Planting in Containers

Planting in containers of all shapes and sizes has long been popular with gardeners but has probably grown in importance in recent years for a number of reasons. Garden Centres have certainly promoted it for people with small gardens, patios, balconies and courtyards as an easy way of bringing beauty and colour into our outdoor spaces, however small. It has been aided by the greater range of compact plants which are now available and the vast growth in the variety and affordability of containers. In the ornamental garden containers can be used for the whole range of plants from Alpines, Bedding, Bulbs, Cacti, Climbers, Conifers, Herbs, Roses, Shrubs and even small trees. In the edible garden vegetables, fruit bushes and fruit trees can all be successfully grown in suitable containers. Container plantings are also used as part of garden designs for a variety of purposes:- to provide focal points, to give dramatic effects even in small spaces, to soften hard landscaping, to brighten otherwise dull areas, to disguise unattractive features and to provide all year round displays. Containers are also useful in that they can provide plants with a soil that is not to be found in the garden eg. an acid (Ericaceous) soil for plants such as Rhododendrons, Azaleas and Camellias or a gritty, well-drained soil for Alpines and Cacti.

Containers literally come in all sorts of shapes, sizes and materials each with their own advantages and disadvantages. One house in our village has the path to the front door lined with planted up boots and shoes and there really is no limit to what can be used as long as they have some form of drainage holes. Most plants do not do well in waterlogged soil as they need both air and water around their roots. Terracotta pots are attractive when weathered, are reasonably priced and allow the compost to breathe but, unless they have been fired at a high temperature as most, if not all British pots have, they are not always frost resistant or proof. Plastic pots are generally low cost and are light and easy to handle but they have poor heat insulation, can become brittle with age and don’t weather attractively as other materials do. Concrete pots do have good heat insulation and weather well but are usually more expensive and certainly much heavier. Wooden containers look attractive and natural but eventually deteriorate, even if treated. Ceramic pots have probably seen the greatest increase in use over recent years as they are colourful, come in a vast range of shapes and sizes, are generally well priced and, because they are glazed, are reliably frost proof but they can be on the heavy side. Basically it is a case of “you pay the money and take the choice!” but I would say that it is worth trying to choose a container that “suits” the plant or plants which are to live in it. This is generally a matter of personal choice but there are a few guidelines which are worth keeping in mind. Getting the scale right is important so that the plant looks right in the container, not too small to be swamped by it and not too large that it cannot thrive or the whole thing becomes top heavy and blows over! Matching the colours of container and plants is also important, choosing either complementary colours such as red and orange or blue and green or, for a more striking arrangement, contrasting colours such as blue and orange or purple and yellow.

Once the container has been chosen the next stage is to decide on the best compost to use. Garden soil is not really suitable, certainly not on its own, as it is heavy, not usually rich enough in nutrients and becomes compacted and rather air less as a result of all the watering which pots require. There are so many composts on the market these days that choosing the right one can be a bit of a challenge. However, there are really only two basic types of compost to decide between. Firstly, there are the “Soil-less” composts which are peat based, peat reduced or peat free. I prefer the latter two as our peat bogs are being depleted at an alarming rate and in my view are best left alone for the special plants and creatures which inhabit them. Soil-less composts are light and best, therefore, for hanging baskets, window boxes and seasonal pots. The second group are the “Soil-based” composts which are generally based on a formula devised in the 1930’s at the John Innes Horticultural Institute. John Innes was a London property developer and philanthropist who, on his death in 1904, left money  to establish a school for horticultural instruction. This became in 1910 the John Innes Horticultural Institute and since then has become a world leader in plant genetics and all things horticultural. In the 1930’s two of its gardener/scientists created the John Innes growing medium formulae which we still use today. The composts are a mixture of loam (the best sort of topsoil with a mixture of sand, silt and clay), grit, fertiliser and a small amount of peat .Basically the larger the JI number, the more fertiliser the mix contains. These soil-based composts are better for more permanent planting with Number 2 for Alpines and Herbs and Number 3 for the rest. This is because they retain their nutrients for longer, give firmer support to larger plants, have greater weight for pot stability and will still drain well in winter as long as there is grit or crocks in the base of the container.

The one disadvantage of planting in containers rather than the ground is that containers do need a little more care and attention. Firstly, they will need regular and frequent watering due to the fact that there is only a limited amount of compost in them and because rain, even if there is any, doesn’t penetrate very well into pots which are full of growth. In the summer this may mean every day and with hanging baskets more than once a day. This can be reduced a little by choosing compost with added moisture retaining materials or by adding water-retaining crystals to your compost before planting. Secondly, again because of the limited amount of compost and all the watering which needs to be done containers will need extra feeding to keep the plants at their best. The compost will contain enough food for the first month or so but after that a boost is required. One way is to add slow release granules to the compost at the time of planting or after the first month. Another way is to add a liquid feed to say 2 or 3 waterings a week, again starting at the end of the first month. At this point it is worth adding owner Christina’s advice on planting baskets and seasonal pots something which she has done thousands of times since opening the Old Railway Line garden centre with husband Mark over 25 years ago!  She would always say use the best compost you can buy and pack the plants in as closely as you can for really spectacular displays. Dead heading of spent flowers, unless they fall off easily like Petunia flowers, is also important as it will keep the container looking at its best and will also keep the plants flowering for longer as it stops them from setting seed at which point they would stop producing new flowers. It is also important to remove any weeds as soon as you see them and to be vigilant about pests and diseases so that they can be dealt with early before they become a real problem.

This is a great time of year to plant up your containers, particularly if you wish to use the tender bedding plants which can’t be planted out safely until the risk of frost is passed. The Old Railway has lots of bedding, compost and containers all available safely by Click and Collect.  You won’t regret having a go at container planting and you may, like me, eventually grow to enjoy the watering regime!

Next time I am going to have a look at Gardening in June, one of my favourite months, with some jobs that are best done in June and what plants are looking at their best.

Until then keep safe and well and good gardening!

Keith.