Fill a large bowl with 2 quarts of water and lemon juice.
Prepare artichokes by using a chef’s knife to cut off about ¾ to 1-inch of leaves from the top.
Hold the base of the artichoke and use kitchen shears to trim the ends of the leaves to remove the sharp thorns.
Cut the stem off flush with the base of the artichoke bulb.
Add cut artichokes to the lemon water.
Add 1 cup of water, lemon slices, garlic slices, and rosemary to a 6-quart Instant Pot.
Place the steaming rack on top.
Drain the artichokes by turning them upside down and shaking off the excess water.
Place the artichokes on top of the steaming rack, top side facing up.
Make sure that the release valve is in the "Sealing" position.
Place the lid on the Instant Pot, turn and lock.
Press "Manual" button on the Instant Pot on high pressure, and then set the timer to 20 minutes using the "+" or "-" buttons.
It will take about 10 to 15 minutes for the pot to heat and build up pressure. You will see some steam release from the lid, and then the time will start on the display.
Once the display indicates "On" and begins the countdown at "20", the Instant Pot will beep when the cycle is complete.
Cover the steam release handle with a towel to avoid splattering. Carefully quick-release the pressure from the pot by sliding the steam release handle to the "Venting" position, releasing all of the steam until the float valve drops down.
Open the lid and use tongs to remove the artichokes.
The artichoke is ready when the leaves can be easily emoved and the meat is tender.
Small artichokes (2 inches in size) cook 16 minutes; 4 to 6 will fit.
Medium artichokes (3 inches in size) cook 18 minutes; 3 to 4 will fit.
Large artichokes (4 to 5 inches in size) cook 20 minutes; 2 will fit.
An 8-quart instant pot will need 2 cups of water.
Large artichokes harvested in the early spring and summer may require less cooking time (12 to 15 minutes) compared to late summer/fall artichokes, which need 20 minutes.