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.

Designing and Building Raised Beds

As spring approaches, we wait in excited anticipation for delivery of our first seed catalog order, or impatiently mark off the days to our first sowing. New gardeners wonder how to best lay out their gardens to squeeze in all the vegetables from their recipes, impulse buys at the seed rack, or favorite flowers. Veteran gardeners want to manage planting schedules or crop rotation better, provide easier access, and even squeeze in a few more plants than last year. Raised beds are a great way to help organize your garden plot and improve yield.

Benefits of Raised Beds

Gardening in raised beds offers several advantages over growing in flat earth, or even mounded rows. The soil in raised beds not only drains better, preventing rot, but actually warms up sooner in the spring and stays warmer later into the fall, extending your growing season. Soil in raised beds doesn't get walked on, so it stays less compacted, improving oxygen and water flow that creates a healthier underground environment for roots and organisms.

Raised beds are more accessible to people who have a hard time bending over or squatting down to ground level. Edges of raised beds built at 15 to 19 inches high provide comfortable seating while working in the garden.

Some P-Patch locations do not allow framed raised beds, but those who are allowed to build them may enjoy their benefits.

Lengths

Beds can be any length, but standard lumber dimensions and the size of your garden plot will help you decide how long to make your beds. Most P-Patch plots are 10 feet by 20 feet. You must remember to accommodate narrow paths between your plot and your neighbor's – so you don't really get to build out to the full 10-foot or 20-foot dimensions.

Lumber is sold in a few standard lengths: 8, 10, and 12 feet are the most common. Designing your beds based on standard lengths will help reduce the number of saw cuts you must make (or pay for). Though I've built beds longer than 14 feet, transporting the lumber is challenging, and butting shorter boards end to end creates wobbly joints. I prefer to build 8-foot long beds since that doesn't require cutting down standard lumber and leaves room for paths within a 10-foot plot dimension.

Widths

Optimal raised beds are anywhere from 2 to 4 feet across. If you can only access one side, a 2-foot wide bed makes sense. That's about as wide as your kitchen counters at home. Typically you have access to all sides, where widths of 3 or 4 feet give ample access.

Four-foot wide beds only require one cut of an 8-foot board, however more than a few 4-foot wide beds don't fit nicely into a standard P-Patch plot. Some 3-foot wide beds are inevitably required, though that means two cuts of an 8-foot board. If you don't have a power saw (and don't want to spend hours with a hand saw), you can usually get a home store or lumber yard to make one cut for free, but you may end up paying for other cuts.

(For those of you paying too close attention: Yes, if you follow the construction diagram below, the outside dimension of the beds will be 3 inches wider than the short board (two 2-by widths). That doesn't really affect the general layout options at the end of this article.)

Heights

Here's where standard lumber sizes get tricky! The end measurement of a 2x8 is really 1 1/2 inches by 7 1/2 inches. A 2x10 is really 1 1/2 inches by 9 1/2 inches. A bed made with one 2x8 or 2x10 high is adequate, but doesn't provide comfortable seating. 2x10s also get quite heavy. I prefer walls made of two 2x8s high, which means I'll have a low seat at 15 inches.

The long sides of your bed will require some vertical bracing. Many folks use rebar, but pounding rebar into the ground can damage water or drainage pipes, and become obstacles that attack your knees and shins! Use one short piece of 2x4 (cut as long as your walls are high) for every 4 feet of bed length. Also use short 2x4 sections to strengthen the corners of your beds rather than just attaching the edge of one board to the end of another. You will have to make six cuts to get six 15 inch sections from a standard 2x4x8' (with a little scrap left over).

To prevent the sides from bowing out after the beds are filled with soil, you can set the beds a few inches into the ground, or nail a length of plumber's tape (that anodized metal strapping with holes) from side to side across the bottom of your bed.

Use three-inch anodized nails or deck screws to join the lumber. Use two per board at each of the positions shown below. If you use screws, pre-drill holes in the 2x8s (but don't pre-drill the 2x4s). The drill should be slightly larger than the bore of the screw you're using. I like to pre-fabricate the short sides at home since it makes the work at the garden easier.



Materials

The best lumber to build your raised beds from is Douglas fir, which will last from four to six years in the garden. Cedar is very brittle, tends to splinter easily, and doesn't stand up to garden tools well. Commonly available cedar fence boards are not strong enough to contain the weight of soil. Treated lumber contains a variety of harmful chemicals including cyanide and should never be used to build garden beds.

You will need three or six 2x8x8' boards (three for single height beds, six for double height beds) and one 2x4x8' for each individual bed you build. You will need 56 nails or screws per bed (plus a few extras to make up for those you bend or lose in the dirt.) Nails and deck screws are typically sold by the pound. A store employee can estimate how many screws or nails you'll get in a pound.

If you don't have a vehicle suitable for transporting lumber, most lumber yards offer delivery for a fee, or even free for large orders.

Sample Layouts

Here are some example plot layouts that fit a few standard raised beds into a typical 10-foot by 20-foot P-Patch plot with room left over for paths. Line your paths with a layer of compost material, wood chips, or even pavers.



Fill your newly built raised beds to a few inches from the top with soil from your garden, or mound up compost materials as high as you reasonably can to create next season's soil. No matter which direction you orient your planting beds, the old rule of planting rows in a north-south direction will still expose your plants to the maximum amount of light as the sun moves overhead.

Copyright © 2005 Brian Ballard. All rights reserved.

Build a Simple Coldframe

Spring never comes soon enough, and summer never lasts long enough! One way to extend our growing season is to use a coldframe to trap heat and shield plants from chilly winds. This lets you grow crops later into the fall, and start planting earlier in the spring.

To build a simple coldframe, you will need four six-foot cedar fence boards, about five feet of pine or cedar 2x2, 32 two-inch nails, a section of clear or translucent plastic slightly larger than three-feet by three-feet, a hammer, and a regular office stapler or staple gun.

Cut each fence board into equal three-foot halves (or ask the home store or lumber yard where you buy the boards cut them for you). Cut four 10½-inch lengths of the 2x2 with a hand saw.

The fence boards will become the walls of your coldframe. The 2x2 sections will provide a nailing surface for the ends of the fence boards. Nail the ends of two fence boards to two 2x2 sections. Stand these wall sections up, and nail two of each of the remaining fence boards to each end to form a square as shown in the photo below.











Once you have the walls of your coldframe all attached, spread the plastic across the top and staple it all around the edges of the coldframe. You may want to insert cross-brace or two just under the plastic to support it in rainy weather. I've used old sticks or bamboo for cross-braces.

Your coldframe is now ready to use. Place it over low-growing leaf crops in the fall. Place potted seeds under the coldframe to sprout, or leave it over seedlings or transplants until they're well established in the spring. On those rare sunny or warm days, you may need to prop up one edge of the coldframe with a brick so your crops don't bake. Once you're done with the coldframe, discard the plastic and break the frame down into flat sections for storage until the next time you need it.

Copyright © 2005 Brian Ballard. All rights reserved.

When Your Garden Sleeps, It Dreams

This winter it may seem nothing is happening in your garden. Biological activity slows down in the colder months, organisms go dormant or migrate deeper into the soil, cool season weeds like chickweed get their first footholds, and rains wash nutrients and important minerals away. You don’t have to be a helpless observer of this hibernation. Use the winter months to rebuild your soil.

Once your garden is done for the season, clear out the last of your annual plants saving them for compost. Reserve a small part of the garden for your fall and winter greens and for planting garlic cloves in November. Cover the rest of your soil with a nice layer of compost materials about 8-12 inches deep. Be sure to use both “greens” (grass clippings, coffee grounds, fresh chopped plants, composted manure) and “browns” (fall leaves, non-pressure treated sawdust, dry plant material) in the mix.

A variety of amendments help replenish the supply of important minerals. Agricultural lime is a good source of calcium, and dolomite lime also includes magnesium. Calcium helps plants build cell walls. Magnesium is the working ingredient in chlorophyll. Both types of lime help neutralize acidic soil, which is also a side effect of too much rain.

A compound called greensand includes a different mixture of beneficial minerals including potassium, iron, and phosphorus. It’s usually available at better garden centers.

You can even use granite dust to add a wide array of minerals to your soil. If you look closely at granite, you’ll notice it’s made up of thousands of different crystals fused together. Each crystal is essentially a different mineral, including many that plants require in tiny amounts: potassium, calcium, iron, magnesium, phosphorus, manganese, and others. These minerals become more available when ground into gravel, or even into dust, and are broken down further by organisms and naturally occurring weak acids in the soil. Ready sources of granite dust include stone yards, or gravestone monument carvers.

Spread a few handfuls of lime, greensand, or granite dust over your compost mix and work it in a bit. Water the mulch well, and cover it with two layers of burlap. The burlap works as insulation, keeping the soil and sheet mulch slightly warmer than the air, and provides the dark, moist environment soil organisms prefer. Most coffee roasters will gladly give you discarded burlap bags their raw coffee beans are shipped in.

Once or twice during the winter, pull back the burlap and turn your compost mix, covering it again with the burlap when you’re done. In the spring, you should be able to remove the burlap and either plant directly into the finished compost, or work it into your soil a bit if it’s not completely done.

Copyright © 2006 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.