Apart from selecting plants which form attractive combinations, it is essential that when bought they are sturdy, strong and healthy. It is false economy to buy cheap, inferior plants as they never recover to produce attractive displays. This is especially important with plants intended for planting in windowboxes and troughs – as well as tubs, pots, urns and hanging baskets – as the display is concentrated and a few inferior plants can spoil the design for several months.
Apart from buying healthy, floriferous and vigorous plants, there are a few general factors to consider:
- Avoid tall plants, especially those intended for winter displays. Buffeting autumn and winter winds soon devastate displays with tall conifers, especially in window boxes secured to first-floor window sills. However, tall plants can be used on wind-protected patios.
- To create the ‘body’ of the displays, use compact plants, but avoid creating a flat, uninteresting surface. Some displays have random, varied heights, while others either peak in the middle or, if in a trough positioned with one of its ends towards a corner, have a slightly triangular outline. Most displays, however, have an irregular ‘natural’ shape.
SMALL conifers are usually bought in 6-7.5 cm/2½ – 3in wide pots. Check that their roots are not constricted through neglect. Also, ensure the compost is momist and the plants do not have bare areas of foliage.
EARLY summer-flowering pot plants, such as Cinerarias (Senecio cruentus), are sold in 7.5 – 13cm/ 3-5in wide pots. Complete with their pots they are placed in window boxes to create colour early in the year.
VARIEGATED ivies are also sold in small pots. Usually, there are three plants growing in the same pot, as this creates a bushy and more saleable plant quicker than when only one plant is used.
DO NOT buy inferior plants as they never recover and may leave bare gaps in windowboxes and troughs, spoiling the overall display. Do not buy thin, spindly plants, an indication that they have been grown too close together and neglected. Neither buy small plants in relatively large pots, nor large plants in small pots.
WHEN buying flowering plants in pots for placing in window boxes to create temporary colour, avoid those that are in full bloom when bought. Such plants will not create a long display. Instead, buy those with masses of flower buds that are just showing colour. Check that the flower buds are evenly arranged around the plant, and not just on one of its sides.
- Trailing and cascading plants are essential to clothe the fronts and sides of window boxes and troughs. Use a mixture of those that trail nearly vertically, as well as cascading types which create the impression that the container is larger than it really is.
- Use foliage plants that trail and cascade, in addition to flowering types , as they tend to create a sense of permanency.
- Variegated trailing plants, such as small leaved ivies and the Variegated Ground Ivy (Glechoma hederacea ‘Variegata’), create colour in winter, spring and summer arrangements. Small-leaved ivies used indoors can be moved outdoors into containers, but do this in spring so that they have the entire summer in which to become accustomed to the some-what cooler conditions. They are then better able to survive winters outdoors than if put directly outside in autumn.
Check all plants to ensure they are free from pests and diseases. Small plans are easily checked, but with large ones look both above and under their leaves. Also, check around soft buds and shoot tips. Pests such as greenfly (aphids) breed prolifically if not noticed.