Commercial bird seed is a mixture of various grains and oilseeds packaged for avian consumption, not for cultivation. Despite this intended use, the seeds are generally viable, meaning a significant portion will germinate when exposed to soil and moisture. Planting this mix results in an unpredictable patch of vegetation rather than a controlled garden. The outcome is often an undesirable array of fast-growing plants competing aggressively for resources.
The Common Components That Germinate
Most commercial bird seed blends contain grains and oilseeds that retain their full capacity for growth. The most common and vigorous sprouter is the black oil sunflower seed, which has a thin hull and high oil content, making it biologically robust and a primary energy source for birds. Striped sunflower seeds also have a high germination rate, though their thicker shell may slow the process slightly.
Other smaller oilseeds and cereal grains also readily sprout when planted. Safflower seeds are highly viable and produce bushy plants, while various millets, such as white proso millet, quickly germinate to form dense, grass-like patches. Seeds like sorghum (milo) are frequently used as filler and will also sprout, though their viability can vary depending on processing. Grains such as cracked corn or oats, which are often broken, are less likely to germinate successfully than whole seeds.
The Resulting Growth Environment
When bird seed is planted densely, the resulting growth is characterized by intense competition and a chaotic, uneven appearance. Unlike intentional gardening, where seeds are spaced to ensure adequate light and nutrients, broadcast bird seed leads to overcrowded seedlings. The diverse mix of species, all germinating at once, immediately sets the stage for a dramatic struggle for survival.
The large-seeded species, particularly the sunflowers, quickly establish dominance by growing tall and developing wide leaves. This rapid growth allows them to monopolize sunlight, shading out smaller, slower-growing plants like millets and safflower seedlings. The resulting patch becomes a dense, tangled matrix where the majority of plants are stunted due to the lack of adequate light, water, and soil nutrients.
Beyond the Garden: Ecological and Health Risks
Planting commercial bird seed carries the potential to introduce ecological nuisances and health hazards that extend beyond a messy garden. Feed-grade seed is not subject to the same strict regulatory standards as horticultural seed, meaning it often contains contaminants known as “weed seeds.” Studies have found that a high percentage of commercial mixes, sometimes over 90%, contain seeds from noxious species, such as various forms of Amaranthus, including Palmer amaranth or waterhemp.
These contaminating seeds can be non-native or invasive, posing a risk of introducing new, difficult-to-control weeds to a landscape. Some contaminants are resistant to common herbicides, creating long-term agricultural challenges if they establish a population. Commercial seed can also carry fungal spores and bacterial pathogens, which thrive in a damp, soil-based environment. The risk of introducing pathogens like Salmonella or Aspergillus is present, as they can multiply in the soil, creating a localized health risk for both animals and humans.