Greetings from the plant kingdom. We, the Black-eyed Susans (Rudbeckia hirta), are a resilient and sun-worshipping bunch. While we are known for our adaptability, providing us with our ideal soil conditions allows us to thrive, not just survive, producing our most vibrant blooms and healthiest foliage. Here is our detailed perspective on the matter.
Above all else, our roots demand soil that does not hold excess water. We are highly susceptible to root rot and other fungal diseases that flourish in waterlogged conditions. Our root systems are designed to seek out moisture in well-aerated earth, not to sit in saturated, oxygen-deprived mud. Therefore, the absolute best soil for us is one that allows water to percolate through it freely. Sandy loam is often ideal, as its structure provides a perfect balance of drainage and moisture retention. If your garden soil is heavy clay, you must amend it generously with compost, coarse sand, or other organic matter to open it up and improve its drainage capacity.
We prefer a soil texture that is loose and crumbly, what humans often refer to as loamy. This type of soil is a balanced mixture of sand, silt, and clay particles. It is easy for our young, tender roots to push through and establish a strong foundation. Furthermore, loamy soil is naturally well-aerated, providing the crucial oxygen our roots need for respiration and nutrient uptake. Compacted or heavy soil stifles our growth, leading to stunted plants and lackluster flowering. A simple test is to pick up a handful of moist soil; if it holds its shape loosely but crumbles easily when poked, it is perfect for us.
Contrary to what you might think, we do not require, or even desire, extremely rich, heavily fertilized soil. In fact, an overabundance of nitrogen, in particular, will encourage an excess of floppy green foliage at the expense of our famous golden-yellow flowers. We are quite content in soil of moderate to low fertility. The key is to ensure the soil has a healthy population of beneficial microbes and organic matter. Incorporating a modest amount of compost or well-rotted manure at planting time provides a gentle, slow-release source of nutrients and improves the overall soil structure, which benefits us far more than synthetic fertilizers.
When it comes to soil pH, we are not particularly fussy. We can perform adequately in a range from slightly acidic to slightly alkaline (approximately 6.0 to 7.5 on the pH scale). However, our optimal performance is typically observed in a neutral pH, right around 6.8 to 7.0. At this neutral range, the widest array of essential soil nutrients remains available for our roots to absorb. For most gardeners, the native soil pH is acceptable, and extensive amendments are rarely necessary for our successful cultivation.
