How to Grow Large California Poppies

Purchase only fresh, good quality poppy seeds, as old seeds may not germinate or may produce substandard plants.

Grow California poppies by planting seeds directly by seed in your garden, as poppies don't transplant well. Plant seeds as soon as the ground dries enough to be worked in early spring. Alternatively, plant California poppy seeds in autumn in places where winter temperatures stay above freezing.

Prepare the soil in a garden spot where the poppies will be in full sunlight. Don't plant poppies in soggy, waterlogged soil. Spade the garden soil to a depth of 6 to 8 inches. Pick rocks, dirt clods and clumps of weeds from the soil, then smooth the soil with your rake. Dig 2 to 3 inches of compost into the soil if your garden soil tends to remain moist and water doesn't drain quickly after a rainfall. Poppies require no fertilizer, but will benefit from 2 to 3 inches of manure mixed into clay or other poor soils.

Scatter the California poppy seeds evenly over the soil, then cover them with a light dusting of fine soil. The soil covering should be no more than 1/16th inch deep. Don't bury them completely, as covering the tiny seeds blocks the sunlight and may prevent germination. Poppy seeds germinate in about two weeks when temperatures are between 60 and 70 degrees Fahrenheit.

Water the California poppy seeds lightly after planting. Use a watering can or a hose and spray attachment, being careful to avoid washing the tiny poppy seeds from the soil. Keep the soil moist until the seeds germinate. After that, California poppies are drought tolerant and require water only during extended periods of hot, dry weather.

Thin California poppies when the seedlings are 1 to 2 inches tall. Remove the weakest seedlings, allowing 10 to 12 inches of space between each plant. Allowing plenty of growing space results in bigger blooms.

Deadhead, or pinch off fading poppy blooms; removing wilted flowers causes the plant to continue producing blooms instead of using energy to generate seeds. Leave a few flowers in place at the end of summer if you want the poppies to reseed for blooming next spring.