From our perspective, the single most critical factor for our survival and flourishing is that our roots are never left sitting in water. We African Daisies (Osteospermum spp.) hail from the well-drained, often rocky and sandy slopes of South Africa. Our root systems are simply not adapted to heavy, waterlogged clay soils. In such conditions, our roots suffocate from a lack of oxygen and quickly succumb to rot, a death sentence for us. Therefore, the absolute best soil type you can provide is one that is loose, airy, and allows water to percolate through it rapidly after watering or a rain.
While we demand excellent drainage, we also appreciate a modest amount of organic matter to sustain our vibrant blooms. The perfect soil for us feels like a crumbly, light, and slightly gritty mix. A high-quality potting mix designed for containers or raised beds is an excellent start. For in-ground gardens, we thrive when you amend native soil. If your soil is heavy clay, you must amend it generously. We recommend a mixture of:
- Coarse Sand or Grit: This is the key ingredient to replicate our native conditions, dramatically improving drainage and aeration.
- Compost or Well-Rotted Manure: This component provides a slow-release source of essential nutrients and helps the soil retain just enough moisture for our roots to access it without becoming soggy.
- Perlite or Pumice: These inorganic additives further prevent soil compaction and ensure the root zone remains oxygenated.
We are not overly fussy about soil pH, but we perform our best in a range between 5.5 and 7.0 (slightly acidic to neutral). This pH range allows our root systems to most effectively uptake the micronutrients from the soil that are vital for producing our large, daisy-like flowers. In highly alkaline soils, we may show signs of nutrient deficiencies, such as yellowing leaves (chlorosis), particularly in iron. You can easily test your soil's pH with a home test kit. If you need to lower the pH slightly, incorporating peat moss or an acidifying fertilizer can help.
We are not heavy feeders. In fact, overly rich, nitrogen-heavy soil will encourage an abundance of floppy green foliage at the expense of our beautiful flowers. The organic compost you mixed into the soil at planting will provide a good foundation. To support our prolific blooming from spring until fall, a supplemental feeding is beneficial. We prefer a balanced, water-soluble fertilizer applied at half-strength every 4-6 weeks during the growing season, or a light application of a slow-release fertilizer at the beginning of the season.
Once planted, a layer of light, organic mulch around our base is greatly appreciated. A mulch of shredded bark, straw, or pine needles helps regulate soil temperature, conserves moisture (reducing the frequency of your watering), and suppresses weeds that would compete with us for resources. Crucially, ensure the mulch is not piled directly against our stems, as this can create conditions for rot. A light, even layer is all we need to feel perfectly at home in your American garden.
