Building sustainable edible gardens | Portland, OR | Independence Gardens LLC

In the Portland metro area, we are lucky. Very lucky, in fact. With the right planning and preparation, we can harvest year-round from our edible gardens. What follow are some of the pieces of information we find most crucial for planning and planting successful fall gardens.

First Frost Date

The #1 factor in planning your fall garden is the first frost date: the first day the temperature drops below freezing, causing damage to frost-tender plants. This date varies in different locations, of course, and some might say it is becoming less predictable overall. However, data collected in past years does allow us to make educated guesses. For instance, the Fall column in the following NCDC chart shows the dates at which there’s a 10%, 50%, and 90% probability that the temperature will drop below 36, 32, and 28 degrees.

According to this chart, it is 10% likely that the temperature will hit 32 degrees (a “light freeze”) by October 24, so it would be reasonable to assume October 24 as your last frost date. More advanced gardeners might want to use the 50% likelihood date (November 15), and push their luck in order to try to get a larger/longer harvest, but the higher the likelihood of hitting freezing, the higher the likelihood that you’ll lose crops to winter damage. The data tables for the rest of Oregon can be downloaded here.

Fall Factor

Not only are gardeners working to try to beat the clock before the last frost date: as fall advances and there are fewer and fewer hours of daylight, plants also grow more slowly! To account for this change, there is a formula to calculate when to plant fall crops.

# of days from seeding/transplanting to harvest (varies by variety—look on seed packet)
+  # of days from seed to transplant size (add only if you grow your own transplants)
+  “Fall Factor” (~2 weeks—accounts for slower growth during cool, short autumn days)
=  # of days to count back from first frost date to planting date

Here’s an example of how to apply the Fall Factor formula to radishes:

28 days from seeding outdoors to harvest
+  0 days from seed to transplant (since radishes are direct-seeded)
+  14 days for “Fall Factor”
=  42 days to count back from first frost date to planting date

Hardiness

Now that you know how to calculate when to plant your fall and winter veggies, you will want to know how much attention they’ll need through the season. You can start to get a good idea of the crops you’ll be able to grow into the fall and harvest through winter by checking out this basic hardiness chart.

As you can see, you can harvest tender, warm-season crops (tomatoes, corn, beans, eggplants, peppers, etc.) up till the first killing frost, then you’ll have to say goodbye and put something else in in their place. On the flip side, you can produce some hardy cool-season crops (kale, turnips, mustard, broccoli, cabbage, collards, Brussels sprouts, Jerusalem artichokes, etc.) well into the fall, while you’ll hold and harvest other hardy and semi-hardy crops (carrots, beets, onions, broccoli, cabbage, etc.) in the garden into the winter.

Crop Protection

As the hardiness chart above shows, at a certain point there are some plants you won’t be able to save. But there are many others that will stick it out in your garden through the winter. However, even the hardiest veggies may appreciate some extra protection as the weather cools and the rain starts falling.

The important thing about protecting your crops is to moderate temperature changes and protect plants from wind and excess moisture, NOT to keep them at summer temps. For your fall and winter garden plants, a little chilly is better than too hot; on a sunny day, the greenhouse effect can rapidly cook your plants! Here are some of the many ways you can protect your fall and winter veggies:

Cloche

A cloche is a mini-greenhouse, usually made with 4 mil or 6 mil plastic clipped over PVC-pipe hoops; if possible, we recommend using pliable (fresh-cut) skinny bamboo instead of PVC, unless your PVC is repurposed! Include vents on the ends of your structure to allow airflow and remove plastic to let rain in on mild days at least every other week.

Cold frame

Cold frames are semi-permanent structures, with glass or plastic on top. You’ll need to leave a cold frame open on sunny days—or better yet, for busy folks, consider investing in automatic openers that will open and close your structure for you as the temperature fluctuates. If it’s really cold, you can insulate your cold frame with straw bales or burlap sacks filled with leaves.

Mulch

Effective protection for established plants can be as simple as straw, leaves, boxes, buckets, milk jugs, pine boughs, or other material on which frost will form first (before it touches your plants). Be creative! Just make sure it minimizes the impact of raindrops falling on your plants, blocks stiff breezes, and doesn’t become a haven for pests.

Experimenting in the fall garden

Finally, it’s worth mentioning our rationale for listing such very basic information in this post, instead of charts of what to plant when. It’s because conditions vary tremendously from season to season (duh!), and also year to year—especially as global weirding progresses. We hope that providing these basic fall gardening concepts will help you figure out what works for you, and then keep improving upon your methods: that is, treat your gardening efforts as an experiment, understanding that results will vary.

Once you understand the basics, if you want to see how we apply this info and receive monthly updates on specific garden tasks, please sign up for our Newsletter.

For additional information on fall gardening, check out OSU Extension‘s Fall and Winter Vegetable Gardening in the Pacific Northwest or Seattle Tilth‘s Maritime Northwest Garden Guide.

It might be worth stating, as a start to this blog entry, that we don’t view any plant as inherently BAD. Nope, not even weeds! Weeds are just plants doing the work they were programmed to do, in conditions favorable to their survival that we’ve either actively encouraged or passively allowed to exist. However, in one way or another, the plants we call “weeds” have work to do that runs counter to our own aims.

In general, we don’t pay too much attention to innocuous weeds that are just there: they don’t bother us much. But there are two very different types of weeds that are worth watching: 1. noxious & invasive weeds, and 2. Good Weeds.

In short, invasives are non-native/introduced species that tend to be aggressive competitors for resources (think takeover weeds); and noxious weeds have a detrimental economic impact and are regulated by federal and state agencies. (Check out the Oregon Noxious Weeds Lists and Pacific Northwest’s Least Wanted List for more information about these naughty guys.) On the other side of the coin, many Good Weeds serve us well: they attract beneficial insects, point to soil characteristics, add nutrients to our gardens, and feed us. So, which ones are which?

Our own current list of most bothersome garden invaders and favorite control strategies includes the following:

Himalayan blackberry (Rubus armeniacus) This picture shows some of our Search and Rescue colleagues plowing through blackberry canes, which we (unfortunately, for many reasons) have to do quite often. To control, we recommend manual removal of canes and rootballs, then mowing—mechanical or biological!—to keep new foliage growth down & exhaust the plant.

English ivy (Hedera helix) This picture is Karen going a little crazy on the ivy-pulling front. For control, we recommend manual removal of foliage and roots; prioritizing cutting down all vines that run vertically (on which growth ivy flowers and fruits) to prevent reproduction; and using goats, when possible, to keep foliage from growing back.

Butterfly bush (Buddleja) The key to buddleja removal is trying to get it before it goes to (prolific) seed. We either do “one cut pruning”—cutting the whole thing off at ground level—and/or cut back the foliage, then do manual stump removal. Also check for seedlings in the area. This is a picture of a stump Isabel  rocked till it popped out. Would that I could post a video–funny!

Field bindweed (Convolvulus arvensis) The pretty flower looks just like morning glory, but we don’t advise ever letting the plant get established enough to flower! At that point, it will be taking over your garden… Do: remove all parts and pieces; lay black plastic over the affected area (this is called solarizing); sheet mulch thickly; and  monitor regularly, especially at edges.

On the other hand, after reflecting on our “favorite” baddies, we’re reminded of the following Good Weeds, which we are loving (albeit still deterring, if they directly compete with our intentional plantings):

Little western bittercress (Cardamine ogliosperma) Yes, this a very clever and successful spreader: it shoots seeds out of seed pods when it is disturbed. And we know gardeners who fight it hard. But you’ve gotta love it, at least a little bit: all young aboveground parts (leaves, flowers, and seed pods) are edible—they are related to & taste like spicy broccoli/mild radish.

Chickweed (Stellaria media) Chickweed is a great salad green…mmm. As with any weed (or, really, any plant at all) that you plan to eat, make sure that your chickweed was harvested from a “clean” location: no dog poop, few passing cars, not in a septic field, etc. Just observe your surroundings and be appropriately cautious, and you, too, can harvest wild dinner!

Plantain (Plantago major) Plantain is a highly adaptable plant, growing broad and narrow leaved versions of itself in rich and poor soils…and cracks in the sidewalk. It is edible fresh (young leaves) and cooked, and is also medicinal. It’s rich in calcium and magnesium; accumulates silicon, sulfur, manganese and iron; & turned under to decompose, it helps deacidify soil.

Red deadnettle (Lamium purpureum) Edible (but not particularly tasty) member of the mint family, the stem tops and leaves are fine to use. It is also attractive to pollinators and other beneficial insects: it blooms in late winter/early spring and attracts wildlife before other plants are in bloom. This is a very good thing!

White clover (Trifolium repens) In addition to mosses, clovers are probably the most widely-viewed-as-annoying spontaneous additions to lawns. But please, please put away the weed and feed! Clovers are often used as cover crops in gardens because they fix nitrogen, and are wonderful soil-builders. Clover is also attractive to beneficial insects and pollinators.

And finally, we love dandelion (Taraxacum officinale): no picture necessary, right? Dandelions are rich in beta carotene, vitamin C and vitamin A; most plant parts (not the puffy seedhead or oozy stem) are edible: a yummy coffee substitute can be made from roots, young leaves are great salad greens, and with the flowers…dandelion tea, or wine! Taproots bring up calcium, iron, and a host of other minerals from the deep soil, and the decomposing roots of dandelions produce humus. Flowering dandelions provide early spring pollen that attracts ladybugs and other beneficial insects to the garden. Almost all soils support dandelions; one that doesn’t is totally unfit for growing things. Eek.

In this season of prevalent lawn care and herbicide commercials, we hope that this short introduction to weeds we love and those we love to hate (well, just a little bit) helps to break down the idea of weeds into something much more complex and wonderful. I’m sure you have a few of your own “favorite” weeds in mind, likely in both the noxious/invasive and friendly/helpful categories. If you’re having trouble with or want to learn more about a weed that is not on our list (of which there are certainly many!), you might check out this great identification resource: Oregon State University Weed ID.

And this is still just the tip of the iceberg. There is yet more to come…

It’s spring! Even as the rain keeps coming down between the sunbreaks, we’re starting to see flowers bloom…garlic stretch to the sky…pea shoots unfurl…and weeds start to get a foothold in our overwintered gardens.

One little dandelion peeking out from behind a watering can

We did the first spring weeding in our garden a few days ago, and sheet mulched a fenceline border over the weekend. This flurry of activity came on the heels of teaching a Garden Soils and Amendments class on Tuesday, during which we identify weed observation as a soil assessment technique. And what’s more, I’ve recently been seeing neighbors harvesting weeds off the traffic medians in our neck of the woods. This combination of weed-related events has made me especially motivated right now to look closely at this remarkable category of plants.

Weeds are a funny garden phenomenon. We define as a weed anything that we don’t think belongs where it is. Can a tomato be a weed? Sure! If it (and, more than likely, a host of fellows) came back from seeds your plant dropped last year, but you really wanted to rotate your tomatoes to a new location…those volunteers can easily be considered weeds. But we tend to label certain plants “weeds” all the time, even if they’re not specifically in the wrong place. If they’re there at all, it is a problem. Or is it?

In a similar vein to the old adage “nature abhors a vacuum,” she also doesn’t take kindly to bare soil. Plants will grow wherever there isn’t anything to compete with. In the edible garden, we have to keep weeds at bay in order to keep the space ready for the bounty of edible-for-us plants that we’re going to have growing…any day now! But is there a way we can respect weeds for what they bring, even as we’re deterring their development?

In my mind, there are four main oft-overlooked beneficial functions that many so-called “weed” plants can serve in our gardens: attracting beneficial insects, giving us clues about soil conditions, adding nutrients to our gardens, and feeding us. Yes, indeed. Mysterious are the ways of the plant world…and weeds anything but just annoying. I’m on a roll, and intend to write about each of these functions in my next few blog entries.

Of course, not every weed is a friend; some of them do deserve that pejorative label. Invasive grasses, for instance, are my own current semi-nemeses…and there are some plants (English Ivy, Himalayan blackberry, and bindweed, for instance) that are in a scary category all their own (on the Noxious Weeds list).

Personally, I don’t really mind the activity of weeding: it’s a great opportunity for sipping a relaxing beverage or talking with a neighbor. But the soils class, the beginning of the weeding season, and watching others productively utilize weed plants has gotten me in the frame of mind to investigate weeds more closely. More to come…

The most basic question when it comes to edible gardening is this: What is an edible garden? Our generic answer is a little too simple: A garden with edible plants, of course! But there’s another key question lurking behind the surface of the first: Edible…for whom?

Our answer to that takes us deep into garden philosophy-land. But here’s the short and sweet version: You want to eat what you work so hard to grow, and you should certainly do so. But we recommend integrating into the “edible-for-you” garden plants that provide food and/or habitat to birds, bees, butterflies, and other creatures, too. Because if the beneficial insects and native species are well-fed, your yield from domesticated crops will be more robust, and you’ll also have more choices for harvest. Plus, the ripple effect of a well-balanced garden that feeds more than just you is a healthier ecosystem and healthier planet.

You might expect to share some of the classic edible-for-you goodies with other critters (for feeding feeding beneficial insects, think Apiaceae family members like dill, carrot, and parsley and Asteraceae family members like lettuce, sunflower, and chamomile). But in addition to sharing with them what’s primarily good for you, you can also share some of what’s primarily edible for them.

Native plants are the best way to feed native creatures: this goes for beneficial insects, which provide services like pollination and pest control and for birds and other animals, as well. Native plants are adapted to our soils and climate so they need relatively little or no watering, fertilizing, or care once established. They are generally less susceptible to common garden pests and diseases, and they attract a variety of native birds and butterflies by providing food and shelter.

Here are some of our favorite natives that are good both for you and for wildlife:

Oregon grape (Mahonia aquifolium) Berries are tart but make great preserves; young leaves can be used fresh in salads. All plant parts have medicinal properties, based in part on the high berberine content; root is especially potent, and is used as an alternative to goldenseal in herbal medicine, as goldenseal populations are threatened.

Stinging nettles (Urtica dioica) These are not easy to grow on purpose, and anyway, we wouldn’t recommend planting them where anyone–especially children or pets–will come in direct contact with them… But if you have safe and contained space to dedicate to them, they are phenomenal allies! Leaves are full of protein and vitamins A, C, iron, potassium, manganese, and calcium, and they taste like spinach (and don’t sting any longer!) when cooked. They are also beneficial for allergy sufferers and insects.

Oxalis (Oxalis oregana) Groundcover is important for providing shelter for little creatures, and oxalis (a.k.a. sourgrass or wood sorrel) is a wonderful ground cover–and it’s tasty, too! We like to eat it for a quick treat while hiking, and it is good around a garden, too. Like spinach and Swiss chard, oxalis leaves contain oxalic acid (hence the name), so eating very many leaves is not advised.

Evergreen huckleberry (Vaccinium ovatum) Huckleberries can be temperamental to grow sometimes, but they are great treats for birds (especially hummingbirds) and butterflies. They are also very tasty for people! Isabel’s great-grandma made amazing huckleberry pies; they can also be dried, and traditionally were used in combination with dried game as traveling food.

Red-flowering currant (Ribes sanguinium) Finally (for now), we have to highlight the red-flowering currant. It has one of the earliest-opening flowers in spring, and provides much-needed nectar for bees. Although these aren’t domesticated currants, their fruits can be used in preserves and wine.

Some things that are edible (for you and other creatures) are NOT good to have in the garden. One example: Himalayan blackberries. Chances are, if you have Himalayan blackberry, you didn’t put it there and don’t want it to stay. Let us know if you have any blackberry issues–we get enormous satisfaction from removing invasive species!

You can find a directory of native plant nurseries at the East Multnomah Soil and Water Conservation District (EMSWCD) website, and you can get them directly from EMSWCD  during the 10th Annual Native Plant Sale. Pre-Orders close Sunday, February 6th at 11 pm; pay for and pick up plants on Saturday, February 19th from 10 am-3 pm. If you’re on the west side of the metro area or elsewhere, check out West Multnomah Soil and Water Conservation District (WMSWCD), or your local SWCD.

Sustainable Garden Tool Party Hostesses (L-R): Barbara, Karen, Glenda, & Isabel

This past Saturday, we were delighted to collaborate with Barbara from the One Stop Sustainability Shop and Glenda from Tomboy Tools to host a sustainable garden tool party. What, you wonder, is a sustainable garden tool? Based on our conversation during the gathering, I can offer the following suggestions for the elements of a sustainable garden tool:

• You use it to do projects in a garden that will meet your needs for a long time to come without compromising the ability of other creatures to meet their needs there–that is, a sustainable garden.
• It is durable: it holds an edge, won’t rust immediately upon exposure to the elements, holds up under stress, and doesn’t wear out after a few uses. Ideally, it will last as long as your garden…and then be a good present for another gardener down the line.
• If it does bend or break, it doesn’t have to be chucked in the trash can: you (or a talented helper) can repair it.
• It fits your body. The last thing you want is to be sore after gardening. One of the neat things about Tomboy Tools tools is that they’re designed by an ergonomics expert to fit women’s bodies. Many ladies report, however, that the extra features tempt handy family members–men and women alike–to “borrow” their tools.
• Components are sourced responsibly. That goes for wooden handles, metal blades, plastic components, and any packaging. Can you tell that the brand is doing its best to utilize sustainable materials and/or minimize materials use?
• It is manufactured close to home. Here, the closest tool manufacturer I know of is Red Pig Garden Tools. Red Pig also modifies existing tools to make them fit your body, fixes broken tools, and creates custom tools to fit your unique needs. An awesome resource.
• Packaging is recycled, recyclable, limited, or nonexistent. Enough said.
• It is third-party certified. One Stop Sustainability Shop chooses to carry many different products that have been certified environment- and people-friendly by a third-party organization. I haven’t found a specific certification for garden tools…but for many other consumer products, you can check out GreenerChoices.org for info on certifiers, the meaning of different labels, and the characteristics of a strong certification.

We had a great time on Saturday, and hope that our conversation will inspire new ideas and commitments!