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.
Keter Manor Outdoor Apex Double Door Garden Storage Shed (6 x 8ft)
A durable and stylish beige and brown garden storage shed perfect for storing garden tools, equipment, bikes, and outdoor essentials. Weather-resistant, low maintenance, and ideal for any garden or allotment setup.
🌱 Compost & Soil Improvers
Give your garden beds a boost before winter with compost and organic matter.
Shop Compost & Soil Improvers
🌿 Autumn Plant Feed & Fertiliser
Prepare your soil for autumn planting with suitable fertilisers and soil nutrients.
Browse Garden Fertilisers
🥬 Seed Trays & Propagation Kits
Keep growing through autumn by starting suitable hardy crops under cover.
Shop Seed Trays
⭐ Recommended Products — Seed Potatoes & Planting Essentials
• Seed Potato Collection (Early, First & Second Earlies)
A mixed pack of quality seed potatoes to plant for a steady harvest from early summer through to autumn. Ideal if you want variety in size and maturity times.
👉 Click here to see top options
• Certified Seed Potatoes (Single Variety Packs)
Choose popular individual varieties (e.g., Maris Piper, Charlotte, King Edward) to suit your taste and growing goals — consistent results from true seed stock.
👉 Click here to see top options
• Potato Grow Bags / Containers
Reusable, breathable bags designed specifically for growing potatoes — great for patios, small gardens, or increasing yield in limited space.
👉 Click here to see top options
• Potato Fertiliser / Soil Booster
Specially formulated feed to support healthy tuber development and improve yields — apply at planting or as a top-dress during the season.
👉 Click here to see top options
• Potato Planting Guides & Markers
Helpful tools and guides that take you through planting depth, spacing, and care — plus reusable markers to keep track of different varieties.
👉 Click here to see top options
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.