When to Plant Cucumbers – Measure the Soil Temperature

Cucumber plants should be planted outside at the earliest when soil temperature have reached 60 degrees or higher and air temperatures remain above 55 degrees Fahrenheit.

Using a soil thermometer to measure the soil temperature is the best way to know when to plant specific plants in the garden. A cheap soil thermometer is basically a meat thermometer that reads down to a lower temperature.

You want to measure the soil at a time where you can get a good average, between 9-11 AM when the soil has warmed up a little from the night but not fully heated by the afternoon sun is a great time. Measure the soil by putting the stem of the thermometer into the ground and letting it sit there for a few minutes. Cucumber seeds planted outside will not germinate if soil temperatures are below 60 degrees Fahrenheit.

How to Plant Cucumber Seeds & Transplants

In this video Michael talks about the different ways to plant cucumbers. You can see the mounded row and mounds near the fence that we can use as a trellis. SORRY for the belly shots, trying to keep the sweat out of his eyes!

To plant cucumber seeds make a raised row by mounding up dirt about 8″ high. Make holes along the top of the mound 1″ deep every three inches and put seeds in the holes. If transplanting cucumber plants plant them every 12″ with a 1/2″ of soil on top of the root ball.

I like to plant cucumbers and other vining crops in raised rows. Most vining crops like cucumbers and melons are warm weather plants that prefer sandy loam soil that drains well. Raised rows provide increased soil temperatures and better drainage.

Planting in hills or mounds also gives these benefits but I always find planting in hills or mounds gives a lower plant density than planting in rows. Raised rows get the benefits of both planting styles without the wasted space.

Should You Soak Cucumber Seeds Before Planting?

The point of soaking seeds before planting is to increase germination rates or speed up germination. In my opinion, it is not necessary to do unless you’re using poor quality seeds. Hard seeds like corn or beans benefit the most from soaking before planting.

Temperature is the main consideration for germination rates and speed. Cucumber seeds will not germinate if soil temperatures are not 60 degrees or above. The higher soil temperatures are, the faster seeds will germinate, the colder soil temperatures are, the slower the seeds will germinate.

Cucumber seeds should sprout between 5-20 days depending on temperature. Water the planted seeds while they are in the ground after planting and subsequently when soil dries out until they sprout, and after they sprout!

Best Time to Plant Cucumbers

The best time to plant cucumbers outside is when all chance of frost has passed, soil temperatures have reached 60 degrees, and air temperatures will be remaining above 55 degrees Fahrenheit.

Is It Too Early To Plant Cucumbers?

If average soil temperatures are below 60 degrees or there is still a chance of frost on the horizon it is too early to plant cucumbers. Wait for warmer temperatures or start cucumbers inside.

The Latest Date To Plant Cucumbers

By checking the days to maturity of the variety you’re growing you should know about the latest date you can plant cucumbers. Days to maturity starts when the plant sprouts.

How long your cucumbers will produce for depend on the variety but a good average is 4 weeks so aim to plant 12 weeks before you expect a first frost or temperatures regularly below 50 degrees Fahrenheit. Cucumber plants won’t grow much with temperatures below 50 degrees and a hard frost will take out the plants.

Check out “How Many Cucumbers Do You Get Per Plant” for ideas on increasing cucumber yields.

When to Pick Cucumbers

A large and common problem with gardeners growing cucumber is harvesting the cucumbers too late. You know your harvesting too late if the cucumbers are too big, over 2″ in diameter, or have started to yellow.

This is a major problem because once a cucumber reaches maturity it will signal to the plant that it has produced mature seeds and the plant will stop producing cucumbers and harvested mature cucumbers will be bitter and not good to eat.

To promote continuous fruiting you want to harvest the cucumbers before they have fully matured.

To know the right time to harvest cucumbers you should have a good idea of the right length to harvest at for the variety you are growing. You should check your specific varieties but in general, pickling varieties should be picked at 2-4 inches long and slicing form 5-7 inches long.

Another tip to being ready to harvest at the right time is 7-10 days after seeing an open female flower. Female flowers come out a week or two after male flowers and have what looks like a tiny cucumber just behind the flower.

The flower on the left is a female flower with an ovary behind the flower that once pollinated will grow into a cucumber. Male flowers pictured on the right come out a week or two before female flowers. They have no ovary behind them and will fall off the plant naturally.

Please share below any thoughts you have on knowing when to plant cucumbers.

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