Here’s what you would typically expect.
Week 1: The kernels absorb water
Although popcorn kernels look dry and hard, they are living seeds if their embryos are still viable.
During the first several days:
- The kernels absorb moisture from the surrounding soil (called imbibition).
- They swell slightly as water enters the seed.
- Enzymes become active, converting stored starch into sugars that fuel growth.
- If the soil stays between about 60–86°F (16–30°C), germination begins relatively quickly.
If the soil is too cold or too dry, very little happens.
Week 2: Germination begins
Viable kernels usually start germinating within 7–14 days.
At this stage:
- The seed coat splits open.
- The first root (radicle) emerges and grows downward.
- Tiny root hairs develop to absorb water and nutrients.
- A protective shoot (coleoptile) starts growing upward toward the surface.
Underground, the kernels may appear soft, cracked, and connected to small white roots.
Week 3: Green shoots emerge
By the third week, many viable kernels have:
- Produced green shoots several inches tall.
- Developed their first narrow leaves.
- Begun photosynthesis.
- Started producing additional roots.
If several kernels were buried close together, you would likely see a cluster of young corn seedlings around the blackberry bush.
What happens to kernels that don’t grow?
Not every popcorn kernel is capable of germinating.
Some may:
- Rot because fungi or bacteria invade them.
- Be eaten by insects, worms, mice, squirrels, or birds.
- Remain dormant if conditions are unfavorable.
- Fail because heat used during processing or long storage reduced viability.
Effect on the blackberry bush
The popcorn kernels generally do not help or harm an established blackberry bush.
Possible effects include:
Minimal competition
- Young corn seedlings have small root systems at first, so competition for water and nutrients is limited during the first few weeks.
Slight nutrient release
- If kernels rot instead of germinating, soil microorganisms break them down, releasing small amounts of nitrogen, phosphorus, potassium, and organic matter. Because a handful of kernels contains relatively little biomass, the fertilizing effect is very small.
Microbial activity
- Decomposing kernels temporarily increase microbial activity in the soil. During decomposition, microbes may briefly use available nitrogen, but with only a handful of kernels this effect is usually minor.
What you would likely see after digging them up
If you carefully excavated the area after three weeks, you might find:
- Germinated kernels attached to white roots.
- The original yellow kernel becoming soft and shriveled as its stored food is consumed.
- Fine branching roots spreading into the soil.
- Green shoots extending above ground.
- Some kernels partially decomposed with fungal growth if they failed to germinate.
Long-term outcome
If left to grow:
- The corn seedlings could eventually reach 5–10 feet (1.5–3 meters) depending on the variety and growing conditions.
- They would compete more strongly with the blackberry bush later in the season for sunlight, water, and nutrients.
- Unless they are removed, mature corn plants may slightly reduce the blackberry’s growth if planted very close.
Most likely overall result
After three weeks in moist spring soil, a handful of viable popcorn kernels would typically result in:
- Several kernels germinating into young corn seedlings.
- A few kernels remaining ungerminated or decomposing.
- Little to no noticeable effect on the blackberry bush during that short period.
The outcome is mainly a demonstration that popcorn kernels are simply a type of corn seed and can grow into corn plants if they remain viable and the growing conditions are favorable.