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Growth-Plates

4 min readStatus:Seedling

Growth Plates

In child development, growth plates (epiphyseal plates) are cartilaginous zones at the ends of long bones where new tissue is generated. They are the most active regions during growth — and simultaneously the most structurally vulnerable. Growth plate fractures occur preferentially over ligament or bone injuries because the hypertrophic zone lacks both collagen and calcified tissue, making it unable to resist shear stress. The vulnerability is intrinsic to the function: rapid growth temporarily sacrifices structural integrity.

Will Larson applies this metaphor directly to engineering organisations. During periods of rapid company growth, certain teams or functions become growth plates — growing fastest, handling the most critical scaling challenges, and simultaneously most fragile.

Characteristics of Growth-Plate Areas

  • Headcount growing faster than the organisation can effectively onboard
  • Manager-to-engineer ratios exceed the healthy range (above 8–10 engineers per manager) rapidly
  • Normal management cadences (weekly 1:1s, sprint planning, roadmapping) are too slow or too heavy for the pace
  • Documentation, process, and culture cannot keep pace with headcount growth
  • The manager of the area often becomes a bottleneck — decision-making can’t centralise fast enough, but decentralisation hasn’t been established

Why Standard Management Breaks Down

  • New hires overwhelm existing cultural norms before they can absorb them
  • Problems in growth-plate conditions often have unknown solutions — unlike stable environments where playbooks exist
  • Technical debt accumulates faster than it can be addressed
  • The dominant management currency shifts from ideas and strategy to execution at pace

Larson’s Guidance for Growth Plates

  1. Recognise the state explicitly — it is not a normal operational mode; treat it differently
  2. Hire a dedicated leader with explicit authority and resources for the growth-plate area
  3. Accept temporary dysfunction as the cost of growth; don’t enforce stable-environment standards
  4. Set a time horizon — “We accept this chaos for six months, then we stabilise” — and prepare explicitly for the transition out

The Transition Risk

Growth-plate teams build habits that work at high-growth speed: informality, speed over process, improvisation over playbook. When growth slows, those habits become dysfunctional. Teams that stabilise must actively unlearn the growth-plate mode — this transition requires explicit management, not the assumption that stability will self-organise.

The analogy holds: growth plates ossify when bone growth is complete, becoming uniformly strong. The transition must be managed deliberately, not assumed.

Sources

  • Larson, Will (2018). “Managing in the growth plates.” Irrational Exuberance (personal blog). Published March 21, 2018. Available: https://lethain.com/managing-growth-plates/

    • Original formulation of the concept; the blog post adapted into Chapter 2.2 of the book

  • Larson, Will (2019). An Elegant Puzzle: Systems of Engineering Management. Stripe Press. ISBN: 978-1-732-26518-9. Available: https://press.stripe.com/an-elegant-puzzle

    • Chapter 2.2: “Managing in the growth plates” — refined version with adjacent framing on team sizing and management ratios

  • Mirtz, Timothy A., et al. (2011). “The Effects of Physical Activity on the Epiphyseal Growth Plates: A Review of the Literature on Normal Physiology and Clinical Implications.” Journal of Clinical Medicine Research, Vol. 3, No. 2, pp. 51–56. PMC3194019. Available: https://pmc.ncbi.nlm.nih.gov/articles/PMC3194019/

    • Biological foundation for the metaphor: growth plates are structurally weakest precisely because they are growing fastest

  • Hoffman, Reid and Yeh, Chris (2016). “Blitzscaling.” Harvard Business Review, April 2016. Article ID: R1604B. Available: https://hbr.org/2016/04/blitzscaling

    • Parallel framework: hypergrowth requires prioritising speed over efficiency; accepting operational debt is a deliberate decision, not a failure

  • Dunbar, Robin I.M., et al. (2021). “‘Dunbar’s number’ deconstructed.” Biology Letters, Vol. 17, No. 5. Royal Society Publishing. DOI: 10.1098/rsbl.2021.0158. Available: https://royalsocietypublishing.org/doi/10.1098/rsbl.2021.0158

    • At ~150 people, informal social cognition breaks down — a documented inflection point coinciding with key growth-plate transitions where process must formalise

Note

This content was drafted with assistance from AI tools for research, organization, and initial content generation. All final content has been reviewed, fact-checked, and edited by the author to ensure accuracy and alignment with the author’s intentions and perspective.

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