Living up here at 5600 feet like I do I always feel I'm getting a late start on my garden. I am also partial to lemon cucumbers, which can be hard to find even as seeds, never mind as started plants. I've found that presprouting these tender-rooted plants gives them (and me) a fast start. I've read this works just as well for squash, pumpkins, and melons, none of which like being transplanted. And it's very, very easy.
Cucumber seeds germinate best at 90 degrees F, but are perfectly happy growing at 65 degrees F. All you need to do is give them these conditions and they'll get going a week or two faster than if you planted them in either a pot indoors or directly in your garden. Your germination rate will also be much better. I rarely find a seed dated for the current year that fails to sprout, and usually two or even three year old seeds will do fine.
All you need are:
-a paper towel
-a plastic bag
-a warm place
-a twist tie or string, or other way to hang the bag if required
Step 1: Beginning the Process
Soak a paper towel in water.
Fold it in half.
Place your seeds an inch or more apart on the paper towel. It's important to give their roots room to grow without tangling.
Carefully roll the paper towel up.
Place in the plastic bag and seal.
Step 2: Where to Put It?
Now you need a consistently warm spot to keep the plastic-encased seed bag. On top of an insulated water heater may work for you. Near a pilot light or an incandescent bulb (which will need to remain on) are other possibilities. A good rule of thumb is if it feels warm, not hot, to your hand--on a consistent basis!--it should do the trick. If you aren't sure, use a room thermometer to test it. More than 90 degrees F is too much, not to mention that you might set the whole shooting match on fire.
I hang mine above the back of my propane refrigerator (about 85 degrees F), which works very well.
If you've got a handy surface on which to lay the bag, go for it. Otherwise you may need to hang it as I do.
Step 3: Check It Every Day
Check the progress of your seeds every day. Nancy Bubel, in her book The New Seed-starters Handbook (highly recommended), says that nothing will happen for a few days, but that it's important to give your seeds a daily infusion of oxygen daily anyway. My "warm spot" must be warmer than hers, as my seeds generally sprout within a day or two at the most.
Step 4: And Plant!
Once your seeds have sprouted, you can plant them directly into your garden. You may find that the roots of some sprouts have grown into the paper towel. No worry! Carefully tear off the portion of towel containing the sprouted seed and plant paper and seed together. Make a hole a half-inch to an inch deep in your soil (already well amended with finished compost, of course!), put your sprout in, cover, and water it in well.
I generally see the first green leaves poking up in about a week. [And this year was no different. Two tiny green plants were showing 7 days after I put the seeds in the ground, though the overnight low their first night out was 32 degrees.]