From our perspective, the single most critical element in our container environment is drainage. Our roots absolutely despise sitting in waterlogged soil. Soggy conditions lead to root rot, a fatal condition that suffocates us and prevents us from taking up essential nutrients. Therefore, the soil medium you provide must be well-aerated and free-draining. A standard garden soil is too dense and compact for container life; it will hold excessive moisture and ultimately lead to our demise. We require a potting mix specifically designed for containers, which is typically lightweight and formulated to prevent compaction.
We thrive in a loose, moderately fertile, and well-draining potting mix. The perfect blend for us would be a quality all-purpose potting soil as a base. To this, we greatly appreciate the addition of coarse materials like perlite or coarse horticultural sand. A ratio of about three parts potting soil to one part perlite is ideal. The perlite creates essential air pockets within the soil, ensuring oxygen reaches our root zone and allowing excess water to drain away quickly after watering. This loose structure also makes it easy for our roots to spread and establish themselves throughout the container, giving us a strong anchor and access to resources.
While we are not heavy feeders, we do require some nutrients to support our vigorous blooming from summer through fall. A moderately fertile soil is perfect. We prefer a soil pH that is neutral to slightly acidic, ranging from about 6.0 to 7.0. Most quality potting mixes fall within this range. When you plant us, you can incorporate a slow-release, balanced fertilizer (such as a 10-10-10 formula) into the soil mix. This will provide a steady supply of nutrients throughout our main growing season. Over-fertilizing, especially with high-nitrogen formulas, will encourage excessive leafy growth at the expense of our iconic golden-yellow flowers with dark brown centers.
While drainage is paramount, the soil must also have the capacity to retain some moisture to sustain us between waterings. A small amount of organic matter, such as compost or coco coir, is beneficial for this. Coco coir is an excellent amendment as it absorbs water well but also helps maintain soil structure and aeration. The goal is a soil that feels like a wrung-out sponge after watering—moist but not dripping wet. This balance allows our roots to access water without drowning. You can check this by feeling the soil a few inches below the surface; water us deeply only when that level begins to feel dry.
