Picture a cobbled mediterranean street with pots of bright red geraniums up the narrow steps of a white painted house, melons cradled in there supports on a city balcony or the grandeur of stone pots in an ornate formal garden. Pots and containers have been making gardens flexible and accessible to both the space deprived and the wealthy and can add a spark of colour that catches the eye in the shade of an urban garden.
Why use a container or pot? Containers allow the use of space which would otherwise be barren. Containers allow the use and movement of seasonal colour and eye catching highlights. Pots can provide a controlled environment, for example using ericaceous compost in a garden with unsuitable soil type. Pots allow for the protection of plants from the cold and the wet in winter.
Choosing your pot or container.
Pots and containers are used both indoors and outdoors and come in a variety of shapes and sizes. There are a great variety of pots available for purchase or you can be creative and recycle or upcycle an unwanted container to suit your budget. Sometimes it can be a bit overwhelming to know what you need.
What do you want to do with your pot or container? How multi-purpose does it need to be? Is it a pot that will be a focus throughout the year? Consider what you will be planting in it and for how long? Seasonal bulbs, summer annuals, fruit and veg, trees and herbs, are they hardy or tender and needing winter protection?
Terracotta is a traditional style of pot. It is good for cacti and succulents as it is porous and therefore not only holds water but it dries out quite quickly so plants do not get waterlogged. Terracotta pots may also be glazed to reduce water evaporation. Look out for whether they are labelled frost proof especially when planting hardy trees and bushes or overwintering bulbs and flowers. Even if they suffer damage they can live on as crocks as drainage for other pots.
Plastic is a barrier to sideways moisture movement and is reusable. It is lighter than terracotta but will eventually degrade in the sunlight.
Wooden containers can be created from recycled timber or bought. Wood is a longer term option but will eventually rot and decay - giving homes to insects as it does so. To reduce water damage line it with waterproof material. Wooden containers can be heavy so take care siting them to best effect before filling with compost.
Plants in metal containers conduct both the heat and the cold so in winter it may mean the plants are more susceptible to frost damage.
Grow Bags and reuse of compost bags. Grow Bags may not be deep enough for tomatoes so would a deep pot be better instead? My daughter uses her tomato grow bag on edge to give a deeper soil depth for deep planting her tomatoes. I’ve tried one shallow grow bag on top of another to allow the tomatoes a deeper root run, but it’s quite tricky to set up as you need to create access for the roots between the two. You can also use mushroom cartons or buy halos and other adaptations to put on top of grow bags in order to increase the soil round the tomato stem and to support canes.
Larger pots are better at providing more space for compost and therefore are less prone to drying out but if you need to move your pots regularly then consider the size and subsequent weight especially with moist compost in. Pots should not overwhelm a plant but be just a bit bigger than the rootball. So when you pot on do so in small stages.
When growing something tall or top heavy then the weight of a pot can be increased by putting bricks or gravel in the bottom of the pot, underneath the compost.
Create the habitat
Use appropriate compost for the type of planting you are doing. To make the compost more free draining add grit where needed. Bulbs, alpines and succulents need a more free draining compost. Home compost can be mixed with garden soil or a proprietary compost for vegetables and bedding plants.
Mature plants such as bushes, fruit trees and perennials may also need a more soil based compost which you can either make at home or buy. Compost such as John Innes No 3 have more mineral content which the plant will need for long term health.
Acid loving plants such as azaleas, camellias and heathers need an ericaceous compost.
Water and watering needs
Pots and containers will need watering and feeding more often as roots cannot go deeper in search of moisture and the nutrients in the compost will be used up over time. Place crocks at the bottom to cover large drainage holes and allow water to still drain. If you can raise the pot up on blocks or feet to allow drainage for plants that don’t like to be waterlogged.
Water retaining gels can improve uptake of water as well as increasing the time between regular watering; these are not needed for cacti, succulents and most alpines as these need drier conditions and hate being moist for long.
Use saucers in the summer and if you are away on holiday so that water is kept accessible for the plant to take up if the compost has become too dry. Remove saucers in winter to enable water to drain in the cooler wetter weather and so to prevent roots rotting.
A surface mulch of compost, bark or decorative stone prevents the evaporation of moisture and reduces the number of weeds, including moss. Line hanging baskets with old compost bags helps to reduce the retention and wastage of water.If you are away a lot the fewer pots the better unless you can group them in a cooler shady area where they will support one another, be easier to water by your friend or relative and lose less water through evaporation.
Repotting of long term containers
As plants grow and the year progresses then the nutrients in the compost will decline, the compost itself will become more compacted and more moisture retentive. For long term containers many will need repotting every few years into fresh compost. An annual removal of a couple of inches of compost and replenishing with fresh can help but once a plant is pot bound pot it on into the next size of pot. Once the plant is in the maximum preferred pot then the whole of the compost may need replenishing every few years. At this time tree roots can be lightly pruned before repotting.
Suitable plants for tubs and containers include:
Alpines, cacti and succulents
Bulbs both summer and spring
Dwarf varieties of trees, fruit trees on dwarf rootstocks; varieties of fruit bushes bred for container growing.
Vegetables such as salads, courgettes, tomatoes, potatoes, carrots etc.
Herbs
Plants that will take over if their roots are not kept in check eg mint and horseradish
Mediterranean plants such as rosemary, oregano and sage.
Decorative flowers and foliage such as bedding plants.
Indoor containers can also be useful for houseplants, salad crops, microgreens and herbs. Use containers where and if you need them and enjoy the benefits they bring to both wellbeing and wildlife.