In my desire to squeeze more figs onto my property I'm looking at planting in places that aren't ideal.  I already have a few in 3 hours of sun.

Where my septic line runs does get good sun, so I'm thinking of putting containers there.

But I don't want to root prune, lug them around, so I want very large containers that are more or less permanent, and just add more compost yearly as the soil level drops.

What size would accomplish this?  

Thanks 

 

Don,

Three hours of Central Texas sun is like full day sun in many other parts of the country.  For this reason, what works for others might not necessarily work for you.

I'm not sure I would recommend putting a container (of any size) in full central Texas sun.  You might want to consider a thick concrete container for its insulating properties.  Also, it is important to remember moisture is not evenly distributed through a container.  More water is held in the bottom and gradually less is held as one moves up the container.  If you use a heavy mix much of the bottom of the container will be to saturated with water to allow roots to grow.  This effectively reduces the size of the container.  Too loose of a mix and you end up using an excessive amount of water to keep moisture in the root zone.

Do you have room near (lets say maybe 10' on either side) the septic line to plant?

I think that the most sun I have  is 6-7 hours in that spot.  I was thinking of concrete block 2-2.5 deep and 4'x4' with bottom lined with a few layers of some long lasting weed barrier, your right, the mix would have to be well drained and balanced.  Compost and sand perhaps

I saw pictures on the web of some very large potted figs, but I have no idea if the roots were allowed to grow into the ground, I'll see if I can re find them.

I could plant them 10' away.  Do you think that is far enough away to avoid the roots growing into the septic line?

Twenty feet (10' on either side) should be enough space for equipment to come in should you need the septic system maintained/replaced and not disturb the trees. There are two ways to keep roots away from the pipes. If you have access to cultivator, run it between the trees and the septic line every few years. I ran one less than 3' from my trees to breakup the weeds without a noticeable effect on the trees. Another option would be to dig around the pipe, lay down a layer or two or three, then fill with rocks.