Incubating Speckled Sussex Eggs: Temperature, Humidity, and Lockdown

Our general guide to hatching eggs at home covers the basics of choosing an incubator. This article goes deeper on the calendar: what you do before day one, what changes at day 10, and why the last three days deserve more attention than the first eighteen. The settings below come from university extension guidance, but your incubator's manual has the final word, because models differ in where they measure temperature and how they handle humidity.

Speckled Sussex lay brown eggs, and the breed is a heavy dual-purpose type, so nothing about the eggs requires special treatment. What matters is the quality of the eggs you set and how steady you keep the machine. If you are still looking for fertile eggs, agriculture.directory can help you find breeders near you.

Before Day One: Choosing and Storing Eggs

The University of Maryland Extension fact sheet Hatching Eggs at Home gives plain advice on this stage:

Pick clean, normally shaped eggs of average size, from a flock that includes a rooster.
Collect eggs daily.
Store them big end up in a cool spot, about 65 to 70 degrees Fahrenheit, away from direct sun.
Do not wash them, and set them within seven days. The sheet says eggs stored up to seven days lose little fertility.
If the eggs came by mail, let them rest for 24 hours before setting.

Grocery store eggs are not fertile and will not hatch. If you are choosing which hens and cocks supply your eggs, our guide to roosters and fertility covers the pen setup.

Temperature and Humidity

The same fact sheet lists an incubation temperature of 99.5 degrees Fahrenheit for chickens and humidity of 55 to 60 percent during incubation. Other guides give slightly different numbers, and forced-air and still-air machines are often treated differently, so follow the manual that came with your incubator. Two habits matter more than the exact figure:

Run the incubator for a day or two with no eggs in it, until the numbers settle.
Check a separate thermometer and hygrometer. The built-in display on a cheap unit can be off.

Place the thermometer where the manufacturer advises, and avoid opening the lid more than necessary. Every opening drops the temperature and humidity.

Turning and Candling

Eggs need turning because embryos can stick to the shell membrane if they sit in one position. The University of Maryland sheet calls for turning at least five to six times a day, which is why automatic turners are popular. If you turn by hand, mark one side of each egg with a pencil so you can see at a glance that every egg has been flipped. Wash and dry your hands first, because oils and bacteria on the shell are not welcome.

Candling means shining a bright light through the egg in a dark room. The sheet suggests starting after day 10. Eggs with a growing embryo look dark, and infertile eggs look clear. Remove clear eggs and eggs with dead embryos, because they can rot and spoil the neighbors. One caution from the poultry industry: a clear egg is not always infertile. As ThePoultrySite explains, early dead embryos can be mistaken for infertile eggs when candling alone is used, so cracking open a few clears helps you work out what went wrong.

Lockdown: Days 18 to 21

Lockdown is the name for the last stage. According to the Maryland sheet, you stop turning on day 18, three days before the expected hatch, so the chicks can orient themselves for hatching. Chicken eggs hatch at 21 days. Here is what to do:

Stop turning and remove the automatic turner or lay the eggs flat, following your incubator's directions.
Raise the humidity. The Maryland sheet says to bring it to about 70 percent when the first pip hole appears, and many incubator makers advise raising it at the start of lockdown. Follow your manual.
Keep the incubator closed. Opening it during hatching lets humidity escape and can cause shrink-wrapped chicks, where the membrane dries and sticks.
Be patient. Hatching is spread over many hours, and some chicks pip and then rest for a long time.

The urge to help is strong, and it is usually a mistake. Pulling pieces of shell away from a chick that is not ready can cause bleeding. If a hatch stalls, resist the urge to intervene during the first hours and ask an experienced poultry keeper or your local extension office for advice.

After the Hatch

Let chicks dry in the incubator until they are fluffy and active, and then move them into a prepared brooder. Our guide to brooder setup has the details. Keep a log of what you set, what you candled out and how many chicks hatched. That log is the best tool for improving your next hatch, and it is discussed further in our article on hatchability benchmarks.

Common Causes of a Poor Hatch

Temperature swings. Power cuts, drafts, direct sun or a placement near a window.
Humidity off target. Too low or too high through the whole run.
Old or poorly stored eggs. Eggs held too long or in warm rooms.
Poor fertility. Too few cocks, an overworked cock or hens kept with a rooster for a short time.
Dirty eggs and equipment. Disinfect the incubator between hatches.

The Speckled Sussex is not a difficult breed to hatch, and a careful beginner can do well. For a lighter take on how farm folks view eggs once they are laid, farm.fm ran a tongue-in-cheek piece about egg recognition.