Guide to Container Gardening
Filling the Garden Container
John Innes pottingNo. 2 suits most plants, as do proprietary loam-based potting composts. (Choose John Innes No. 3 for permanent subjects such as trees and shrubs.) Ordinary garden is not recommended; it is not sterilized and may harbour weed spores, that can quickly demolish the contents of a pot. Renew compost in shallow garden containers annually.
If you wish to grow lime-hating plants such as, , and some heathers, use a lime-free compost such as John Innes acid compost or a proprietary peat-based compost.
When filling your garden containers with soil, first make sure that the drainage holes are not clogged.
Place crocks over the holes at the bottom of the garden container to ensure that they remain open, followed by a thick layer of washed pebbles or coarse gravel. This drainage layer should, ideally, occupy about one quarter of the container’s depth, but if you don’t want too much weight, a 5cm (2in) layer is usually adequate for a short-term planting.
To prevent soil being washed into the drainage layer, cover it with a sheet of hessian sacking or rag. Or, place a thin layer of turfs — grass side down — on top. Finally, fill with the potting compost to within about 2.5-5cm (1-2in) below the rim; firm gently.
Hanging baskets of the rigid plastic type are planted like any other container, but open wire baskets need different treatment and should be lined before planting
Planting Up the Garden Container
Water all plants a few hours before planting. Organize the planting scheme in your garden container by arranging the chosen plants on the surface of the soil. Put the largest in the centre or towards the back of the container, finishing off with dwarf or trailing types around the edges.
Once satisfied that the design is correct, set the plants to one side. Using a hand trowel, dig holes for the largest ones first. Knock them out of their pots one at a time and plant them slightly deeper in the garden container than in the original pot. Firm in well and water gently once all the plants are in place.
Where the planting is permanent or semi-permanent, a top layer of wood bark chippings, gravel or rock chippings can be sprinkled around the plants to improve the overall appearance and reduce moisture loss from the compost. A top layer of this kind also prevents soil surface capping where hard tap water is applied regularly. For temporary planting, mulching is unnecessary.
Garden Container Aftercare
A garden container will dry out quickly, so frequent watering is essential, especially when they are standing in full sun. Apply water to the soil — not over the leaves and flowers — preferably in the evening or early morning. Give enough water to moisten the soil thoroughly, then leave until the soil is almost dry before watering again — overwatering a garden container is as harmful as too little water. In hot spells, water may be needed twice a day.
For additional plant vigour, give a regular liquid feed every two weeks — never apply fertilizer to dry soil. Dead-head all plants regularly and stake and tie tall species as necessary.
Watch out for pests and diseases — dense plantings often encourage fungal diseases and many. Spray with a general-purpose insecticide and fungicide regularly. Sprinkle slug bait to control slugs and snails — also check around the rim of a tub for snails hiding during the daytime. Clear away fallen leaves and other debris from the soil to discourage fungal growth.
With permanent plantings, scrape off the top 5-7.5cm (2-3in) of soil every spring and replace with fresh potting compost. Check the securing brackets of garden containers such as window-boxes and hanging baskets at the same time, replacing if necessary.