Late Summer Flower Garden Tasks: Disbudding, Deadheading, Feeding, and Propagation

Disbudding Chrysanthemums

Finish disbudding early-flowering chrysanthemums; start on late-flowering varieties by late summer end for mid-autumn+ blooms.

Deadheading

Continue removing spent flowers from annuals, bedding plants, pelargoniums for immaculate displays. Herbaceous perennial deadheading is less critical but often done anyway when cutting for the house.

Feeding

Liquid-feed all potted chrysanthemums, sweet peas (if treated), and greenhouse plants as in mid-summer. Light-soil lawns: one half-strength feed early in late summer, no later — late lush growth = soft plants vulnerable to winter.

Staking Freesias

Newly planted freesia corms need stakes now for later floppy leaves/stems. Seed-grown freesias have finished leaf growth — no further foliage training needed. If well-watered, lightly shaded, not overheated, they'll start flowering stems in early autumn.

Resting Hippeastrums

Most hippeastrums end growth now — stop watering completely; lay pots on sides under staging. But modern hybrids with evergreen ancestry may retain leaves — don't feed, keep just moist to slow metabolism.

Increasing: Pelargonium Cuttings

Take pelargonium cuttings anytime in late summer — regals early, zonals late. Regals: floppier, fewer larger trumpet flowers. Zonals: dark leaf zone, tight clusters of small flowers — popularly 'geraniums'.

Good cutting: no flowers/buds, short internodes (5–7.5 cm / 2–3 in between leaf joints, not 10–12.5 cm), stem not hardening but not soft/sappy. Ivy-leaved and scented-leaved types also root easily — any summer time works.

Cuttings ~11 cm (4½ in), cut cleanly below leaf joint, remove lowest leaves. 3–4 around edge of 9 cm (3½ in) pot of sandy compost, cover with clear plastic bag, in cold frame outdoors or shaded propagator in greenhouse (no bag). Watch water needs.

Routine Work

Mowing, watering, weeding, compost-making continue but smaller scale than mid-summer. Outdoor watering may cease — then weeding/mowing become more demanding.

Pest and Disease Treatment

Capsids, leafminer, greenfly, caterpillars less troublesome, but final precautionary spray on chrysanthemum/dahlia (capsid/leafminer) and cinerarias (leafminer) advised. Watch greenhouse for whitefly, red spider mite, mealybug.

Earwigs = main problem, especially on dahlias. Best trap: flowerpots with straw/paper inverted on stakes. Earwigs feed at night, hide by day — check traps daily, destroy catches. Chemical sprays on flowers (main targets) often do more damage than insects.

Mildew = rapid-spreading fungus in late summer on Michaelmas daisies, chrysanthemums, others. Resistant varieties exist. Powdery white patches on leaves, stems, buds — kills leaves, malforms flowers, stops stem growth. Favors dry, warm weather; plants with dry roots hit hardest. Stuffy, poor ventilation encourages spread. Remove affected leaves ASAP, spray remainder with fungicide, or use preventive systemic.