Interbay Mulch

When you put your garden to bed for the winter, that doesn't mean nothing happens during the dark, cold, or snowy months. Left bare and exposed to the elements, important nutrients will wash away, and soil organisms will go dormant or even freeze to death.

There are many ways to over-winter your garden while at the same time improving the soil for a head start next spring. One way to invest in your beds was invented at Seattle's Interbay P-Patch: Interbay Mulch.

While similar to sheet composting or Lasagna gardening, Interbay Mulch attempts to bring critters responsible for decomposition all the way to the top layer of organic matter. The full distribution of organisms makes this composting method somewhat faster than sheet composting.

Making Your Mulch

Once your beds are cleared of this season's crops, create a mix of equal parts greens (grass clippings, coffee grounds, fresh chopped plants, composted manure) and browns (fall leaves, non-pressure treated sawdust, dry plant material, etc.) just like you would for a hot compost pile. Though it's tempting to use mostly browns, thinking there's plenty of time for them to break down, be sure you add enough greens for a balanced decomposition process.

Spread your mix in a good foot-thick layer (or more if you have the stamina) on your planting beds. Water the mixture well to wet it down, then cover it all with a layer or two of burlap bags. Wet down the burlap too (or soak the bags in water before placing them). The burlap keeps the mulch dark, damp and insulated so organisms can work all the way to the top of your batch.

That's all there is to it! During the winter, check your mulch every few weeks to be sure it's still slightly damp. You might also turn your mulch at least once during the winter.

Room and Board

Gardeners have experienced a few problems with Interbay Mulch. During the chilly winter months, mice or rats sometimes set up house in the mulch as it retains a bit of warmth under the burlap blankets. If you've incorporated kitchen scraps into the mulch, rodents may not even have to go far for food! You can minimize this problem by excluding food waste from your mulch, and checking under the burlap for rodents every few weeks.

Moist burlap also provides the kind of environment slugs just love! During your occasional winter bed checks, pick out any slugs and kill them.

After a few years of experience, several gardeners at Interbay have noticed that too much organic material can cause their beds to shed water in the dry months. Interbay Mulch may not be appropriate to use every winter. Next winter, plant a cover crop where you had mulch this year. Then rotate back to mulch the year after that.

In the Spring

By the time spring rolls around, your Interbay Mulch will be finished. A few weeks before you're ready to start planting, remove the burlap and turn the beautifully decomposed mulch into the soil. You'll notice a better response from your vegetables and flowers next year as your investment this winter pays off!

More Reading

Here are two great articles about Interbay Mulch on the web. Read them for a more detailed history and additional recipes.

Interbay Mulch at GardenWeb

How to bake a batch of compost at The Christian Science Monitor

Copyright © 2003 Brian Ballard. All rights reserved.

Save Browns for Spring Composting

Just as Seattle gets too much water in winter and not enough in summer, compost materials can be difficult to balance across the seasons. Spring brings us too many "greens" while fall brings us too many "browns" for a balanced compost pile. The solution is to save some browns now to use next year's compost. Unlike "greens" which tend to get stinky if you try to store them, browns will patiently wait until you're ready for them.

When autumn leaves start falling, offer to rake your neighbor's lawn, or collect leaves from local side streets. Get your kids or grandkids into the act! Collecting leaves will be less messy if you get a head start on the rains, but even wet leaves will store fairly well.

If you have an out of the way location that won't be unsightly, store your leaves in plastic garbage bags. If not, simply pile the leaves on your garden plot after harvest time. Cover the pile with burlap weighted down with stones to keep your leaves from blowing away. You could even build a wire cage at your plot to store more leaves.

Some P-Patches make arrangements with the city to deliver leaves cleared from public streets or parks. If your P-Patch has enough room to store lots of extra leaves, contact the P-Patch office about setting up delivery.

When spring finally rolls around, mix your saved leaves with fresh grass clippings, coffee grounds, and other "greens" to start a batch of compost. If you keep the leaves a year or more, they'll eventually break down into great "leaf mold" that you can use to start seedlings or to mulch your garden. Don't let the word "mold" scare you – that's just the term for old leaves that have broken down to the consistency of soil.

Copyright © 2004 Brian Ballard. All rights reserved.

Preparing Your Garden for Winter

In a few months, you'll be putting your beds to bed for the winter. But that doesn't mean nothing happens during our dark, rainy months. Left bare and exposed to the elements, important nutrients will wash away, and soil organisms will go dormant or even freeze to death.

There are many ways to over-winter your garden while at the same time improving the soil for a head start next spring. Here are three suggestions that you may want to try (or even try each suggestion in a 3-year cycle.)

A Variation on Sheet Composting: Interbay Mulch

Once your beds are cleared of this season's crops, create a mix of equal parts "greens" (grass clippings, coffee grounds, fresh chopped plants, composted manure) and "browns" (fall leaves, non-pressure treated sawdust, dry plant material, etc.) just like you would for a normal compost pile.

Spread your mix in a good 12-18 inch layer on your planting beds. Wet down the mixture well and then cover it all with a layer or two of burlap bags. The burlap keeps the mulch dark, damp and insulated so organisms can work all the way to the top of your compost material. You can pick up free burlap bags on Wednesdays and Fridays at the Tully's loading dock at the south end of their building on Airport Way (the old Rainier brewery).

This winter, check your mulch every few weeks to be sure it's still slightly damp (and that rodents aren't using it as a home). Turn the mulch once on a rare sunny January day to help even out decomposition. By the time spring rolls around, your Interbay Mulch will be finished. A few weeks before you're ready to start planting, remove the burlap and turn your beautifully decomposed mulch into the soil.

Cover Crops

Winter cover crops benefit your soil as they grow and when you turn them under in the spring.

There are basically two types of cover crops: legumes that add nitrogen, and grasses that break up compacted soils and mine minerals from deep down. Nitrogen-fixing plants like crimson clover, vetch, field peas, or fava beans will help capture nitrogen from the air. Cereal rye, winter wheat or other grasses won't capture nitrogen as well as legumes, but their long fibrous roots help break up heavy clay soils. Grasses also mine essential minerals from deep down in the soil where other plant roots don't normally reach. Interplant grasses with legumes to help support the sprawling habit of vetch or field peas.

Plant your winter cover crops now. Better nurseries will a selection of seed mixes. You should even sow cover crops amongst any plants you haven't harvested yet. In May, turn your cover crop under several weeks before you're ready to start spring planting.

Winter Gardening

There are many crops that flourish in the cooler weather of fall, or even prefer a good chilly winter to get a head start on spring. You can start lettuce, arugula, cabbage, mustard, radish, beets, and snow peas now for late fall harvest. Try a cold frame or cloche for continuous harvests of greens through all but the most severe Seattle winter. October is the time to plant garlic or shallots to give their root systems to prepare for spring growth.

Copyright © 2004 Brian Ballard. All rights reserved.