Basic Pointers on Your New Hydroponic System

Basic Pointers on Your New Hydroponic System
I get a lot of questions about what type of systems to use for various crops, how to size the reservoir, and how much to feed.  I'll briefly cover a few of those topics below.  If you have further questions, please feel free to post in the comments. 
Q: Will a system of tubes work for growing a variety of crops if I space them 1 foot apart with growing sites at 18" on center (OC)?
A system like that should work fine for lettuce and herbs.  The spacing between grow sites might be a bit large, depending on the variety of plant being grown.  I think I have a 12" OC spacing for my lettuce, with holes drilled at 6" OC for basil.  I built my system with 2" schedule 40 PVC and drilled 1 7/8" holes for 2" net pots.  It works well for lettuce, basil, and Joi Choi.  Too small for some of the bigger rooted things like tomatoes, peppers, etc. 
Tomatoes, cucumbers, and peppers, you would probably want to run a drain to waste coir system or look at using something like dutch buckets or 6" PVC because the roots are so big.  Coir is more forgiving with nutrient balance (it's more like soil) but with PVC you could recycle the water and nutrients.  If you're just starting with hydro, I'd go with drippers and coir until you get the feel for it.  You may decide to stay with coir (I have). 

Q: Would you grow cole crops in a hydroponic system?
Cabbage and other cole crops I wouldn't bother growing unless you have a good market for them or they're of special interest to you.  They take a up a lot of space and don't produce a lot of end product in some cases (like broccoli), or aren't worth much (like cabbage).   They also develop more robust root systems than something like basil or lettuce, which means you'd need a bigger tubing system which increases the cost of their production.
Q: How big should my reservoir be, and how do I decide on a PPM concentration for my nutrients?
Lettuce and basil won't drain a reservoir too fast, but the fruiting crops will drain it in no time.   Depending on the size of your system, you'll need to think about using a minimum of a 25 gallon tank, or maybe even a couple IBC (250 gallon) tanks.  Your system will use a lot more water than you may expect, especially as the weather warms and the plants increase in size.   A good rule might be 1/2 gallon of reservoir per leafy green, and 2-4 gallons of reservoir per fruiting plant. 

I always start out with a very low PPM concentration for all crops, and then it increases depending on what I'm growing.  Start at somewhere around 150PPM for a few days, and start to work it up as the plants get bigger.  They all feed at different rates, so this part is sort of an art of monitoring the plants and responding to their indicators to determine dosage as they grow.  Once they're about 80% of the way to final size, you should be at something like 800PPM for lettuce, maybe 1000PPM for basil, and tomatoes and fruiting crops will be up around 1,500-1,700PPM.  Deciding these numbers is really all about experience which will come from trial and error, and depends on your varieties, the weather, fruit load, etc.  It's not hard to figure out as you go, but there's no absolute set of numbers.  However, you're better on the low side rather than the high side because you can correct up quickly and easily.  Too high and you can harm or kill the plants, and that's hard to come back from. 

You'll also mix your nutrients based on what crop you've got in the system.  I start with a base nutrient mix of 5-11-26 and then add an equal part calcium nitrate and a 1/4 part magnesium sulfate (epsom salt).  You may also want to add potassium silicate to some crops (though I have yet to try this, but Paul Cilia from Hot N' Humid likes it) and for fruiting crops like tomatoes (especially tomatoes!) a potassium supplement from flower cluster formation through to final harvest.  Tomatoes have heavy potassium needs to prevent green shoulder and ghost wall. 
Q: What's the easiest crop to start with, and what crops are the hardest?

Any leafy green like basil or lettuce is the easiest crop to grow and has the fastest turn in your system with probably the lowest risk of failure.  As you get into fruiting crops, the time to harvest increases, as does the risk of serious problems (disease, nutrient imbalance, etc.)  Tomatoes are on the higher end of the risk spectrum, but the top spot would belong to colored bell peppers.  They take a very long time to develop color from the green fruit (3-5 weeks), and this opens a long period of time for potential problems.  This isn't a reason not to grow them, but it may be frustrating if you try them first.   I want you to be successful with your first attempt at hydro so you can enjoy continued success as you gain experience.

If you're new to hydro, I'd recommend starting with lettuce.  It grows fast, it's got a high density, and it's pretty easy.  Basil is the second choice, however, downy mildew of basil is a huge problem and I've seen it wipe out entire greenhouses, so keep that in mind.  Definitely consider something like this if you want to do basil:
  There are more varieties in the pipeline, so the selection should grow in the coming years. 

You can turn both of those crops pretty fast, and you can stagger them for a continuous harvest.  I've found basil can be done as fast as lettuce if you use cuttings from your established crop for the next round.  It cuts 2-3 weeks off the harvest time, and it roots very easily. 

Hopefully this answers some of your questions.
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