If you have ever attempted to start plants indoors before your last frost, you probably know what it is to get a root bound plant. No matter the size of your growing container, it does not take the roots too long to find its outer boundaries. This method uses the benefits of hydroponic growing to keep those roots thriving, while preparing your plant to live in soil.
Step 1: Watch the Video
This Youtube video leads you through all of the steps of converting red solo cups into an outstanding hydroponic/soil planting solution.
Step 2: Keep a Couple of Your Old Solo Cups
You can use new ones of course, but why not get some use out of them first. We don't judge you based on what was in the cup prior to starting the project.
Step 3: Let's Put Some Holes in the Bottom of One Cup
Or I have found you can easily do up to five of these at a time, but you will want one hole-free cup for every cup into which you put holes. You can use a nail, scissors, box knife, any number of things to cut your cups; however I find that for the smoothest process and the least chance of unintentionally cracking out your cup, warming a screwdriver over an open flame for about a minute and then pushing down with some force and melting through works best.
Step 4: Put Potting Soil Into the Cup That Has the Holes
I have used straight compost for this before as well. Whatever growing medium you would normally use for a potted plant should be used here.
Step 5: Place Inside the Solo Cup Without Holes
Step 6: Plant Your Seedling Into the Cup
It is time to put your seedling into the new creation. Plant it like you normally would when transplanting a seedling into a larger pot. Then give it a good initial watering. There are drainage holes in the inner cups, so your plant should not get water logged, and the outer cup will prevent water from spilling out.
Step 7: After a Good Initial Watering, Water Sparingly
You want those roots to seek out the holes in the bottom. If the soil goes completely dry and there are not yet roots in the bottom, make sure to water to keep your plant alive, but as soon as you see a root peeking out the bottom of the inner cup, quit watering from the top.
Step 8: Add Hydroponic Solution to the Outer Cup
Once you see that root peeking through, add hydroponic solution to the outer cup. The roots will thrive, and the plant will get tons of nutrients from the hydroponic solution. Your plant will grow as if it was in a much bigger pot, and be very health to transplant outside later.