Intro to DIY Hydroponics for Growing Lettuce (and Other Veggies) Indoors on a Budget

Raised in California, in a time of great abundance and fresh produce everywhere, I had salads most every evening with dinner.  Sometimes we had a frozen vegetable.  Canned goods sat on the shelves and then got tossed when they reached their best-by date.  My husband was raised in just the opposite manner—canned veggies were on the table every night and fresh salads were a rarity. 

As the one charged with making dinner every day, I did it my way—salads were the go-to side.  I really can’t live without them.  However, my husband was always making the argument for canned veggies—we needed them in our food storage and they naturally needed to be rotated to prevent waste.  And they were often less expensive.  I learned to compromise a little on the issue.  But I usually set a bad example for the kids and only served myself a tiny portion or didn’t eat even eat the canned veggies at all.  Bad Mom!

Unfortunately for my husband, the children mostly sided with Mom—they preferred salads while making an exception for canned corn.  Canned green beans and peas were eventually simply refused.  The problem is, naturally, that we can’t store fresh lettuce.  And we can’t grow it in the garden in winter.  And like many others, I still don’t have a greenhouse or walipini for growing our winter vegetables. 

Of course, I had heard about hydroponic growing, but it all seemed so complicated and expensive.  Until I came across the Kratky hydroponic method.  It seemed very do-able and very inexpensive.  And so far, it is working really well.  I haven’t yet harvested any lettuce, but the plants are about 1.5” tall now with a few leaves each.  And it has been really easy. 

Here’s what you need to get started:

Light source.  I already had the LED grow lights that I use for starting seeds in the spring.  If you live in a warmer climate you can just set plants outdoors.  A sunny window probably will not provide enough light for growth.

Containers.  The most common container for growing lettuce hydroponically using the Kratky method is a gallon milk jug.  Other potential containers include milk cartons, canning jars, #10 cans (though they will rust out pretty quickly), Ziploc bags, and plastic salad containers. 

Net pots.  You can get these on Amazon (search “plastic mesh net pots”).  I bought a package of 100 2” pots.  In retrospect, I wish I hadn’t gotten so many.  I’m not a commercial operation and these pots are reusable.  I also think there was an option to get an assortment of sizes, which I wish I had done.  I don’t see that option now.  I think the 2” size is perfect for growing lettuce, but I also want to try growing tomatoes and peppers, and a larger size would be nice.  Net pots can be improvised by cutting up plastic dairy containers with an exacto knife.  If you are using Ziploc bags as your container, the net pots are not necessary.

Rockwool cubes.  These are apparently not essential, but they are convenient.  Rockwool, also known as stone wool or mineral wool, looks like fiberglass or cotton candy.  Basically, rocks are heated and turned into a liquid, which is then spun into fine fibers like fiberglass.  Then the rockwool fibers are compressed together.  They are used in insulation and growing plants.  (I have also read of pillow stuffing being used and gave it a try myself.  It didn’t work for me.)  Rockwool fiber cubes are also available on Amazon in a variety of sizes.  I got the 1.5” cubes.  They can be reused up to six times. 

Nutrients.  This was probably the most confusing aspect to research.  Vegetables grown hydroponically have different nutrient demands than those grown in the soil.  Of course, that is because plants get a lot of nutrients from the soil.  So you really have to provide a different nutrient supplement for optimal growth.  And it’s not likely to be on the shelf at Home Depot.  Again, Amazon to the rescue, but there are other sources.  Unfortunately, there doesn’t yet seem to be one simple product to add.  You’ll need MasterBlend (4-18-38), Calcinit (calcium nitrate, 15.5-0-0), and Epsom salts.  (I see now that Amazon has a combination kit offer with all three.  I’m pretty sure that wasn’t an option when I was looking a few months ago.)

pH meter or test strips.  As noted in previous articles, maintaining the optimal pH for the vegetable you are growing is essential for maximum production and flavor. 

pH Up and Down kit.  This contains solutions to raise or lower the pH of your nutrient solution as needed.  You may not need it to get good growth from your plants.  However, if your water is very hard or very soft, you’ll probably want to have it on hand.  I’ve got very alkaline water here and need to use quite a bit of the pH down solution. 

Seeds.  Whatever you wish to grow.  Use strong, fresh seed for best results.

The above are the basics for growing lettuce using the Kratky system of hydroponics.  If you decide to get into growing tomatoes, peppers, or cucumbers, the only additional items you’ll need are 5-gallon buckets and a trellis for the plants to grow on. 

Links to related posts:

pH Strips or Meter?

The Medicinal Uses of Epsom Salts

Best-By Dates:  What Those Numbers Really Mean