Seed poppy requires full sun and thrives in a dry, warm climate. It grows well in most Utah soils provided they are fertile, finely textured, and friable.
Poppies prefer a site in the garden that receives full sun and fertile soils. Soil should be prepared in the fall to allow for early spring planting. Before planting, determine fertilizer needs with a soil test, then follow the recommendations given with the report. If fertilizer applications are warranted, work the fertilizer into the top 6 inches of soil. If you apply compost, use no more than 1 inch of well-composted organic matter per 100 square feet of garden area.
Poppy seeds are extremely small (100,000+ seeds per ounce). Seeds should be sown sparingly in shallow furrows or surface broadcast. To prevent over seeding, mix seed with fine sand and broadcasted mixture. Poppy seeds need light to germinate. Cover seed with no more than 1/8 inch of soil. Seeds also germinated better when exposed to freezing and thawing conditions; therefore, sow seeds either in late fall or very early spring. Plant growth and development is slow, and seed maturation takes up to 5 months, so early sowing is essential. Seeds germinate slowly requiring 4 weeks to emerge in cool weather and 2 weeks if the weather is warmer.
Seedlings are cold hardy and plants form larger blossoms and seed heads when grown in cool weather. Several weeks after seedling establishment but before seedlings are 6 inches tall, thin plants to 4 or 6 inches apart. Thinning can be avoided by using transplants in place of direct seeding; however, poppies do not transplant well. If transplants are used, germinate and grow plants at 60°F. Grow seedlings for 4-6 weeks and plant out around the last frost date for the area. Transplant carefully to minimize damage the roots while planting.
After seeding or transplanting, keep the seed bed moist until seedling emerge or transplants are established. Various methods of irrigation may be used as long as the seeds are not washed away before they germinate and become established. After final thinning, water needs are low about one inch per week, depending on weather conditions.
In addition to fertilizers applied at soil preparation, seed yield increases when plants are fertilized with additional nitrogen. Sidedress poppy plants with 1-2 tablespoons of 21-0-0 per 10 ft. of row after thinning and before flowering to maintain vigorous growth.