Weather and the Gardener
If the summer has been dry August is the time of great soil moisture deficits, accompanied inevitably by bans on the use of hosepipes and similar restrictions which beset a gardener as the authorities try to eke out their inadequate water supplies. Under such circumstances water has to be used with care in a garden. Certain plants or crops have to be given priority, so it is wise to find out the critical stages in their growth when plentiful soil moisture is important. Limited water supplies should not be rationed to all plants, but given to those which will benefit the most.
Trees and Shrubs
Those in flower in August include forms of catalpa (Indian bean tree), eucryphia, magnolia, buddleia (butterfly bush), calluna, erica and daboecia (heaths and heathers), caryopteris, ceanothus, clerodendrum, deutzia, fuschia, genista (broom), hibiscus (tree hollyhock), hydrangea, hypericum (St John's wort), lavandula (lavender), eycesteria formosa, myrtus (myrtle), olearia (daisy bush), potentilla (cinquefoil), rosa (rose), yucca, clematis, jasminum (jasmine), lonicera (honeysuckle), passiflora (passion flower) and polygonum (Russion vine).
Pruning
Lightly clip lavandula (lavender) to remove dead flower heads. Also trim cytisus (broom) and helianthemum (rock rose).
Rose Care
Remove flowers as they fade. Cease general rose feeding at the end of the month of August and apply potash at 60g per sq metre (2ox per sq yard) to help ripen the shoots for winter.
New plants from Old
Use trimmed unflowered lavender shoots as cuttings, removing the lower leaves and inserting a sandy soil in a sheltered position. Take cuttings of new side shoots of heathers if required. All should be ready for final planting in 12-15 months time.
Layer low growing shoots of jasmine, rhododendron, viburnum and cotinus (smoke tree) by nicking underneath the stem with a knife and pegging down with a U-shaped wire into a peaty soil near the parent plants. Sever the plant when rooted.
Flowers
Gather stems and flower heads of blue eryngium (sea holly) and just opening blooms of catananche (cupid's dart) for drying and creating winter flower arrangements; do the same with Physalis franchetii (Chinese lantern).
Divide mat-forming, small leaved plants that flowered earlier, such as waldsteinia and armeria. Larger leaved plants must be left until September. Water in thoroughly and spread moist peat among their crowns to reduce moisture loss from the root area.
Remove spent flowers from seedling perennials flowering precociously, to direct energy to strong vegetative growth and better flowers the following year.
Alpines
Take a look round your local garden centre or pay a vist to a rock garden specialist to select plants for flowering in late summer and autumn when there is little colour about. Kinds to choose include scarlet, fuschia-flowered Zauschneria californica, August, September; Solidago 'Tom Thumb', golden yellow, September, October, and pinkish red spiked Polygonum affine 'Darjeeling Red', September, October.
Take heeled cuttings of Genista lydia, G. kewensis, Thymus nitidus and other shrubby plants; make them about 5cm (2in) long, remove the lower leaves, dip in hormone rooting compound, then insert to half their length in a rooting medium of equal parts sharp sand and peat.
Container-grown conifers are not difficult to establish and there are many forms to give your rock garden character. Some of the most interesting and shapely are golden Thuya orientalis aurea nana, yellow thread-leaved Chamaecyparis filifera aurea nana, and the blue-green carpeting Juniperus sabina 'Tamariscifolia'.
Bulbs
Plant in groups of seven or nine, bulbs of the October flowering Sternbergia lutea, a giant golden crocus-like plant for a sheltered position in light shade. Set the following bulbs 5cm (2in) deep; autumn flowering crocuses such as the violet blue C. Cancellatus cilicius, lilac C. goulimyi, rosy lilac C. sativus cashmerianus, rich violet C. speciosus; daffodils for frocing into early flower for Christmas, such as variety 'Paper White'; and Colchicum autumnale (naked ladies) which produces its large crocus-like heads in October, but without foliage.
Vegetables
In favoured situations make a last sowing of lettuce, specially a mildew-resitant variety, such as Avondefiance. Make a second sowing of spring cabbge in the first week of August. Finally, make a further sowing of salad onions for use over winter and in spring.
Now is a good time to dow large onions for overwintering. These are a realtively new crop, with varieties mainly of Japanese origin. Sow on a piece of well-drained soil which has been cleared of a crop for several weeks and prepared so that moisture has come back near to the soil surface. Germination is required to start quickly after seed sowing, and for this good moisture is essential. The emergence of onions is much more rapid that in the cold conditions of spring, now taking perhaps as little as eight days.
Celery Care
Now is the time to earth-up maincrop celery, but kep soil out of the centres of plants. Make sure that the stems on outside rows of self-blanching celery beds are covered. Individual plants within the bed blanch each other by excluding light. Unless either a sheet of black polythene or wooden planks are put close up to the plants round the outside of the bed, the sticks will remain green in the light and be less attractive. Applications of nitrogen to self-blanching celery are important.