A full incubator tray of brown, cream, and blue-green chicken eggs, each marked '6-4' for the set date.

🥚 HatcheryPosted June 18, 2026

Mixed-flock hatch — Day 14 in the incubator

Set on June 4. A full tray of brown, cream, and blue-green eggs, all from our own hens.

Read this to your kid first

"We set a full tray of eggs on June 4 — brown, cream, and blue-green, all from our own hens. Today is Day 14 of 21. The chicks are fully formed in miniature. We're going to learn why the shell colors are different, and then we'll each make a guess about how many will hatch and what color shells will be most common."

Field notes

On June 4 we filled the incubator with eggs from our own flock — brown ones from the Marans and Australorps, cream from the Brahmas, and the blue-green ones from the Olive Eggers and Easter Eggers. Every egg is marked '6-4' in pencil so we know the set date.

Today is Day 14. The thermostat reads 99.5°F. The auto-turner tips the eggs every hour so the yolk doesn't stick to one side of the shell. The chicks are fully formed in miniature now — they spend the next week mostly growing and absorbing the yolk.

We are guessing how many of each shell color will hatch, and what the chicks will look like. Egg color is set by the hen; chick color comes from both parents.

The learning

What's actually happening

The egg is a complete life-support system

The yellow yolk is the chick's food. The clear 'white' (albumen) is water and protein cushion. The shell is mostly calcium carbonate — the same stuff as chalk — and has about 7,000 microscopic pores that let oxygen in and carbon dioxide out.

What's happening this week (Days 14–18)

By Day 14 the chick is fully formed in miniature. Toes are separated, feathers are coming in, and the egg tooth — a hard bump on the beak the chick will use to break out — is in place. Most of what happens this week is just growing and absorbing the rest of the yolk.

Why we mark the date

Day 18 is 'lockdown' — we stop turning the eggs and raise the humidity so the chicks can hatch without getting stuck. If you mix eggs from different set dates and don't mark them, you can lockdown too early or too late and lose the whole batch.

Why shell colors are different

All eggs start out white inside the hen. Brown breeds paint a layer of pigment (protoporphyrin) on the outside of the shell. Blue-egg breeds dye the shell all the way through with biliverdin — the same blue-green pigment that makes a bruise look greenish.

Words to know

Candling: Shining a bright light through an egg to see the chick growing inside.
Embryo: A baby animal in its earliest stage of growth.
Air cell: A small pocket of air at the fat end of the egg. It grows bigger as the chick gets bigger.
Lockdown: The last 3 days of incubation. We stop turning the eggs and raise the humidity so the chick can hatch.

Your turn

Make your guesses

Enroll a kid to save guesses.

Guess

Count the eggs you can see in the photo. How many of those do you think will hatch into healthy chicks?

Hint: A good hatch rate for home-laid eggs is around 75–80%.

Pick one

Which shell color will be MOST common in the hatch?

Wonder

Why do you think the incubator has to TURN the eggs every hour for the first 18 days?

Hint: Think about what would happen if you sat in the same position for three weeks straight.

Try this at home

▸Hold a flashlight against a brown egg from the fridge in a dark room. You won't see a chick (those are unfertilized), but you WILL see the yolk shadow and the air cell.
▸Find chalk in your house. Tap it with your fingernail — that's the same calcium carbonate an eggshell is made of.
▸Mark today's date and count forward 21 days from June 4. That's hatch day.

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