How long it takes a cucumber to produce a harvest-ready crop depends on its variety, but all cuke plants go through these two stages on the way there:
Germination: This is the time it takes the seeds to sprout after they go in the garden. It’s also when you start counting the days before you can expect ripe cukes. Keep notes of the seed packet’s listed number of days until harvest for each cuke variety you plant.
Flowering: On their way to maturity, cukes produce male (pollen-bearing) and female flowers. Identify the females by the thickened stems that are actually baby cukes.
After the first female flowers appear, check the developing fruit every day. Baby cukes grow surprisingly quickly, and some varieties reach the picking stage in as little as eight or 10 days.
The Color Test
Most — but not all– cucumbers are ready to pick when their skin is medium to deep green. Some varieties, however, become yellow, white or other shades when ripe. These include:
‘White Wonder,’ a slicing cuke with pale ivory skin
Lemon cucumbers, named for their round shape and lemon-yellow skin and good for slicing and pickling
Armeneian cucumbers, slicing cukes with pastel-green skin
Sikkim cucumbers, slicing cukes with crackled, rust-red skin weighing up to several pounds each.
Expert gardener’s tip: Saving your seed packets with their pictures of ripe cukes pays off big time when you do the color test.
The Size Test
A cucumber’s type and size also have something to say about when it’s ready to pick. As a general rule, smooth slicing cukes are at their best when they reach 7 to 9 inches long.
For bumpy pickling cukes, the rule is usually 2 inches for gherkins and 3 to 4 inches for dills. For burpless cucumbers, including Armenian and English varieties, measure by diameter instead of length. Pick when they’re 1.5 inches around.
The Taste Test
Cukes left too long on the vine become tough and bitter. Don’t give in to the temptation to let yours grow beyond the recommended picking size. What you sacrifice in size, you’ll be compensated for in numbers. Cucumbers regulate how many fruit they produce at a given time, so picking a cuke as soon as it’s ready encourages the vine to replace it.