using a lady spade (slimmer than normal spades) to lever the roots out. If necessary, the perimeter roots can be cut off using an old bread knife to slim down the root ball. Remember that if you remove roots you need to remove roughly the same proportion of top growth to keep the plant in balance.

You can then trim back any dead, damaged or diseased roots, tease the compost from between the roots, and re-plant it in fresh compost with slow release fertiliser granules mixed in. Keep the plant in a sheltered spot and water regularly for a couple of weeks afterwards to help it recover.

Removing temporary displays

It’s very easy to just bin annual and tender perennial plants from your temporary displays and buy new plants the following year. This is certainly one way of doing it. However, if you want to be more frugal, you can keep most plants going to use again the following year. There are plenty of different ways of doing this:

Remember to compost any plants which you no longer require, so long as they are not diseased.

Overwintering permanent displays

Even the most hardy plants will suffer in harsh winter conditions. Take appropriate measure to protect your containers against winter conditions, here are some examples:

  • Cover the containers with horticultural fleece or bubble wrap.
  • Move plants under cover or to a more sheltered place (eg next to a house wall).
  • Use foam insulation pipes (the type plumbers use to insulate household water pipes) to protect the stems of standards.
  • Ensure that you don’t overwater your plants in the winter and that the containers are draining well; waterlogging and freezing conditions are a deadly combination for your plants and pots.