The last of the spring flowering bulbs are still in bloom but now is the time to plant bulbs for a colourful summer display.
Gladioli. These are brilliant in the herbaceous border or dotted through shrubs. The long stems are excellent for cutting for flower arranging. They are best planted in groups of 8-10 keeping the corms about 8 cm (3 inches) apart.Dig a hole 15 cm (6 inches) deep. Spread a layer of sharp sand or grit in the base to prevent the corms rotting. The taller varieties will require staking.It is better to insert the supports at planting time or after growth has appeared. Providing they are not being grown for show, the dead flowers may be removed as they fade leaving the remainder to carry on the show.
Dahlias. Now that the risk of serious frost has passed dahlia tubers may be planted out. Those which have started to sprout should be planted a little deeper with the soil covering any growth. Spacing in the bed will depend on the variety with large growing decorative and cactus types needing 60-90 cm (24-36 inch) spacing. Make certain the canes or stakes used for support are not pushed through the fleshy tubers. Slugs and snails love the new growths, grazing them to ground level .Use traps or pellets to keep the numbers down and remove the bodies. The range of flower shapes and colours allows them to be used among shrubs, herbaceous borders or in the cutting bed for use indoors. Disbudding, leaving one flower bud per stem, results in enormous flowers with some of the decorative varieties growing to dinner plate size. Dahlias will continue to flower until the first frost blackens the leaves. They may then be lifted taking care not to damage the fleshy roots and dried off for winter storage.
Begonias. Starting the tubers off indoors in trays of moist peat speeds up the time to flowering. Set them the right way up with the rounded side down and the depressed side pointing up. The shoots are easily broken and need to be treated with care. Plant 10 cm (4 inches) deep, 30 cm (12 in ) apart in groups in the bed. They may be grown in large containers in a soil based compost for use on the patio.Shelter from wind is essential as the stems are brittle. Feed every week with half strength liquid tomato fertilizer. Remove diseased leaves before the botrytis spreads. In autumn lift the plants, remove the foliage and dry the tubers before storing them in a frost proof area for the winter.