Planting and Care Guide for Popular Annual Flowers

These annuals prefer mostly sunny locations. Deadhead to prolong bloom.

Annual Mums

In hot climates, choose a spot with afternoon shade. Sow seeds outdoors after weather warms for summer/fall bloom (mild winters: sow fall for spring/summer). Also available as nursery plants. Not fussy about soil. Space 8″ apart. Water deeply and often in porous soils, less in heavy soils. Feed 2–3 times per season.

Cosmos

Sow seeds in open ground spring to summer, or transplant from cell-packs, 4″ pots, 1-gallon cans. Yellow cosmos easiest from nursery plants. Flower best in poor, sandy soil; rich soil and fertilizer reduce blooms. Space 12–18″. Tolerate some aridity, but water weekly for best bloom, especially in hot valleys.

Dahlias

Provide light afternoon shade in hottest areas. Plant tubers in spring after soil warms and frost danger passes. Dig 1-ft holes in loose, organic-rich loam. Space large kinds 4–5 ft, small 1–2 ft. Drive stake; place tuber horizontally 2″ from stake, eye pointing toward it. Cover with 3″ soil, water well. As shoots grow, gradually fill hole. Water regularly after shoots emerge. Dahlias in compost-enriched soil rarely need extra fertilizer.

Marigolds

Full sun. Easy from seed—sprout in days in warm soil. Or use nursery flats, cell-packs, 4″ pots. Slugs/snails love young foliage; use traps or horticultural diatomaceous earth around planting.

Sunflowers

Sow seeds in spring. If using nursery plants, space 8–12″ in compost-amended soil. After true leaves appear, water deeply weekly. Fertilize once during active growth with controlled-release fertilizer. Large-flowered types need rich soil and lots of water.