Yes, unless you want it to bulge out at the sides and possibly split the fabric. The weight of that volume of damp soil is rather significant............ :-)

Weed barrier is not strong enough to support the weight of that amount of soil. Why would you line the bed with weed barrier? I can't figure a purpose that would make a weed barrier the best choice. To keep the water (from watering plants) away from your brick/foundation, I would use an impermeable material such as Foundation Waterproofing Membrane along the back, the two sides and, depending on whether the ground under your pallet bed slopes away from the foundation or not, at least a part of the bottom. A staple gun will do to fasten it to the wood. Then use weed barrier or a similar material on the rest to hold the soil in. If the box is all wood, with no gaps, there is no need for the weed barrier.

This is my first time making anything like this so I wasn’t exactly sure what to put. The bottom is mostly double lined with it... should I use landscaping fabric instead?

Please make sure you don't end up with any moisture trapped between the bed and the brick, as well as under the bed. I would give the bed some breathing room all around, so you don't create a mold-friendly situation. Because once you have mold set up shop there.... *shudder*

So really what you are making is a box or planter.

Or a planter box.

It is much bigger than a planter. 20x20x50. I reinforced the sides with one 2x4 lengthwise for additional support and left the weed barrier Its purpose was to serve partially as the rest of the wall and partly as some sort of bottom for the bed. I used hugelkultur and put tree stumps and branches etc on the bottom to fill and the top foot will be good soil and compost. Should i reline with something else before planting in it? Thanks

Heather, please read the comments above -- folks have already given you some good advice there.

I think the biggest problem you have is using permeable weed cloth next to the brick wall (or even worse, just brick veneer?). This will cause mold problems down the road as moisture is absorbed by the brick and mortar, and travels on to seep into the wood framing of the house, etc. As lebotnov mentioned, you should use a waterproof membrane. Or, make sure you have enough room all around the planter to keep the wall dry all the time. It's like you are piling dirt against the wall of your house.

Why did you ask for help just to ignore sound advice?

What you have, even so far, won't be good in the long run. You will almost certainly have moisture problems between the bed and the wall. Besides mold problems, you are also looking at a bed frame that will rot. Hugelkultur and branches all rot and then occupy less space and aid your frame in rotting.. Without enough space/air flow under the bed, the frame will rot there too.

I would advise you to remove what you have done. Line the bed with waterproof membrane and put a few drainage holes only on the bottom at the front. You really only need landscape cloth to stop your soil from leaking out of the drainage holes. If you want to use up space, the best thing to use would be rocks, stones, chunks of brick or chunks of concrete with landscape cloth over top (so your soil doesn't sink into the spaces). This will allow better drainage.