Complete Seed-Starting Guide: Annual Flowers from Phlox to Portulaca

Starting annuals from seed saves money and unlocks endless variety. Here's a comprehensive system for success, tailored to your Massachusetts east-facing yard (morning sun, afternoon shade).

Your Purchased Seeds: Light Reality Check

Phlox drummondii, Calendula, Portulaca, Convolvulus—all are full-sun plants. With only morning sun, they'll flower less and grow leggier. Consider adding shade-tolerant begonias and impatiens for the shadier spots.

Recommended High-Performance Annuals

• Salvia 'Flare' — 18-inch red spikes, sun-loving
• Celosia 'Fresh Look' — Vibrant all summer, minimal deadheading
• Profusion Zinnias — Mildew-resistant, no deadheading needed, multiple colors
• Oklahoma Mix Zinnias — Tall, great for back borders
• Marigolds, Sunflowers, Petunias — Reliable sun performers
• Begonia, Snapdragon, Coleus, Impatiens — Best for shade

Seed-Starting System (20+ Years Refined)

Timing

Start 6–8 weeks before last frost. Check packets for specifics.

Sowing Technique

• Never sow deeper than 2× seed diameter
• Tiny seeds: press onto surface, barely cover
• Water from bottom to avoid displacement

Light & Environment

• 14 hours daily under fluorescent lights (1 cool + 1 warm white bulb = full spectrum)
• Lights 3 inches above seedlings—raise as they grow
• 8 hours darkness for respiration
• Remove humidity domes at first sprout to prevent damping-off

Soil & Nutrition

• Sterile mix: vermiculite, perlite, sphagnum moss only
• After 2nd true leaves: half-strength fish/seaweed emulsion
• Avoid chemical fertilizers on seedlings

Essential Supplies Checklist

Seed trays, cell packs, peat pots, humidity domes, sterile mix, heat mat, 48-inch light system, gro-lux bulbs, hand seeder, plant markers, fish emulsion, mister.

Resources

Park Seed catalog (free), Nancy Bubel's New Seed-Starters Handbook, extension guides from Missouri and GardenGuides.com.

With this system, you'll grow 500+ strong seedlings annually—just like the pros.