I THINK oaks have deep tap roots, rather than invasive roots like a lot of other trees.

Maybe you could plant some shallow-rooted annuals over it, but I wouldn't plant perennials. Some have deep root systems. Besides, you might have to dig up the septic some day, and you would ruin your flower bed.

You might call a septic cleaner service and ask them about it. The usual rule is to plant nothing but grass over it, but there might be exceptions.

Sue

Read this for some basic advice.

Here is a link that might be useful: VA Tech extension on planting septic fields

One option might be to make a patio with pavers over it and have potted plants. Your plants wouldn't be disturbed that way and the pavers could be put back if it had to be dug up.

I do......{{gwi:656742}}
and I hope it works out well!

Someone I know planted a field of lavender over their septic field. It looks like a very large raised bed with stones around the edges. It looks very lovely.

If you do have to have the septic tank pumped I would plan on doing it in the spring or fall so that you could dig up the plants and then replant immediately after.

Heidi

I recently had my septic tank dredged and the opening is about 2 feet beneath the surface. When I purchased the house the inspector wasn't quite sure where the tank was so they had to do some exploring. When they dug into my yard to reach the tank it left about a 2 ft x 2 ft bare spot in the grass. Rather than replant grass over the bare spot I chose instead to create a circular design of river rocks to mark the opening for future reference. If the tank had been located in an area where I needed to plant, I would have felt comfortable planting perennials with the understanding that they would have to be dug up every 5 years or so for a tank cleaning.(A foot of soil is more than sufficient for perennials to thrive) And annuals would be easy on top of the site. I would be concerned about planting things with deep taproots-- these tend to be your monocots like grasses and milkweed-- not because they would wreck your tank but because these plants might not survive a transplant after your next dredge. Most oaks have deep roots -- I believe Pin Oaks have shallow roots. I'd leave your oak alone for the time being and let the septic guys come back to you with a recommendation as to whether or not the roots could damage your tank. There is probably a way for you to do some selective oak root pruning without putting the oak at jeopardy. I would still mark the opening of the tank with a rock or something.

The septic tank may not be the problem that the leach field is. My understanding is that the septic tank has concrete walls, whereas the leach field has pipes with holes that roots would definitely clog up. Am I wrong about this concept?
We had our septic tank cover raised so that it sits just above the ground. I can plant annuals or perrenials around it, or place potted plants on top of the cover. The flowers won't get destroyed and the septic tank cleaner doesn't charge me for digging up the heavy concrete cover every 2-3 years.
I would like to know what can be planted on the leach field, besides grass, as the weeds are really a problem. Is vinca minor deep rooted? Any suggestions?

I was hopping to put a succulant garden on the septic bed is this a good idear or do they have a large root system?

I've been researching this a bit as well.
SunnyMG has the right idea.
From what I've read online (i.e. my info is only as good as the source) - it's not good to plant anything with deep roots over the leaching field. Also, you would not want to put a patio (for example) over the bed either. Found a link that may interest you:
http://admin.wildflowerfarm.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=1&Product_Code=50008
Good Luck.

Here is a link that might be useful: Option for SepticBed Garden