PREFERRED SOIL pH: Neutral to slightly alkaline
PREFERRED SOIL TYPE: Fertile, well-drained
PREFERRED LIGHT: Sun to partial shade
ATTRIBUTES: Gray-green leaves; white, lilac, pink, red, or yellow spires of rosebud-like, fragrant flowers
SEASON OF INTEREST: Spring to early summer; fall; frost-free winters
FAVORITES: Trisomic Giant Imperial Mix; Giant Excelsior for tall spires; Brilliant for heat tolerance
QUIRKS: Needs cool nights to flower well
GOOD NEIGHBORS: Iris, poppy, primrose, pansy, rose
WHERE IT GROWS BEST: Cool climate; fertile, neutral to slightly alkaline soil; sun or partial shade
POTENTIAL PROBLEMS: Rot, powdery mildew; aphids, flea beetles
CRITTER RESISTANCE: Good
SOURCE: Bedding plants, seeds
DIMENSIONS: 2-3 ft (0.6-1 m) tall, 1 ft (0.3 m) wide
Stock in the Landscape
Stocks are quick starters. They sprout in a week and rush to blossom, usually within 10 weeks of sowing, providing glorious color and fragrance before other plants set their first flower buds. When spring temperatures hover around 50°F (10°C) at night and remain below 65°F (18°C) during the day, stocks grow steadily, sending up 18-30 in (45.7-76.2 cm) tall flower spires. Each is thick with rosette-shaped single or double blossoms in white, lilac, purple, peach, pink, red, or yellow. Double stocks also boast a spicy scent.
Spring-sown plants won't last in hot weather, and fall-sown plants are felled by freezing temperatures. So plant stocks where you need a dash of color before later-blooming perennials perform, or combine them with other early bloomers, such as pansies and primroses. In Zone 9, stocks can also be grown as bedding plants and as cut-flower annuals for filling vases throughout the winter.
Getting Started with Stock Plants
You can buy seedlings, but stocks are easily grown from seeds. Sow indoors 6 weeks before your last frost, or before the onset of cool fall weather. The seeds need light to germinate, so sprinkle them on the surface of moistened commercial seed-starting soil. Put the container on a well-lighted windowsill or under fluorescent lights. Keep the soil moist and between 50°-60°F (10°-16°C) for 1-2 weeks to ensure germination.
A certain percentage of stocks grown from seed have single flowers, but you can pull them out and discard them after sprouting. The leaves of single stocks are a darker green than those of doubles. Transplant light green seedlings into 2 in (5.1 cm) pots when their second pair of mature leaves develops, and transplant to the garden when conditions are favorable. You can also sow seeds outdoors, when the weather is cool, in moist, fertile, neutral to slightly alkaline soil in sun or partial shade.
For fragrant, early blossoms in a range of colors, grow Trisomic Giant Imperial Mix. Heat-tolerant Brilliant is for areas where spring is quickly followed by hot summer temperatures. If cool weather lasts in your area, go for Excelsior, also known as Giant Excelsior, which has carmine red, white, midblue, or pink blooms.
Growing Stock Flowers
The biggest problem for stocks is heat, which causes plants to become dwarfed and reduces flowering. To prevent it, plant early. As a precaution against bacterial rot, a disease that fells seedlings, soak the seeds in hot water 130°F (54°C) for 10 minutes before sowing. In damp, humid conditions, a fungal disease called powdery mildew can disfigure leaves. Control it by clipping and disposing affected leaves, and prevent it by spacing plants far enough apart for good air circulation. Sap-sucking insects, such as aphids and flea beetles may feed on leaves. Knock them off with a strong spray of water from a hose, or apply insectici-dal soap according to label directions.