Your exact choice of planter is always very much a question of personal taste but the right scale and shape are of the utmost importance for creating a pleasurable effect.
Size: A planter with a sizeable quantity of growing medium will dry out less quickly than a smaller planter; it will also be capable of sustaining larger, more vigorous plants. As a general rule, planters with a diameter smaller than twenty three cm really should not be used for warm dry situations. A number of vases and urns which are extremely attractively shaped and proportioned have a soil capacity and planting area which are relatively small. Always make sure they'll give adequate depth of soil, or compost to accommodate plant root systems both in the middle and at the edge of the planter. 10 cm is only just sufficient to ensure adequate root area for small edging plants.
It is best also to consider carefully before choosing planters with narrow mouths, as despite their overall volume these offer only a very confined area for planting. To some extent this difficulty can be overcome by grouping several planters together to produce a bolder display.
Stability Always try to find planters with large or heavy bases to provide stability, particularly where there is to, be regular traffic of people.
At planting most plants used are going to be quite small. Always allow sufficient space to accommodate the plants when they are fully grown.
Weight: Some containers, especially stone ones can be very heavy to pick up and move although this is a bonus for stability. Such planters are not easily brought home in the car. Some planters are made in sections but even their separate parts can be heavy and awkward to transport.
Drainage: For drainage there should be one large hole or several smaller openings in the base of your planter.
Style: Modern designs will usually be out of place in old surroundings, however the converse is not necessarily the case.
Materials: Planters made in natural materials will normally look best, but will be more expensive to acquire, particularly if they're hand crafted or sculptured. Ease of maintenance: When siting a planter take into consideration ease of access to facilitate maintenance. For instance, it must be possible to reach window boxes for watering particularly if the windows do not open at the bottom. If you plan to site a hanging basket over an entrance, keep in mind the nuisance of dripping water. Situations exposed to continuous sun light can lead to rapid drying out and wind could cause damage to plants.
Designs: If several planters are to be used the group normally looks better if they are similar in design, or made from a similar material. Conversely, totally different kinds of planters are usually acceptable, positioned apart and separated by more permanent plantings. There'll of course be no problem if dissimilar planters are planted with a covering of trailing plants.
Stone, clay & lead containers.
Stone
Sculptural stone containers with ornamentation sculpted by hand are extremely effective but may be costly as well as being very heavy to move. Some are ornately decorated, but often the simpler shapes and styles suit small to medium-sized gardens best. There is little point in buying a stone container with an elaborate relief design if the carving will be obscured by the plant.
Clay and terracotta
Clay and terracotta pots can be plain or ornamented. An unglazed terracotta pot kept outdoors all year needs to be frost-proofed. Heavily glazed ones are frost-resistant and more water-retentive. Some smaller pots have deep saucers to act as short-term reservoirs.
Lead
lt continues to be possible to buy containers in traditional styles made from lead. These are heavy and expensive but tremendously long lasting. They will look well in most settings.
Concrete
Very large containers made from concrete with various finishes of exposed aggregate are suitable for forecourts of large buildings. If they are to be planted for seasonal effect, it is wise to use individual, smaller planters that fit inside them: these may be made up beforehand, so the planting can be removed and replenished without difficulty. Concrete and reconstituted stone are also used for smaller urns and troughs, and when well designed can seem like sculpted stone.
Plastic and glass fibre
Gardeners shouldn't discount the simulated stone planters produced from glass fibre or plastic well planted these may be very effective. They're light weight and easy to transport when empty; they are also much less costly. Some can be partially filled with sand for stability. This is best best done in situ.
Glass fibre is extremely durable and can simulate a variety of natural materials very realistically. This is also true of plastic, but plastic can deteriorate rather badly, faded by sunlight and battered by the weather, so check the quality very carefully.
Containers in natural wood look good in most situations and can be obtained in a variety of designs. Before purchase, check the planters for soundness of manufacture. Pay particular attention to the quality of the wood, checking for signs of potential splintering or warping and that the metal bands are firmly fixed.
Barrels and tubs
Properly coopered barrels are now more difficult to obtain than they once were, and increasingly expensive. However, garden centres sell wooden planters that serve well enough and can provide years of service.
The circular type of barrel suits most situations: square or triangular planters, fit well into corners. Half-barrels are extremely popular and of pleasing proportions. A few have integral handles to make lifting and moving easy. Some others have ornate tops, largely obscured once planted. Barrels are sometimes cut lengthways and mounted on wooden feet to create a type of cradle providing a long planting area that is good for bold, relatively permanent displays.
Painting and varnishing
The wood of a coopered planter should be sound in its natural state, however the external surface of other planters is best either varnished, or treated with a clear wood preservative, or painted. There is much to be said for keeping the wood its natural colour. lf you paint it, repainting at regular intervals will likely be necessary. Paint the metal bands also. The colour is a matter of choice but should naturally, tone with its surroundings.
Storing
lf unplanted planters are are going to be stored for any length of time. It's worth keeping them wet: when the individual slats dry out they contract and fall apart. Keep empty planters outside in a cool, shady position and regularly soak or submerge them in water.