What Type of Soil Do Zinnias Grow Best In?

Site Requirements

• Most soil types result in healthy zinnia plants. These flowers aren't fussy about soil pH and will thrive in most established garden beds. The site must receive six or more hours of daily sunlight to ensure best flowering and lush growth. The soil should drain well so it doesn't retain too much moisture and become soggy or waterlogged. Avoid beds with hard, packed soil or those in low-lying areas where water tends to accumulate on or near the soil surface.

Soil Quality

• The quality of the soil is determined by its texture and how well it drains. Loose, crumbly soil that drains well without completely drying provides the best soil option for zinnias. This soil type is rich in organic matter. Working compost into the soil before you plant further improves it for healthy growth. Compost can also improve clay soil and sandy soil so it drains better and develops a better texture. Spread 2 to 4 inches of compost over the soil and mix it in with the top 6 to 8 inches of the soil for best results. The compost will also supply some nutrients to the site.

Fertilization

• Applying a slow-release, balanced fertilizer before you plant supplies the initial nutrients the zinnias need. For example, sprinkle 1 tablespoon of a 10-10-10 blend fertilizer over each square foot of garden bed. Mix the fertilizer with the top 3 inches of soil before you plant. A second application made three weeks after planting replenishes the nutrients in the soil for the remainder of the season. When applying fertilizer around existing plants, sprinkle it at least 6 inches away from the base of the zinnias and water immediately after application so the nutrients soak into the soil.

Soil Moisture

• Although soil that's rich in organic matter retains moisture well without becoming soggy, it's still necessary to irrigate the zinnia bed regularly. Zinnias grow best when the soil remains evenly moist and isn't allowed to dry out completely. Watering deeply once or twice a week so the top 6 inches of soil is moistened during irrigation supplies sufficient moisture. A 2-inch layer of mulch placed over the soil and around the plants further helps retain the moisture in the soil.