Cucumber plants should be seeded or transplanted outside in the ground no earlier than 2 weeks after the last frost date. Cucumbers are extremely susceptible to frost and cold damage; the soil must be at least 70ºF for germination. Do not plant outside too soon! Our last frost is easily May 15th.
I know you don’t like to hear this but this is also what the Old Farmer’s Almanac says.
Cucumbers By The Editors
An easy-care vegetable that loves sun and water, cucumbers grow quickly as long as they receive consistent watering and warmth. Don’t let cucumbers get too large before you pick or they will taste bitter! See how to grow and harvest cucumbers.
ABOUT CUCUMBERS
There are two types of cucumber plants: vining cucumbers and bush cucumbers.
Vining cucumbers grow on vigorous vines shaded by large leaves. The growth of these plants is fast, and the crop yield is abundant if you care for them properly. Vining varieties grow best when trained up a trellis or fence. They will be cleaner—versus those that grow directly atop soil—often more prolific, and easier to pick.
Bush cucumbers, however, are nicely suited to containers and small gardens.
Make successive plantings (every two weeks for continued harvests). In already-warm soil, cucumbers will grow quickly and ripen in about six weeks!
PLANTING
WHEN TO PLANT CUCUMBERS
Cucumber plants should be seeded or transplanted outside in the ground no earlier than 2 weeks after the last frost date. Cucumbers are extremely susceptible to frost and cold damage; the soil must be at least 70ºF for germination. Do not plant outside too soon!
To get a head start, sow cucumber seeds indoors about 3 weeks before you plan to transplant them in the ground. They like bottom heat of about 70ºF (21ºC). If you don’t have a heat mat, put the seed flat on top of the refrigerator or perch a few on top of the water heater.
Taken from https://www.almanac.com/plant/cucumbers
Till next time this is Becky Litterer, Becky’s Greenhouse Dougherty Iowa beckmall@netins.net 641-794-3337