Our food-growing spaces allow us to grow healthy produce, connect with Nature, and hopefully save money. They are also a solid response to climate change and COVID.
My blog articles this year will be about climate-resilient food gardening. Each month I’ll address one or more aspects of how climate change is affecting our food gardens and changes we can make to reduce global warming and ensure a future of healthy harvests.
HGIC has a new Climate-Resilient Gardening section (thanks to Christa Carignan!) where you’ll find more information on these topics. We plan to continually update content and add new pages. And please check out the University of Maryland Extension’s new Healthy Garden, Healthy You project that connects food gardening and human health.
This first installment includes an overview of how our mid-Atlantic climate is changing and a look at heat-tolerant crops and cultivars. Future articles will explore low-dig soil prep, composting food scraps, peat alternatives, heat stress in plants, reducing plastics, and “hardening” our garden spaces.
Resiliency is mentioned a lot with respect to climate change. A climate-resilient garden can both withstand and recover from warmer, more extreme weather. Resiliency can also mean transforming how we grow food by creating and sharing a community knowledgebase of new ideas and techniques.
Farmers and gardeners learn much by daily tending soils and plants. But the winter “off-season” affords us time to dig deeper into topics of interest and learn from co-cultivators and experts in the field. I spent some time in a variety of grower meetings, conferences, and webinars in January and February where research findings were shared. Many gardeners are interested in growing blueberry so in this article I’ll share tips for success including some insights I picked up from presentations by Oregon blueberry researchers David Bryla, Ph.D. (USDA) and Bernadine Strik, Ph.D. (Oregon State U.)
Highbush blueberry plants evolved to grow in low pH, high organic matter sandy soils with high water tables. These soils contain more ammonium nitrogen than nitrate nitrogen, hence blueberry’s preference for the ammonium form of plant-available nitrogen. The shallow, fibrous root system grows almost entirely in the top 12 inches of soil. Most of the roots are very fine, the width of a human hair, and can’t penetrate or thrive in clayey, compacted soils. The key to success is create garden conditions that mimic those in blueberry’s natural environment.
Blueberry thrives in well-drained, porous soils, high in organic matter (4% – 20%). The soil pH should be in the 4.5-5.5 range.
Soil preparation starts in fall
Begin by testing the soil in the late summer or fall prior to spring planting. For gardeners, soil testing labs provide the most accurate pH measurement of your soil, as well as baseline information on organic matter and nutrient levels. pH probes sold to gardeners are generally inaccurate and pH color kits using litmus paper are only accurate to ½ of a pH unit (5.5, 6.0, 6.5, 7.0, etc.
Add organic matter
The top 12 inches of soil should be one-third to one-half organic matter by volume. Peat moss (3.0-4.5 pH), plant-based compost (7.0-7.5 pH), and lightweight potting soil, a.k.a. soilless growing media (5.5-6.5 pH) are the materials most often mixed into the soil. Research has shown that adding compost (especially animal manure compost) can increase soil pH.
Some Oregon growers incorporate 2-3 inches of aged softwood sawdust into topsoil prior to planting. The benefit is that sawdust has a low pH, decomposes slowly, and increases organic matter levels. For Maryland gardeners, large amounts of sawdust are difficult to come by, but bark fines are readily available. You would need to apply 1.0 lb. of additional ammonium sulfate (21-0-0) per 100 sq. ft. nitrogen for the soil microbes that slowly decompose the bark fines.
Lower soil pH
Elemental sulfur is applied (based on soil test results) in the fall prior to spring planting, and incorporated to a 6-8 inch depth.
Pelletized and prilled forms of sulfur are easier to apply than powdered sulfur but take longer to lower soil pH.
An oxidation process, driven by special soil bacteria, converts the sulfur to sulfuric acid, releasing hydrogen ions that lower soil pH. The bacteria are most active in warm, moist soils. The process takes 6-12 months. Iron sulfate can also be used to lower soil pH but 6 times as much is required, increasing the cost.
Re-test soil pH to monitor pH levels and apply sulfur as needed to maintain the 4.5-5.5 range.
For container blueberry plants, mix 3 TBS. of sulfur into the top few inches of growing media, for a 15-gallon container, to reduce the pH by one unit (e.g. from 7.0 to 6.0).
Ammonium sulfate fertilizer is recommended because it supplies nitrogen in the ammonium form and helps acidify the soil.
Fertilize at full bloom and again three weeks later.
Urea is another good nitrogen source, recommended when soil pH is below 5.0 because it is only one-half as acidifying as ammonium sulfate. The nitrogen in urea is converted to ammonia and then to ammonium.
Oregon research studies show that feathermeal (12-1-0.5) and soluble fish fertilizers (4-1-5) work well in organic blueberry production. Organic growers prefer to inject fertilizers into irrigation water, known as “fertigation.” Another interesting finding was that there were no significant yield differences between the lowest (20 lbs./acre) and highest (240 lbs./acre) nitrogen fertilization rates.
Organic matter and organic fertilizers release ammonium ions with relatively little oxidized to the nitrate form as long as soil pH is in the 4.5-5.5 range. When soil pH is >6.0 most of the nitrogen from decomposing organic matter will be converted to the nitrate form with negative effects on plant growth.
Oregon research indicates that organic acids (humic and fulvic) applied in liquid form, increase blueberry root growth while lowering soil pH.
Blueberry root systems need to be kept moist. Plants can tolerate hot weather but not drought. Water your blueberry bed thoroughly and consistently when rainfall is lacking. Soaker hoses and drip irrigation work well.
Blueberry grows and produces best when the pH of irrigation water is <7.0. Commercial growers often acidify irrigation water to maintain low soil pH. The pH of municipal water in our region is typically 7.5-7.8 and has a high salts and bicarbonate content. Just be aware that your irrigation water can drive up soil pH.
Blueberry roots cannot compete very well with weeds for nutrients and water. Mulch is essential to keep soil cool, improve water infiltration, conserve soil moisture, reduce weeds, and increase organic matter.
Use aged wood chips (never fresh), shredded bark, pine needles, or sawdust as a mulch. These materials are low in pH (4.5-5.2) and salts, and decompose slowly.
Interestingly, a recommended growing system in Oregon uses strips of heavy-duty weed barrier to cover beds after they have been mulched to further reduce weed growth and moisture loss.
A well-planned and maintained blueberry bed can produce well for 20+ years. Start yours in 2021!
So let’s get this season started as soon as possible with cool-season crops. These are the plants adapted to grow best with cooler daytime temperatures, 65⁰ F-75⁰ F, compared to warm-season crops like tomato and chile pepper. They are planted in Maryland from early March through mid-May and again from July through September. Thinking about these crops in January gives us time to plan and prepare for success!
Some cool-season crops are hardy, very frost-tolerant, like pea, spinach, and onion. Others are semi-hardy, more easily injured by cold temperatures, like beet, carrot, and lettuce (although this depends a lot on cultivar, stage of development, and growing conditions). Cool-season crops germinate at lower soil temperatures (40⁰F-45⁰F) than warm-season crops like cucumber and squash (55⁰F-60⁰F).
Some cool-season crops need both cool and warm temperatures. Onion and garlic need cool temperatures for rapid leaf growth, and warm temperatures for bulb enlargement. Leafy greens grow well in spring and fall while broccoli and cauliflower tend to produce better yields and higher quality heads in fall. That’s because leaf and root growth is favored by warm temperatures and head development is best with cooler weather.
We’re mostly interested in eating the leaves, stems, and storage roots of cool-season crops. Cool temperatures cause these crops to produce more sugars which makes them more cold-tolerant and better tasting. Rising temperatures can reduce crop quality, causing bitter or off-flavors, and force plants to send up flower stalks and produce seeds (bolting). Increasing daylength may also induce bolting in lettuce, spinach, radish, potato, and carrot.
A few cool-season crops are perennials (rhubarb, horseradish, and asparagus) but most are grown as annuals, even though many are biennials.
Most commonly-grown cool-season annual crops by plant family:
Bean family (Fabaceae)- garden pea, fava bean
Cabbage family (Brassicaceae)- radish, broccoli, cabbage, Brussels sprouts, cauliflower, kale, mustard, turnip, collard, kohlrabi, Asian greens, Chinese cabbage, rutabaga, arugula
Garlic family (Amaryllidaceae)- garlic, leek, onion, shallot,
Beet family (Amaranthaceae)- spinach, beet, Swiss chard
Carrot family (Apiaceae)- carrot, parsnip, celery, celeriac
Lettuce family (Asteraceae)- lettuce, endive, escarole, radicchio
Seeds or transplants– most gardeners plant cabbage, broccoli, cauliflower, and Brussels sprout transplants but sow seeds directly in the garden for all other cool-season crops. This year, try growing or buying transplants instead. Even peas can be started indoors under fluorescent or LED lights.
Growing lettuce, kale, pea, arugula, etc. for just 2-3 weeks indoors will give you a head start on the growing season and eliminate the need for thinning excess plants (tedious!). Transplants are also less likely than seeds to be washed away in a storm. Even carrot and beet can be transplanted as long as the tap root doesn’t hit the bottom of the container while growing indoors.
Soil preparation and nutrients– it’s possible to plant and grow warm-season crops, like tomato and squash, in cloddy, clayey soil. The same is not true for most cool-season crops. Whether you plant seeds or transplants the topsoil should be loose, well-aerated, and high in organic matter. Heavy, cloddy soil slows seed germination and restricts root growth.
Preparing a bed in spring requires minimal tillage- cutting winter annual weeds at the soil with a weeding tool, fluffing the soil with a garden fork, and raking the soil smooth. If a cover crop is in place, cut it to the ground with a string trimmer, cover the area with a tarp or weed barrier for 2-3 weeks, remove it and plant through the cover crop residues.
The majority of cool-season crops have a medium to high requirement for nutrients. Fertilize seedlings and transplants in spring with a soluble fertilizer to get them off to fast, strong start. Nutrient release from soil organic matter is low at this time and root systems are too small to adequately mine the soil for nutrients may be inadequate. Fertilize fall crops once they are established.
If the soil is not suitable, plant in containers filled with a mixture of compost and soilless growing media (lightweight “potting soil”).
Protection– climate change is giving us a longer fall season allowing big harvests of cool-season crops into December. But climate change is also making spring weather even more unpredictable than “normal.” The average last frost date is earlier but seedlings and transplants are subject to wide temperature swings, excessive rainfall, and late freezes (as we saw in 2020).
Floating row covers and cold frames provide a buffer against unfavorable and rapidly changing weather conditions. They allow us to extend the gardening season so that we can plant earlier, harvest latter, exclude insect pests, and increase yields. Protective covers, whether, glass, clear plastic, or polyester fabrics, increase the air temperature around plants and reduce damage from wind and driving rainfall.
Timing– planting calendars are helpful but planting decisions should also be based on the 7-day forecast. Transplants give you some added flexibility as they can be set out earlier or held back depending on conditions. The key is to have all the pieces in place- seeds or transplants, prepared soil, protection, and fertilizer- when conditions are right for planting. Some years you may find yourself planting with a headlamp or flashlight!
Future articles will focus on planting and caring for specific cool-season and warm-season crops, and how to extend the gardening season and adapt to climate change.
COVID-19 has been devastating for poor people and people of color. Systemic racism and economic inequality have resulted in higher death rates for Black and Hispanic people. Food insecurity is twice as likely to affect Black and Hispanic households as White households and the Maryland Food Bank estimates that one in seven of our state’s children suffers from food insecurity.
As individuals we can volunteer for community kitchens and food banks, donate produce from our gardens, support local farmers, and learn about the root causes of these problems and disparities. We can also support the awesome groups that are educating, organizing, and growing food to address food apartheid and food insecurity. Here are a few outstanding examples with Baltimore roots:
Our mission: The Black Church Food Security Network (BCFSN) utilizes an asset-based approach in organizing and linking the vast resources of historically African American congregations in rural and urban communities to advance food and land sovereignty.
The Black Farmer Directory was created by BCFSN to connect Black Farmers to African American churches, other faith-based institutions, and all who wish to support them.
This fund is a special project of the Farm Alliance of Baltimore and supports 10 Black-owned farms and Black-led food and farming organizations in Baltimore.
Denzel Mitchell, Deputy Director for the Alliance, says “2020 has been stressful but work has ramped up. On top of organizing and assisting farmers we’re dealing with racial tensions and pandemic issues. How do we help farms succeed and how do we move as an organization in this current climate of fear and anxiety?”
He noted that the City has provided support for the Alliance and donors helped get the Resilience Fund started mid-year. Farmers in need receive cash assistance, tools, and equipment.
Great Kids Farm is a 33-acre educational farm operated by Baltimore City Public Schools’ Office of Food and Nutrition Services. The farm is home to goats, chickens, turkeys, sheep and a lot of veggies and fruit.
In the 2020/2021 school year, we are offering virtual field trips for any Baltimore City Public Schools’ class (http://Bit.ly/GKFfacetime ), a pre-recorded virtual program for 2nd grade students (http://Bit.ly/virtualGKF), and agriculture-based activity kits for students to gain hands on experience in their own homes. Great Kids Farm also offers youth employment to high school students, and we are looking forward to hosting our 2nd annual African American Foodways Summit for high school students this February (a virtual event). For more on our programs, contact: firstname.lastname@example.org.
Do you have gardening supplies and tools to donate or would you like to become a volunteer? Contact email@example.com
Late fall feels like a bridge between growing seasons. Walking in my garden I love to feel the earth and see the big and small day-to-day changes. I also think about the ups and downs of the 2020 growing season and what I’d like to change in the coming spring. The pandemic and the social, political, and economic turmoil have made me even more certain of the specialness of food gardening spaces. They feed people and connect us to the land and each other. Here are some chores, tips, and thoughts for this time of year:
Prep areas for planting small fruits, like blueberry, gooseberry, and blackberry in early spring. Soil testing is especially important if it’s a new bed or if you are growing blueberry and need to lower the soil pH. Cover turf and weeds with cardboard, compost, and mulched leaves to create new beds. Research the types and cultivars of small fruit plants you are considering.
It’s too late to plant cover crops. Instead, protect exposed soil with a thick layer of tree leaves (preferably mulched or shredded leaves). The mulch can be pulled aside to plant in spring and then re-applied around seedlings and transplants.
Overwinter the growing mix from vegetable containers by emptying the containers on a tarp and removing leaves, roots, and other debris. Store the growing mix outside in heavy-duty black trash bags or trash cans. Re-use the growing mix next season by mixing it 50:50 with fresh soilless growing media and/or compost. Fertilize container plants as needed.
Garlic- to mulch or not to mulch? Most gardeners and many commercial growers mulch fall-planted garlic with organic mulches, like straw and chopped leaves. Mulch can prevent erosion, smother weeds, and protect young plants from heaving and extreme cold weather. But thick mulches can also slow growth in spring, reduce bulb size, and possibly improve conditions for bulb diseases and pests. There are few published studies comparing mulched and un-mulched garlic. Warming winter temperatures may be making mulch less crucial in warmer areas of Maryland.
Comment below or email me (firstname.lastname@example.org) about your experiences growing garlic with or without mulch.
Extending the season– leafy greens stop growing around November 15th when day length is less than 10 hours. But higher fall temperatures due to climate change has increased garden productivity- there are more tasty and tender leaves to harvest per square foot of garden space. Kale, spinach, mizuna, beet greens, and other semi-hardy leafy greens can be harvested into December when protected with floating row covers.
Online gardening hacks– one can get lost for hours in the world of “look no further… this is the absolute best way to ______ in your garden.” There are lots of good tips out there if you can ignore the ads and snake oil. I found a site from a small urban grower that extolled the virtues of plastic Ts for trellising plants that I happily used this year.
Reflect on the 2020 growing season: What major problems did you have? What caused them? Can they be prevented next year? Re-think crop choices and plant locations. Did I really need to grow 30 tomato plants and three kinds of eggplant that no one in my house will eat?
Grow it and give it– plan to share more of your garden with people in need. Contact local food banks and feeding programs this winter to find out how you contribute your fresh produce.
Keep on learning…
Check out the Home & Garden Information Center website pages on Food Gardening.
Food gardens are in transition in October. Cool-season crops hit their stride and cover crops replace tired warm-season crops. Rather than put the entire garden to bed we may decide to coax more food from the ground with row covers, cold frames, and over-wintering crops. Either way, fall cleanup (“garden sanitation”) and soil protection and improvement this fall help ensure a healthy and productive garden next year.
Remove stakes, trellises, hoses, temporary fences, plant labels, and other gardening materials.
Clean up and remove all above-ground plant residues. Many diseases can survive over the winter on small pieces of leaves and stems. Some pest insects will hunker down under protective layers of dead weeds and crop debris. Either bag up and dispose of these plant wastes or compost them. All parts of the bin or pile must heat up to >140⁰ F. to kill plant pathogens and weed seeds. (Japanese stiltgrass should be bagged up with regular trash for landfill disposal.)
Empty the growing media from container gardens and store it in a trash can or heavy-duty trash bags. Soil-less growing media and compost lose nutrients and break down physically over time. Mix last year’s growing media 50:50 with fresh growing media and/or compost next year.
Soil Protection and Improvement Tips:
Instead of pulling plants out of the ground, cut them off at ground level leaving the root system intact. This reduces soil disturbance while adding organic matter.
Don’t leave the soil bare. Cover it with shredded leaves or some other type of mulch to prevent erosion. Rake leaves into a loose pile and mow over them with a lawnmower to cut them up. They will be much less likely to blow away if they are broken up. The leaves will reduce weed growth and can be retained as mulch next spring.
It’s getting late for planting cover crops. If you have seed, you can take a chance on sowing before the end of October. The soil temperature should be at least 45⁰ F. to 50⁰ F. for germination of cover crop seed. You can enter your zip code to learn the approximate temperature of soil in your area.
As much as possible, use organic matter generated from your yard and household. Organic matter brought in from outside sources carries potential risks. Manure, straw, and hay may be contaminated with long-residual phenoxy herbicides or troublesome weed species.
Invasive jumping worms have been appearing more frequently in gardens and landscapes. They are spread by the movement of soil and organic matter like mulches.
Test your soil. For $15-$20 you can have an accredited lab test your soil. You’ll get some important baseline information on soil pH, nutrient levels, and organic matter. Lead testing is included with some basic soil tests (e.g., University of Delaware). Most vegetable and fruit crops grow best in 6.0 to 6.8 pH soils. If your pH is too high or too low some nutrients may become unavailable to plants, causing deficiency symptoms, or overly abundant, causing toxicity symptoms. If recommended by the lab, you can apply lime or sulfur to your soil this fall so they can start changing soil pH.
If you like zucchini, I think you’ll love ‘Costata Romanesco.’ If you don’t like zucchini, please keep reading. It may change your life.
I became acquainted with this extraordinary summer squash many years ago, and it’s the only zucchini I plant each year. Will Bonsall, well-known Maine seed-saver, and farming/gardening guru reportedly mused that it’s “the only summer squash worth bothering with, unless you’re just thirsty.” Although its Italian name is beautiful, I will refer to it as CR to save space.
CR is a stunner with alternating dark green and light green stripes with white flecking, like ‘Cocozelle’ and some other Italian varieties. “Costata” means rib in Italian. Fruits develop 8-10 prominent ribs which give cross-cut slices a unique and fun look. It has a dry, meaty texture, not unlike eggplant, that holds up when sauteed, baked, broiled, steamed, or grilled. It has a distinctive flavor described as sweet, nutty, and earthy. In addition to shredding it for cakes and breads I find it makes the best zucchini fritters (see recipe below). This year, I’m freezing loads of shredded CR.
Tips for getting the most from CR:
This is a large plant that can easily fill a 4 ft. x 4 ft. space. Some of the sprawling stems will flop to the ground where they will root, even through an organic mulch. These additional stems increase fruiting and allow the plant to survive a squash vine borer infestation in the main stem.
Try planting in mid-June to avoid cucumber beetles and squash bugs. That strategy has worked for me if you also delay planting of cucumber and melon.
CR produces large, sturdy male flowers if you are into stuffed blossoms. Even when the fruits get overly big, 12-16 inches long and 3-4 inches in diameter, they remain tender. Larger fruits can be shredded.
A variety of bees cross-pollinate the flowers, especially squash bees and bumblebees. Plant annuals and perennials to feed bees through the growing season. Interestingly, one small Cornell University study in 2013 showed that CR was somewhat parthenocarpic (produces fruits without cross-pollination). Of 19 bagged CR flowers in the research study, 58% set marketable fruit without bee pollination.
CR is open-pollinated. With a little bit of planning seed saved this year will produce an identical crop next year (unlike hybrid cultivars).
Avoid cross-pollination with non-CR pollen by not growing any other members of Cucurbita pepo, a species that includes yellow summer, acorn, scallop, and spaghetti squash and most pumpkins. Cross-pollination may still occur if these squashes and pumpkins are growing in neighboring gardens.
If possible, save seed from multiple fruits and multiple plants. Harvest fruits when they become very large with a hardened rind that starts to turn yellow. Allow seeds to mature inside fruits for 3-4 weeks. Cut fruits open and remove, clean, and air-dry seed at room temperature. Store seeds in a sealed container in a cool, dry location. They will remain viable for 5-6 years.
Zucchini fritter recipe
2 lbs. shredded zucchini
1 medium onion finely chopped (can substitute scallions)
1 cup panko
2 tsp. salt
1 tsp. black pepper
1 ½ tsp. turmeric
1 ½ tsp. paprika
Shred the zucchini and either squeeze out excess water by hand or allow it to drain in a colander.
Mix all ingredients and shape into patties. Fry in vegetable oil until brown on both sides. Makes 15 fritters. Serve with plain yogurt.