As my area begins to emerge from a late winter, I've noticed the grass and clover around the edges of my compost bin is already a deep rich green and it is growing enormous by comparison to the yellow, still-dormant grass everywhere else. The leachate coming out the bottom holes is working wonders, and I'd hate to waste that. As the west-facing side of the compost bin is also going downhill, it's the perfect spot for something, and it would provide some shade in the afternoon for the bin to keep the worms alive.
I'm thinking about planting a nice medium-sized perennial, and I wanted to hear what people think would make good candidates! I hear American Elderberry is an excellent companion for compost (and I'm thinking about knocking the bottom out of my bin, which means the Elderberry could interact with its soil), but I worry that it would spread out too far and gobble up the space between my fence and my first hugelbeet.
A dwarf fruit tree would grow straight up and not spread out, but they say that overrich soil is bad for fruit production.
What's the best perennial to put there to exploit that glorious compost leachate?
I know you said perennial, but maybe you could consider a "hungry" annual such as squash or tomatoes, or a herbaceous perennial such as asparagus or rhubarb. Though I believe a lot of shrubby/woody plants would benefit from the compost, they will most likely thrive anyway. The herbaceous plants, especially ones your harvest a significant portion of, like asparagus, would benefit more, in my opinion.
While perennials would certainly do well in the area you describe, it would be more advantageous to plant as Galadriel suggested. Squashes, tomatoes, in fact most of the vegetables will produce greater quantities of produce, giving you the biggest rewards.
As you stated, Elderberry would do very well, to the point of taking over, through root spread propagation, to encompass the entire area. I have seen this happen at a Commercial Nursery site.
Grapes would also benefit from that space.
Figs would also be a good perennial to plant, they would spread out and provide shade, and they would fruit very well.
I thought figs needed to have their roots restricted to fruit well, so suspect that planting one in such a rich site would result in lots of lush growth and not much fruit? But I like the idea of planting something less hardy that could benefit from the heat reservoir of a compost heap next to it. It depends how your heap is constructed maybe, but I might vote for the grape, or a kiwi, or a Myrtus ugni.
I have heard all manner of miss-information about growing fig trees over the years.
One of the worst is the "Figs need poor soil to thrive" myth. It just isn't true. Figs like good soil with good drainage (they don't like wet feet).
The myth you mention, about needing restricted roots to fruit is also not a new one to me. This myth came about from the Potted Fig trees sold in many areas.
Somehow the root bound myth got going, probably because fig trees fruit well when container grown, but if that same fig tree were to be planted in the ground, with plenty of root room, it would continue to put off nice crops of figs, year after year.
Another one is that fig trees need lots of care, once again it just isn't so.
When it comes to fig tree care, you should know that growing fig trees requires well-drained and fertile soil.
The best soil for growing fig trees would be loamy soil that has plenty of organic matter cut through it.
Also, be sure the area gets plenty of moisture. The perfect pH for growing fig trees is a soil pH of 6.0 to 6.5.
When thinking about how to grow figs, you should know that they should be protected from cold winter winds and direct winter sunlight.
Unseasonably warm temperatures can cause your fig trees to grow.
If this happens too early in the season, and then another freeze sneaks in, your growing fig trees will be damaged.
For good fig tree care, remember that a northern exposure keeps your fig trees dormant until the time comes that they should be blooming.
You can set your dormant, bare-rooted trees out in late fall to early spring.
For easy fig tree maintenance, you should choose fig trees that are free of root-knot nematodes.
Fig tree maintenance is not a lot of work.
Fig trees like full sunlight and adequate room for growth.
You can plant your growing fig trees about 15 to 20 feet apart.
If you are going to train your trees to be bushes instead, plant them 10 feet apart. Either way, there is little fig tree care you will have to administer.
Be careful not to have too much nitrogen in the soil.
Excess N will cause bolting, branches will get to long and break under the weight of the fruit.
It can also cause trees to grow so fast that they become weak overall and this can lead to splitting of the trunks.
You can fertilize the soil at a rate of one pound of 8-8-8 each year of age of the tree, or each foot tall the tree is.
This is to a maximum of 12 pounds and then you would maintain the same rate each year.
With regard to fig tree maintenance, you should fertilize your fig trees annually.
If you have heavy soil, fertilize the tree when the buds swell.
If you have loamy soil, you can fertilize with half the amount required when the buds swell and the other half can go down in late May.
Good fig tree care requires some pruning.
However, fig trees don’t require much pruning, just the dead wood and crossing branch removal/reduction is plenty.
You should prune in late winter just before growth begins so you don’t injure the plant.
Harvesting your figs can be done as soon as the fruit is softening.
Figs are not tasty until they are ripe, so you will need to let them stay on the tree until fully ripe.
Figs will stop ripening once they are removed from the tree.
You can store them in the refrigerator for a week or two until you are ready to use them in recipes or eat them.