How to Tell When Potatoes Are Growing Underground

Because potatoes develop below the soil surface, it can be hard to know what’s happening underground. However, potato plants give several clear above-ground signs that tubers are forming and growing, allowing you to judge progress without disturbing the soil.

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Early Signs That Potatoes Are Growing

The first clues appear above ground.

• Strong, healthy shoot growth
• Thickening stems at the base
• Rapid leaf development

These signs show the plant has established roots and is preparing to form tubers.

Flowering Indicates Tuber Formation

Flowering is one of the clearest signals.

• Flowers usually appear once tuber growth begins
• Tuber initiation happens around flowering time
• Not all varieties flower, but many do

Flowering suggests potatoes are developing underground.

Steady, Vigorous Leaf Growth

Healthy foliage supports tuber growth.

• Dark green leaves indicate good nutrition
• Even growth shows consistent conditions
• Continued leaf growth means tubers are bulking up

Weak foliage can slow underground development.

Soil Mounding and Stem Coverage

Earthing up helps confirm growth stages.

• Buried stems produce stolons
• Stolons develop into tubers
• More buried stem often means more potatoes

Each earthing-up stage supports further underground growth.

Increased Water Demand

Growing tubers increase water needs.

• Plants wilt faster in dry weather
• Soil dries out more quickly
• Regular watering becomes more important

This increased demand usually coincides with tuber bulking.

Slight Soil Cracking or Lifting

Subtle soil movement can be a clue.

• Raised ridges may swell slightly
• Small cracks can appear in dry conditions
• Soil may feel firmer around the plant base

These changes suggest tubers are expanding beneath the surface.

Plant Height and Canopy Size

Canopy size relates to underground activity.

• Taller plants with broad foliage support more tubers
• A dense canopy often means active tuber growth
• Balanced growth is ideal

Excessively tall plants may focus more on leaves than tubers.

What Not to Do: Digging to Check

Avoid disturbing the soil too early.

• Digging damages stolons and tubers
• Disturbance slows growth
• Increases risk of disease

Rely on plant signals instead.

When Tuber Growth Slows Down

Later in the season, changes occur.

• Foliage growth slows
• Leaves may yellow
• Energy shifts from growth to maturity

This signals tubers are nearing full size.

Final Thoughts

You can tell when potatoes are growing underground by watching for strong foliage growth, flowering, increased water demand, and subtle soil changes. These above-ground signals indicate active tuber formation and bulking without the need to dig. Trust the plant’s growth cues, and you’ll know your potatoes are developing well beneath the soil.