Planting mix considerations for new raised bed

[largosmom]

Hi, I have a new deep raised bed that should be completed in about a week or two. I'm considering what to fill it with. Plants will be perrennials, and of course lots of hostas, and a couple of small Japanese maples. The bed sides are about 23", and I'll have crushed cravel tamped down on the bottom to keep out the voles. I also added a "fence" along the lower edge of the wall about 8-10 inches deep. I'm going to fill it about 18 inches deep and am still trying to figure out the mix. There are two local soil and mulch places, with a slightly different mix. I really want a lightweight mix with good drainage that will give my hostas a good place to grow.

Place 1 options:

Mix of compost and bark fines with sifted topsoil. Not sure the proportions and it costs about $220 per 6 yards. Supposed to be really good stuff. They also have individual components in the mix available.

Place 2 option:

Mix of mushroom compost half and half with sifted topsoil. Can also get the soil and compost separately. This is a more expensive mix.

Hybrid option:

Considering a mix of the mushroom compost with barkfines, but delivery fees likely higher.

Do I need topsoil? I have three bales of potting mix and one of peat also to mix in.

Would appreciate your thoughts.

Laura

[redcrx]

Years and years and years ago I had a tiny yard and wanted to put in a triangle shaped garden in a corner. I dug out the junk that was there and then looked around for something to fill the hole. Went up to the local K-Mart and found cocoa shell mulch and peanut shell mulch. Mixed this with other soils and mulches. It was light, smelled interesting and it grew the biggest tulips I ever had. One nasty problem - some rodents also found it interesting and started digging some huge burrows.

[kaylyred]

This isn't really answering your question, I just wanted to add to what Ed said. I too love cocoa hull much--both dug in as a soil amendment and as a top mulch.

This may be just me...but I also find it seems to deter slugs. I'll get slug holes in the plants in my back bed (not mulched at all) but haven't so far in my front bed, which is mulched with cocoa hull. It also was a very good weed suppressant--I put it down only about 1 1/2" thick and had very few weeds in a new bed that probably should have been loaded with weed seeds. (Not to mention a yard that, I'm ashamed to admit, is still loaded with dandelions and the creeping charlie I just can't seem to get rid of.)

The chipmunks do dig in the cocoa hull mulch, but the jury is still out for me as to whether that has anything to do with the mulch. They seem to dig holes right up by the base of my hostas and astilbes, but I can't find any indication that they're tunneling under and eating away roots like voles. And they do this in the bed mulched with cocoa hulls as well as one mulched with shredded bark. It seems more plant-specific--there's something about the astilbes and hostas.

This year I'm buying chipmunk traps. They're getting relocated to a hosta-free woodland area.

Cocoa hull mulch can be toxic to dogs, so do be warned about that if you want to try it and happen to have four-footed furries. I use it in my front beds and let the dogs have the fenced backyard, which is cocoa-free.

[largosmom]

Funny, I just realized I have at least a bag of that cocoa mulch in my shed. I tried some in pots a couple of years ago and it mildewed, so I did not use it elsewhere. It does smell good though! I'll toss it into the upper layer.

Laura

[kaylyred]

I wouldn't use it in deep shade or anywhere where there isn't good air circulation. It did get a bit moldy for me, actually...but it wasn't anything a rake couldn't fluff away. Raked into the soil I think it's a decent amendment. It might be a little higher maintenance otherwise, though. Just a thought.

[jgh]

We were on a garden tour a few years back... visited the rooftop garden of a local TV affiliate - all raised beds built on the flat rooftop. The gardener was Rebecca Kolls - I think she's gone on to cable/web gardening noteriety.

Anyway, I had an embarassing moment when Sheila looked at one of the beds - all mulched in coconut hulls - and touched a dramatic fungus growth... slimey, yucky. She made the "yuck" face just as the TV "star" looked our way. We were red-faced as Rebecca made her way over to us, but she immediately won us over with her comment, something to the effect of "Isn't that just yucky! It looks good and smells good, but I'll never use that stuff again!"

I think your first mix sounds just great. I think the only addition I might make is to ask them to dump in some sand as they are filling the truck. I've done that. They typically load the truck with scoops of a front-end loader... so I ask them to toss in some sand every now and then. When the truck dumps, it mixes up the stuff. Sand will never compost, so it is the ideal way to maintain the light drainability of the bed. I'd much rather water a sandier mix than try to prevent rotting in a heavier mix.

One more thought - you might want to put a drain hole or several at the bottom of the bed into that gravel bed, so when the water gets there it can drain away, preferably into a spot that can use the water. Leaving a gap in the material and covering it with garden fabric on the inside to hold the mix in works... or some folks drill holes, or instal little sections of pvc pipe... That can prevent a lake forming in the raised bed, bad for roots and causing rapid deterioration of the walls if they are constructed of wood. This maybe isn't an issue where you live, but our spring presents us with snowmelt and spring rains, so a container, even 18" deep, can fill up and if it doesn't have drains, it can be an unwanted pond rotting out plants for too long during the cold spring weeks.

[largosmom]

I think I will toss that mulch into the bed...good way to get rid of it, lol. A bag or so mixed into several yards of fill won't have enough to mold, I think.

You have given me something to think about, a french drain in the gravel was something I had not considered, but could be done. We have done something similar in a gravel patio at a previous home. Will talk it over with hubby and see what he thinks. The "soil" is heavy clay, so it hardens up pretty fast after spring, so water may pool if I cannot slope it to the edges. We get heavy thunderstorms...and the occasional hurricane so I'd rather it drain away from the deck and house.

Thanks for the comments on mix #1. I've been thinking that direction. Got the underground fence installed along the back of the bed today and backfilled some of the trench area. I will have to till a little bit to be able to spread out enough soil to reach the bottom of all the boards. Hopefully, my part will be done next weekend. Then we'll get some help getting my pile of gravel into the bottom so that I can rake it out and tamp it down.

Thanks! Will try to post a couple more pictures as I make progress. Can't wait to get that pile of gravel off the yard!

Laura