The optimal soil pH for most plants is in the 6.2 to 6.8 range, that is where most soil nutrients are most readily available, so you need to get the soils pH down. Peat Moss and Vermiculite add nothing to the nutrients in soils and the only real contribution Vermiculite makes is drainage, moving water through the soil.
It can take 3 to 5 years after making a raised bed for the Soil Food Web to develop enough to feed the plants you want to grow, so if these beds have been built in the last year you wil need to keep working on getting that soil into a good, healthy condition, balancing the soils pH and nutrient levels.
In addition to a good, reliable soil test for nutrient levels and soil pH these simple soil tests may be of some help.

1. Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

The beds were built four years ago, so this is my fourth summer of using the beds. The plants grew great the first year, but not for the past three years. I'm just not sure how to adjust the soil except by adding sulfur. It seems that adding compost does nothing for the soil because I added a yard between 5 beds this year and the ph is high and the plants aren't growing. I'm at a loss as to what to do.

Did you do a soil test from a home kit or send samples off to a soil lab?

jamhar,

Your experience sounds like mine, first year decent garden after digging leaves,... into beds, then 2 years of almost no harvest.

Kimmsr suggestions are really good, what is the result of the "jar" test on your soil.

It sounds like you are just adding compost to the top of the bed, which is ok if your soil is good, but if it isn't that won't be enough.

My problem was heavy clay soil, after the first year I didn't dig it again and it just compacted so plants wouldn't grow well.

Did you dig your soil again each year? What kind of soil is it? How did you add compost? How much?

My garden is now doing great, best ever, as I switched to hugelkultur, burying logs in the ground. I believe that I won't have to till or dig next year and the beds will become no till from now on.

It is frustrating to see a good harvest one year and then bad ones after. Like drinking vinegar after tasting hot chocolate.

I posted a bunch of pictures of my garden on the link below.

Here is a link that might be useful: low cost vegetable garden

My soil test was one from the store. I added compost and I mixed it in with what soil was already there. The soil is the Mel's mix 1/3 compost, 1/3 peat moss, and 1/3 vermiculite. My question is that after I do a jar test then what do I do if it isn't good loam? I'm confused about what to do after doing the jar test.

Yep you gotta get that oh down or your plants are gonna continue having bad hair days. Once the ph gets in the fun zone they'll start growing like mad.

What you see as a result of the "jar" test will indicate how much organic matter is in your soil, although it may be somewhat interesting to see what other soil particles are present that information is not of great value. The mineral portion of soil is what you have, except in raised beds that might have imported something from somewhere.
Too much organic matter in your soil is as unwanted as too little. Your goal is to have about 6 to 8 percent organic matter in the soil.

So, I did the soil test in the jar. It looks like it's all good. I have about 1 1/4 inches of sand, 1 inch of silt, 1 inch of clay, and 1/4 inch of organic matter. I also dug a hole and filled it with water. It drained out in about 20 minutes even though the soil was damp. I held a clump of moist soil and poked it and it fell apart. I couldn't find any worms, there used to be worms, but I didn't see any. Also, it smells like regular soil. Therefore, I'm not sure what to do next to get the ph right for next spring besides adding more compost again and maybe sulfur (I've heard that will lower the ph). I just want my plants to grow and produce some vegetables.

Sulfur and peat moss are good for lowering the ph. Don't add any fertilizers with phosphorous such as bone meal. Don't add thing with a lot of calcium like egg shells. I think some manures could also increase ph. Aluminum sulfate for turning hydrangeas blue works, but can burn the plant roots.

Where are you located? Is it typical to have alkaline soils in your area?

Where are you getting your compost - do you make it yourself, or buy it? If it's composted manure, it's possible the farmer was using lime in their barns which can cause high pH in the manure and the resulting compost.

I'm in Oregon. The compost said dairy, bark, and manure so it's likely that this has caused a high ph. A friend told me to try mint compost.

If you are planning to add more organic matter, you should certainly make sure whatever you are adding is neutral pH or even slightly acidic to help your pH problem. But since you have a lot of organic matter already, I would concentrate on fixing the pH problem as a top priority.

Just yesterday I used some soluble aluminum sulfate on some acid loving plants. It said you can dissolve it in water to use for container plants as well. Since we are having drought I did that for some shrubs. 1 Tbsp per gallon. You might want to find a small bag of this and use it for watering to see if it helps your plant growth.

You can also use cheap distilled vinegar, diluted in a bucket. Only takes 1/4 cup per bucket to bring the pH down. It's probably the most temporary but since you're in the growing season, fast results are important.

Sulfur is a good idea too, but it works more slowly since it is not soluble AND has to be metabolized into acid before it does any good. Sulfur is a good thing to dig into the entire bed before planting, or in the fall after your garden is done so it can cook during the winter and hopefully adjust the pH a bit.

If anyone here has comments on the above, please chime in.

Before trying to adjust the pH I would get a professional soil test done and not depend on the home test.

My other questions would be, do you have hard water that could be affecting the pH? What are the other signs of problems in the plants beyond just not growing? Are the leaves yellow with green veins (often indicating nitrogen deficiency due to pH problems and often helped by spraying with Ironite)?