Did you know that button mushrooms, cremini mushrooms, and portobello mushrooms are all the exact same species – just harvested at different ages? If you’ve ever wondered what a button mushroom becomes when it matures, you’re about to discover the fascinating transformation of Agaricus bisporus through its lifecycle.
Agaricus bisporus at a glance
- Species: Agaricus bisporus (the same for all three types!)
- Common varieties: Button mushroom, cremini (baby bella), portobello mushroom
- Key difference: Maturity stage only – it’s literally just age
- Growing time: 14-28 days from pin to portobello
Whether you’re comparing button mushrooms vs baby bella or wondering if portobello and button mushrooms are the same species – yes, they absolutely are! Let’s trace this incredible journey step-by-step.
The Agaricus bisporus mushroom lifecycle: from spore to fruiting body
1. Spore germination (Days 1-10)
All Agaricus bisporus mushrooms – whether destined to become button, cremini, or portobello – begin as microscopic spores. When these spores land on suitable substrate under the right conditions:
- Temperature needed: 70-75°F (21-24°C)
- Humidity required: 85-95%
- Time to germinate: 5-10 days
- What forms: Thread-like filaments called hyphae
2. Mycelial growth (Days 10-25)
The portobello mushroom mycelium (same as button mushroom mycelium) expands rapidly:
- Forms a white, cotton-like network throughout the substrate
- Breaks down organic matter for nutrients
- Establishes the foundation for fruiting bodies
- Critical fact: This mycelium is identical whether growing button or portobello mushrooms
3. Primordia formation (Days 25-30)
Pin-like structures emerge from the mycelium:
- Size: 2-5mm initially
- Color: White to light brown
- Key point: These pins will become button, cremini, or portobello depending on when harvested
4. Fruiting body formation (Days 30+)
This is where the magic happens – the rapid transformation begins!
Distinct maturity stages of Agaricus bisporus
Stage 1: Button mushrooms (button stage of mushroom)
Timeline: 14-17 days from pinning
Cap size: 20-30mm (about 1 inch) Velum mushroom characteristic: Completely intact, covering all gills Color: Pure white to cream Texture: Soft, high moisture content (92-94%) Flavor: Very mild, almost neutral
Button mushroom gills: Completely hidden by the velum (veil). If you cut a button mushroom in half, you’ll see pink gills tightly enclosed.
Growing tip: Button mushrooms double in size every 24 hours at this stage!
Stage 2: Cremini mushrooms (baby bella mushrooms)
Timeline: 17-21 days from pinning Cap size: 30-40mm (1.5-2 inches) Velum: Starting to tear, partially revealing gills Color: Light to medium brown Texture: Firmer than buttons, moisture content drops to 90-92% Flavor: Noticeably earthier and richer
Are cremini mushrooms same as baby bella? Yes! These are just marketing names for the same developmental stage.
Key identifier: The veil is breaking but not completely gone – you can see some gills peeking through.
Stage 3: Cup stage (button cup mushroom)
Timeline: 19-23 days from pinning Cap size: 30-50mm (2-3 inches) Velum: Mostly torn away Cap shape: Cup-like, beginning to flatten Gills: Clearly visible, turning from pink to light brown
This intermediate stage is rarely sold commercially but represents the transition from cremini to portobello.
Stage 4: Mature button mushroom becomes portobello
Timeline: 21-28 days from pinning Cap size: 40-150mm (4-6 inches typically) Cap shape: Completely flat or slightly curved upward Gills: Fully exposed, dark brown to black Texture: Dense, meaty, moisture content 88-90% Flavor: Rich, intense, umami-packed
Important: A mature button mushroom IS a portobello mushroom – they’re the same organism!
Fun Fact: Button mushrooms almost double in size every 24 hours during this early stage. They are popular for their subtle taste and can easily absorb spices and sauces.
Chemical and nutritional changes through maturity
1. Dry matter and water content progression
| Stage | Water Content | Dry Matter | Result |
|---|---|---|---|
| Button | 92-94% | 6-8% | Soft, delicate |
| Cremini | 90-92% | 8-10% | Firmer bite |
| Portobello | 88-90% | 10-12% | Dense, meaty |
2. Protein and carbohydrate shifts
Protein changes:
- Button: 2.5g per 100g fresh weight
- Cremini: 2.7g per 100g
- Portobello: 3.1g per 100g
The protein concentration increases as water content decreases.
3. Chitin and texture development
What makes portobellos meaty?
- Chitin content increases 40% from button to portobello stage
- Cell walls thicken and strengthen
- Fiber content rises from 0.9g to 1.3g per 100g
4. Flavor compound intensification
Umami development:
- Glutamate levels increase 300% from button to portobello
- 5′-nucleotides double in concentration
- Volatile aroma compounds multiply by factor of 5
How to cook button mushrooms at each stage
Button mushrooms: mild versatility
Raw applications:
- Thinly slice for salads (2-3mm thick)
- Whole in crudité platters
- Quick pickle in vinegar for 30 minutes
Cooked methods:
- Sauté 5-7 minutes until golden
- Add to soups in final 10 minutes
- Stuff whole buttons with cheese mixture
Pro tip: Don’t wash button mushrooms – wipe with damp paper towel to preserve texture.
Cremini mushrooms (baby bella): balanced flavor
Best uses:
- Pasta sauces (slice 5mm thick)
- Risotto (quarter or halve)
- Pizza toppings (slice thin)
Cooking technique: Sauté on high heat to evaporate moisture first (3-4 minutes), then reduce heat and add seasonings.
Portobello mushrooms: meaty and robust
Grilling perfection:
- Remove stems and scrape out dark gills if desired
- Marinate 15-30 minutes (balsamic, soy sauce, garlic)
- Grill 4-5 minutes per side at 400°F
- Internal temp should reach 160°F
Roasting method:
- 425°F for 20-25 minutes
- Brush with oil, season generously
- Flip halfway through
Nutritional comparison: button vs cremini vs portobello
| Nutrient (per 100g) | Button | Cremini | Portobello |
|---|---|---|---|
| Calories | 22 | 22 | 26 |
| Protein | 2.5g | 2.7g | 3.1g |
| Fiber | 0.9g | 1.1g | 1.3g |
| Potassium | 318mg | 356mg | 437mg |
| Selenium | 8.9μg | 11.2μg | 15.4μg |
| Vitamin D | 0.2μg | 0.3μg | 0.4μg |
Growing portobello mushrooms (and button/cremini)
Since they’re all the same species, growing methods are identical – only harvest timing differs!
Substrate options for growing baby bella mushrooms
Best cremini mushroom substrate:
- Composted manure mix: 40% horse manure, 40% straw, 20% supplements
- Commercial blend: Pre-made mushroom compost
- DIY mix: Straw, gypsum, wheat bran
Growing timeline for portobello mushrooms
Complete growing portobello mushroom schedule:
- Days 1-14: Substrate preparation and pasteurization
- Days 15-25: Spawn inoculation and colonization
- Days 26-30: Casing layer application
- Days 31-35: Pinning initiation
- Days 36-42: Button stage (harvest here for buttons)
- Days 43-47: Cremini stage (harvest for baby bellas)
- Days 48-56: Portobello stage (harvest for full size)
Frequently asked questions
Are portobello and button mushrooms the same? Yes! They’re the exact same species (Agaricus bisporus) at different maturity stages. Button mushrooms are harvested at 2-3 weeks, portobellos at 4-5 weeks.
What’s the difference between baby bella vs button mushrooms? Baby bella (cremini) mushrooms are 3-7 days older than button mushrooms. They’re browner, slightly larger, and have a deeper flavor.
Can you see button mushroom gills? No, button mushroom gills are completely covered by the velum (veil). Once this veil breaks, it becomes a cremini.
How long does it take to grow portobello mushrooms? From spore to portobello takes 45-60 days total. From pinning to portobello-ready is about 21-28 days.
Are button cremini portobello all the same mushroom? Absolutely yes – all three are Agaricus bisporus at different ages: button (youngest), cremini (middle), portobello (mature).
What does mature button mushroom look like? A mature button mushroom IS a portobello – flat cap, exposed dark gills, 4-6 inches diameter.
Ready to explore mushroom development?
Now that you understand how button mushrooms transform into portobellos, you can make more informed choices at the grocery store or even try growing your own. Remember – whether you prefer delicate buttons, earthy creminis, or meaty portobellos, you’re enjoying the same amazing species at different points in its fascinating lifecycle.
Want to see this transformation yourself? Consider starting a mushroom growing kit and harvest at different stages to taste the evolution of flavor firsthand!
