Plant Talk

Q&A: A Patch of Potential? Try Raised Beds or the "No-Dig" Route to Better Soil

Question:

Hi, Val!  Been reading your column in the Pacific Magazine for a million years.  Thank you so much for all the gardening tidbits over the years.
 
Have a question for you - I recently moved into a one-story house that has a west facing front.  I have a potential (ha!) flower bed area.  After chatting with my new neighbours, turns out this Patch of Potential, is nothing more than clay, covered with gravel, covered with black plastic weed shield, and six inches of beauty bark.  <gak>
 
I really want a low-maintenance, drought tolerant garden here.  Tis prox 15' x 6'.  The dandelions, grass, and cotton wood tree babies have no problem growing in this area.  Is it possible for me to grow ornamental grasses and drought tolerant shubs in this environment, or do a need a mini backhoe?

Thanks,

Suki

Answer: The good news is your Patch of Potential is large enough for a mixed border, and since it faces west you should have adequate sun to grow flowering shrubs and ornamental grasses. But not with that black plastic in place...what a mess the previous owner left you!

When I was faced with nasty, weedy soil in my new garden in Langley, we laid down landscape fabric, covered it with a thick layer of gravel, and gardened on top in raised beds, a solution I've never regretted because the elevated soil warms up earlier, the beds are easy to irrigate and change out, and they introduced some topography into my flat garden...here it is, freshly installed, six years ago...

Whether you go for raised beds or not, you need to start with the soil...you'll have to pull up the black plastic, and rake out the gravel and beauty bark. Then if it were me, I'd take the no-dig route to rich, fluffy soil, which takes longer than a backhoe but is easy and effective. Here's the gist:

 Autumn is the perfect time to begin the process, and by spring your soil will be ready to plant. A supply of newspapers, a shovel, mulch and four to six months is all you need; the joy of this method is that time and nature do most of the work.

Begin by digging a shallow ditch about four inches wide and four inches deep outlining the edges of your bed. Cover the surface of the bed (sans gravel, plastic and beauty bark) with a half-inch layer of newspapers, overlapping each sheet by four to six inches, and let the edges fall down into the little ditch. Then cover the newspaper by piling up a food-deep mound of mulch, which can be leaves, grass clippings, or purchased mulch. Now you have a thick layer of mulch, trimmed with a trench, which you can ignore until spring.

 Let it all rot down for four to six months. No air or light will penetrate so the weeds will die, and the mass will shrink by more than half on its way to becoming great planting soil.

Next spring, top off the new planting area with a few inches of a feeding mulch (a mixture of bark and manure available in bulk or bags from a nursery or garden center) and you are ready to plant those shrubs and grasses into the rich, weed-free soil of your new border.

 

 

Q&A - Soil & Pruning

Question: I have a very large galvanized livestock trough that I want to use as a planter at our property in Cashmere, WA. It's about 6' long and about 3' high and deep. My question is this - Do I fill the planter with potting soil (that is A LOT of potting soil!), or do I fill bottom with something like bagged styrofoam (already have saved a bunch that I haven't run down to Ikea)/netting/something earth-friendlier and then top with potting soil? Since it is so large, can I put regular garden soil in bottom perhaps and potting soil on top layer? How did you do yours?

Thanks,

Julie MacGillis

Answer:  I hate to tell you, but to facilitate drainage you should use good potting soil - and only good potting soil - to fill your trough. And yes, it's a lot of soil, and it'll shrink some over the first few winters so be prepared to top off with a few more inches of soil each spring.

Here's the thing - if you use styrofoam noodles, or even pebbles or crummy old soil towards the bottom of your trough, when the water filters down through the soil on top and reaches a different medium it'll puddle up.   It's like you've constructed a water barrier where the two mediums meet. And soggy soil means decline and even death for most plants. I use potting soil the full depth of every one of my raised beds and troughs, on advice from WSU horticulturists, and it makes all the difference for plant health. Wish I could recommend a less expensive solution, but no go...

Question: After a January that Cliff Mass says was the warmest ever, and continuing El Nino weather, can I prune roses and hydrangeas yet? I'm itching to finish cleaning up my garden, as the bulbs are all coming up and the hellebores are in bloom. 

Thanks,

Ralph

Answer: The weather is seductive, but try to leave your hydrangeas, roses and hardy fuchsias alone for a few more weeks. They could suffer a setback if  temperatures plunged after you pruned them. Chances are the balmy weather will carry us on into spring, but why take the chance? It's isn't unusual to have a hard freeze toward the end of February, and the last frost date isn't until the second or third week of March, depending on just where you live. Take a look at photos of the snowbound east coast to remember there's more than a month of unpredictable Old Man Winter left to weather. .

Plant Docs

Night time temperatures dipping into the 40's should have warned us, but yesterday's dramatic weather was startling. Summer blew away and autumn arrived in the space of an afternoon.

Which means nitty-gritty gardening sets in, with all the tough questions about planting and soil improvement, etc. etc.....time for advice from the plant docs. Four horticulture professors have launched a blog full of practical advice. Each writes about their area of expertise, current experiments and projects...

The quartet includes Linda Chalker-Scott, professor of horticulture and landsape architecture at Washington State University (who just won an award for her book The Informed Gardener); Jeff Gilman from the University of Minnesota; Holly Scoggins from Virgina Tech; and Bert Cregg of Michigan State University. These four have spent their academic careers testing horticultural myths, drowning slugs in beer, digging up problematic roots and testing mulches - or so you gather when you read their blog. Recent posts include how to deal with contaminated soil, wrapped root balls and voles....So now you don't have to go back to school to spend some time and gain some knowledge from The Garden Professors.