A Basic, Small, Cheap, Hydroponic Salad Raft

A Basic, Small, Salad Raft
by: Nature Steve.

Hydroponics is quite a snazzy improvement on the age old art of horticulture. This project is very compact and offers all the benefits of those picturesque coffin-sized systems, but smaller and much cheaper. Enough room easily for 9 pots of lettuce or any other water-loving botanical.

Materials:
9 Party Cups                          - (Box of 1000 for $133 at OfficeMax.com)
3/4" Thick White Styrofoam - ($7 at Home Depot for 6 2'x4' pieces)
Perlite                                      - ($6 on Amazon or cheaper at Home Depot)
Aquarium Air Pump              - ($8 at walmart or amazon, cheap will do)
Air Hose                                  - ($2, make sure size is correct for air pump, e.g. 1/4")
10" Air Stone                          - ($3, make sure stone fits in container you use)
5 Gal. Storage Container    - ($4, buy opaque! clear will hinder root growth)
Seeds or plants

~Paraffin Wax (to coat razor blade)
~Net Cups (alternative to chopped up party cups, they cost money)
~Water (this may be a concern in urban areas, use purified water for hydroponics)

Tools:
Razor Blade (rub with paraffin wax to make your life easier, cuts styrofoam very clean)
Hole Saw - goes on a drill, makes a huge mess with styrofoam, use the razor blade instead.
Permanent Marker - for drawin circles and stuff.

~Vacuum (styrofoam makes a mess, you can't avoid it)

Shape the Raft:
If you are ever forced to cut styrofoam for school, hire a lawyer and sue. Separation of church and state because this stuff is pure satan.

Put the bucket bucket upside down on the styrofoam and trace an outline, cut your raft "X" smaller because it has to fit inside the bucket to slide up and down. My bucket is also concave, it gets smaller as you go down further, so take that into consideration. If you cut it to fit the very bottom it will have a large gap at the top and cause algae growth and various miserable things. If you size it to the middle of the bucket hopefully life will go on.

Create room for your air hose to fit between the bucket side and raft so everything stays free floating.

Cut Some Holes:
Trace the bottom side of a partay cup for a template. Space these evenly across the float, do not force them tight together, you need room for growth and strength in the raft. This container easily holds 9 plants.

When cutting the holes, the cups need to slide far enough down to expose the roots to the water. Anything above the waterline will receive significantly less moisture and probably die. There is the consideration of evaporation keeping the roots hydrated but that is largely dependent on the atmosphere you create.

~If you break the styrofoam in half, fix it. Giving up is not an option.

In a perfect world, you will not use perlite. They have expanded clay balls which are just better in every aspect, order them on amazon. Using these would allow you to just drill large holes in a bunch of cups, much better air and water flow, roots grow easier, no sharp edges. But this is America, so let's do things the hard way for little to no payoff.

Perlite is very small, so the holes we cut have to be very tiny but still room enough for roots to grow out. If the holes are large, the perlite just falls through and you'll have a huge mess to drain from your bucket.

Cut the cups in half.
Using a razor blade, cut long slits in the bottom and sides of the cup.

There is absolutely no methodology applied here, make it so water can get in and there's room to have a tiny root grow out somewhere.

I also cut one side of the cup to allow it to squeeze into the raft with little force on the brittle foam itself.

With all the extra cup tops you have sitting around, make art. Or buy some plastic netting and make more grow cups or something.

Starting seeds in perlite is completely possible. I used self watering planters made from water bottles to germinate all the lettuce I used in this writeup. The perlite must remain very humid for seeds to start, so cover your planters with plastic wrap until leaves appear.

I simply transplanted my germinated lettuce into the raft cups. Having started the lettuce in perlite, removal of the root system was not difficult. All the lettuce came out very easily and required no cleaning, as opposed to starting the plants in dirt.

When transplanting:
Fill the grow cup with perlite
Wet the perlite to remove dust and create a more solid and settled substrate
Create a hole to the bottom with a shovel
Guide root system as deep as possible, if roots are very long, try to guide some through a hole

~If plant is very large, such as a store bought tomato bush, put plant and roots in the cup first before the perlite. Guide many of the roots through the cup to guarantee they reach water. Fill Cup with perlite around the plant.

Fill your bucket with the most expensive purified water you can buy.
Wash your airstone (remove contaminants).
Test with air pump.
Assemble Everything.

Adding nutrients is completely up to the user. There are numerous types on the market, some people suggest using plain powdered miracle grow. Read the label of whatever you buy, adjust according to how much water you are using. A couple teaspoons should be completely adequate for whatever you use, but do not add too much or you'll burn everything.

After freshly transplanting specimens, it is common to not add nutrient for up to 2 weeks. This stimulates root growth as the plant seeks nutrient rich "soil." Having an established root system is incredibly crucial for this project to work correctly. Research your intended plants and try to accommodate.

Precautionary Notes:
Air pump must be located higher than the waterline, in the event of a power outage the water could backup into the pump and cause an explosion.

Any power wires around water can kill you. Don't let your kids yank on the air hose, don't let your cat attack the raft because you think it's cute and you want to show your friends on youtube because you will be electrocuted to death.

Place a drip loop on all pump and light power wires to negate water dripping into your outlets, you could be electrocuted and died or your house will burn down and crush you in a fiery flame, the firefighters will say it was the most gruesome death in history and they couldn't save you even though your screams reverberated for miles. Though your cat and children were not home they are now orphans and homeless with no family friends to take care of them because you spent your nights making lettuce rafts instead of socializing with other humans.

This is a very basic system with great outlook. If the party cups work that is fantastic. Perlite may or may not be a viable substrate for this type of system because of the low amount of air and water flow to the root system. Watering is not such an issue, there's 5 gallons of it, but make sure it doesn't run low or the raft could jam possibly.

I am interested to see if seed germination is possible directly in the raft with a cup. A full cycle sow - harvest with never removing from the raft would be quite impressive.

If anyone makes this or has suggestions, please add your insights.