Raised Sand (Plunge) bed preparation - examples?

[janemcgary]

Here are the beds in my bulb house (roofed, sides only screened), with plunged pots. The plunge material is coarse sand and used seed-sowing soil from ungerminated pots.

[Uli]

This is very interesting indeed.
But I do not understand the wire mesh placed on top of the pots. Will the plants grow through it? Will you remove it before the bulbs start to grow? It will not be possible to remove the mesh during growth and there will be no access to the pots.
I also cover my seed trays with a similar mesh to keep the birds out. But I once had a whole tray of Cyclamen seed covered with mesh and I forgot to remove it when the seed was sprouting before the leaves would be growing through the mesh. Some leaves got caught in the mesh and remained crippled. Impossible to do some weeding and no access to the tubers during growth. Only after the foliage had died down I could remove the mesh.

[Uli]

Hello Jane,
Very impressive collection! Thank you for sharing. It looks as if the plunge is on the ground kept in place with concrete blocks, right?
Do you have a kind of path in the middle of the pots? And the sides of the bulb house are covered with mesh to keep animals out, right?

[gastil]

Hi Janet, as Uli mentioned, you will want to either raise or remove the wire screen as bulb leaves begin to poke through. I've made the mistake of leaving wire mesh over bulb beds. You and I likely share a population of critters, both being in coastal California. I've got scrub jays, possums, skunks, mice and neighbor's kids' soccer balls. 

A few strategies I've used: 
Scrub jays are best kept out with bird netting, but wire mesh also works if small enough. Bird netting can be draped over a frame that allows me access. Small pieces of bird netting are enough to discourage jays. My guess is they've developed a deep fear of the stuff.

That fear strategy seems to work for wire mesh and mammal pests as well. Just a scrap of wire mesh over, or even around, bulb pots seems to scare away the kinds of critters who may have evolved to avoid wire traps. It does not work for soccer balls.

Jane's screen house was the inspiration for my own screen house. Mine is nowhere near hers in durability or aesthetics, but was cheap to build. I put three DIY wire shelf sets in a U, sharing corner poles. Then I draped the whole thing in bird netting. This lets rain and sun through, except when I top it with a tarp. It does not let birds through. And the mammals have not attempted to jump up to the first shelf, which is about 18" above ground. The mesh is open enough for most pollinators, although occasionally butterflies get trapped. 

My wire-shelf screen house is not as good for pots as the plunge. The white baskets hold tiny seed pots plunged into perlite or sand. I call them my "mini plunge baskets". Various boards or slates shade the sides of some pots from sun. I like having pots at eye level. 

I'm working on refurbishing the hoops over my plastic-board plunge beds. I have not yet decided on wire mesh or bird netting to drape over the hoops. As Uli mentions, access to the pots is important. Yours might be clean but mine always need a lot of tedious weeding by hand. 

[janemcgary]

To answer Uli's questions about the plunge beds in my bulb house: Yes, the beds are surrounded by concrete blocks. I chose the kind with a textured face for looks, and they are two large blocks high, set on a concrete base. The planting area has heavy-duty woven groundcloth on the bottom to keep moles out. The roof is double-walled polycarbonate panels, and the sides are what we call "hardware cloth" in the USA. I had to have all the metal parts painted brown because the county told me that any added structure over 500 square feet (this is 800) had to be made of "the same materials as the dwelling," i.e. brown brick, which would not have actually worked. We compromised on the paint, but I had to argue a lot and get letters of support from botanist friends. I also had to install an 1100-gallon rainwater tank and a bioswale (aka weed sink) to handle the runoff. Yes, it was expensive, but after many years fighting with cold frames in freezing weather and howling winds, I went for the over-engineered option. The temperature inside the bulb house is no more than one or two degrees warmer than ambient, but keeping the foliage dry in winter increases resistance to freezing. and yes, the side that is all pots has a path down the middle so I can reach all the pots. The other side is only about one-quarter pots at the front, and the rest directly planted larger geophytes. This summer I added more organic matter to the directly planted area.