Best Way to Fertilize Young Cucumber Plants to Get Them Growing Strong Early 1

Every spring, we get the same burning question: how do you get young cucumber plants off to a strong start and keep them producing all summer long? Well, I’m here to spill the beans—or rather, the cukes!

Cucumbers grow fast, like really fast. But how do these lean climbers give you so many massive fruits? The secret is in their diet: they drink and eat a lot—an awful lot! If you don’t keep their “bellies” full, they might just let you down. And the key to success is starting early. Giving your cucumbers the nutrients they need when they need them is crucial. But remember, both how and when you fertilize can make a huge difference in the longevity of the plant and how many cucumbers you’ll harvest.

If you fertilize and water your cucumbers correctly, they will start fruiting along with your tomatoes, even though you plant them roughly a month later. And within three weeks of moving the seedlings into your veggie garden, you can see the first flowers. Incredible, right?

Wonder how you can feed your cucumbers well, how to make them happy so you can start harvesting them early, and get new fruits for a long time, plump and juicy for your dinner table? Here is what to do!

Feeding Cucumbers – From Babies to Adults and Beyond

Feeding Cucumbers – From Babies to Adults and Beyond

Fertilizing cucumbers requires you to be regular, and to give them the right “food”. You need to start very early with the seedlings, because they start growing soon and fast, and, as we said, they can start flowering as early as three weeks after transplanting (though those are male blossoms that appear first).

So, it is a long process, and it starts with the seedlings.

Pre-Fertilize the Soil for Cucumber Seedlings

How to Pre-Fertilize the Soil for Cucumber Seedlings

The best way to pre-fertilize the soil of your cucumber seedlings’ beds is with compost! But you need to be very generous with it! In fact, these veggie bearing climbers can literally grow in soil that’s made up almost completely by it!

Give them at least 2 inches of compost (5.0 cm), and there’s an old trick some gardeners use; make a little mound of compost all around your cucumber seedling, up to 4 inches tall (10 cm), just after you have transplanted them. But if you can’t…

The First Fertilizer for Cucumber Seedlings – Like Milk for Babies

The First Fertilizer for Cucumber Seedlings – Like Milk for Babies

If you are using a slow release organic fertilizer instead of compost, your cucumbers’ first “food” must be different from the ones you will use later on. In fact, you don’t want these juicy fruit bearing vines to grow too many leaves once they start flowering, but at this stage, they are like babies, and they need to grow fast and strong.

So, choose a balanced fertilizer with fairly high NPK, like 12-12-12 at this stage.

But will any fertilizer do?

Can You Use Manure to Pre-Fertilize Cucumber Seedlings?

Can You Use Manure to Pre-Fertilize Cucumber Seedlings?

Of course you can, as long as it is well rotted (at least 2 years old), or you will burn them, but it’s not the best choice. Cow manure especially is far too rich in nitrogen, and you risk getting lots of leaves, but very few cucumbers indeed…

When Should You Fertilize Your Young Cucumbers Next?

I said that cucumbers are hungry eaters, and you should start fertilizing them about 2 to 3 weeks after you have transplanted them. By then, they are already adults, and you need to change from “baby food” to a new diet.

Post Transplant Fertilization Routine: What and How Often to Feed Cucumbers?

The First Fertilizer for Cucumber Seedlings

From now on, you will need to give your young cucumbers a light and fast release fertilizer which is low in nitrogen. Remember, you want fruits and not leaves! 

If you are using an off-the shelf fertilizer, the ideal NPK is 2-3-6. If you can’t find it, 2-5-8 will do.

The idea is to feed them little, but feed them often!

So, I suggest you feed your young cucumbers every 2 to 3 weeks maximum, especially when they are young, but all through their fruiting season.

Cucumbers Like Their Food Warm!

Cucumbers Like Their Food Warm!

As you know, you cannot transplant cucumber seedlings till the soil is steadily above 60°F (15°C), and that’s why we do it later than tomatoes and even peppers. And this will give you a clue, these babies like to keep their “feet” (roots) warm!

So, here’s a trick of the trade for you; when you feed cucumbers, mix the fertilizer into lukewarm water, and give it to them at night! This is especially helpful early in the season, when the plants are still young.

But how about if you want to use your own, home-made fast-release liquid fertilizers? Which options do you have to plump up your cucumbers?

Fertilize Young and Old Cucumbers with Chicken Manure Water

Fertilize Young and Old Cucumbers with Chicken Manure Water

If you have chickens, don’t waste what comes out from their “backside”… Not just the eggs though… You will eat those, while your cucumbers will benefit from their poop…

The process is very simple…  Keep a bucket where you store the chicken manure (you have to put it somewhere, anyway), but only fill it to about two thirds. Then, cover it with water, and leave it there…

It will turn into fast release chicken manure based fertilizer; unlike cow manure, it has a fairly low nitrogen content, while it’s fairly high in phosphate, with an average NPK of 5-4-2. It’s a “light meal” as well…

Every fortnight, scoop off the top of the liquid fertilizer, and dilute it to 1:10 into the water you give to your cucumbers… Then, top up the bucket and you will have plenty for the next time you need it.

Horse manure will be good as well for cucumbers.

Alternatives to Chicken Manure Liquid Fertilizer for Young Cucumbers

Alternatives to Chicken Manure Liquid Fertilizer for Young Cucumbers

But how about if you don’t have chickens (or a horse)? In this case, you can use any green macerate, like nettle, comfrey, or even a mix from cut grass and other leaves (those you discard from your lettuce, uprooted veggies etc…).

The process here is simple too, again, using a bucket, filling it to two thirds with the leaves, then covering it with water. Wait for a week or two, and it’s ready.

If you want to speed up the process, add some molasses, and remember that it will increase in strength over time, before all the nutrients dissolve completely.

But now, do you want to boost this fertilizer, or other home-made ones?

How to Raise the Phosphorus Content of Your Home-Made Liquid Fertilizer for Young Cucumbers

If you want to boost your cucumber crop, you will need a bit more phosphorus in your fast-release home-made fertilizer… And there are simple ways to do it, still using the same bucket… Simply add, for each gallon (4 liters):

  • A spoon (or handful) of rock phosphate, or..
  • A cup of bone meal.

You can also do it as you water and fertilize your cucumbers, but mix them well..

Feed Your Cucumbers Well, and They Will Feed You

So, it’s not hard to get a massive cucumber crop if you know how to fertilize them… Remember to give them little but frequently, and they will fruit insanely, and, of course, water them generously.  And you will have lots of cukes to eat fresh or pickled!

Amber Noyes

Written By

Amber Noyes

Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.

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