Discover how a kitchen garden works in a cold, challenging climate. This 29 year old garden was put back into growing vegetables for the kitchen in 2015.
Cover crops – also called green manures – have improved soil for thousands of years. We look at what one month of growth provides in an average raised bed.
Cindy and I recently visited the kitchen garden at the Forest Highlands Meadow Clubhouse. Forest Highlands was established in 1987, with the original raised bed concrete forms poured shortly afterward.
We don’t know how long they were garden beds. They were filled in and covered with sod for a children’s play area and family picnic grounds.
In 2015 the kitchen staff uncovered half of the original concrete terraced raised beds. They kept the upper part in sod, using it as a reception area for weddings or parties with 4 large raised beds.
This kitchen garden is just south of Flagstaff, AZ in a very short season climate. Some years they have less than 60 days of growing time, while others are just over 70 days.
This limits what they can grow. Creative use of existing advantages helped them be successful in their first year. The result has been a surprising amount of fresh vegetables and herbs for the kitchen.
They grow unique and unavailable varieties showing the chef’s talents with heirloom flavors.
Let’s look at some of the techniques used to create a successful kitchen garden in a challenging climate!
This uphill shot shows the concrete forms of the original stepped landscape garden beds giving way to the remains of the sod used for the children’s play area and picnic area. Four raised beds grow vegetables needing a deeper soil and host a reception area.
The raised bed soil is rich and fertile while the terraced beds need improvement. Rains left standing water in the beds on the lower right which made growing difficult this season. The staff is planting our cover crop mix to help. The mix will open up the moderate clay soil and improve drainage, soil structure and fertility.
The terracing is harder to see from this angle, but the size of the raised beds is clearer. Each raised bed is about three feet deep, giving plenty of water drainage and depth for root crops.
The semi-intensive planting has gone well with a successful harvest considering it is the first full year of growing there.
The concrete retaining wall topped with solid fencing is at the far end of the garden, providing wind protection as well as shelter from hungry critters ranging from rabbits to deer.
Carrots, beets and radishes are growing in this raised bed. After harvest the bed is mulched with straw and left dormant until early spring. The mulch protects the soil from temperature extremes, allowing earthworms to be more active.
The raised beds are full of earthworm activity. If you create the proper environment the earthworms will appear!
This left side view shows how different the soils are just 10 feet apart from the right side. The growth is lush and full, unlike the right side beds holding water with struggling plants.
There may only be 2 – 3 weeks of growth for our Garden Cover Up Mix before the frosts kill them. This is enough time to establish a root system and mulch cover, starting improvement for the soil.
Next season they will interplant cover crops among the root vegetables. The cover crops go in once the vegetables are a month old so they don’t compete with each other. This gives more time for better soil improvement.
Cindy next to a long bed of pattypan squash. These summer squash are very cold sensitive and love warmth. This planting bed takes advantage of the concrete walls thermal mass, effectively moving this bed two or three zones south. It is unusual to see such vigorous and healthy growth in a colder climate.
This thermal mass technique has been used just outside Paris, France for over 300 years. Farmers grew extensive fruit tree and grape orchards in the cold climate of Paris.
Thick south-facing brick walls kept fruit trees and grape vines warm. Horticultural books showed why these orchards were so productive and grew such delicious fruits.
There are still remnants of these horticultural walls still standing outside of Paris today. Many of the current residents do not know why the walls are there, or what function they served!
When we looked in the bed, sure enough there was a large pattypan squash ready for harvest! This is about 2 – 3 weeks prior to the first expected frost.
The same concept is used for the tomatoes and basil, for different reasons.
This east facing retaining wall supports the pool and is not a traditional thermal wall. This growing spot is unique because the pool provides the moderating temperature. The pool has a lot of thermal mass, maintaining a steady temperature to the concrete.
In the summer, the wall absorbs warmth during the morning and gives shade during the hot afternoons. The water temperature is cooler than the air, so the wall’s effect is shading and cooling.
During cooler weather, the pool temperature is warmer than the air, warming the bed. The sun warms the bed during the first part of the day.
Up at the top of the herb garden section, the same technique is at work helping the snap peas have a good second season. They are climbing twine strings in front of the south-facing driveway retaining wall. The gardeners use this spot for an early planting of peas using the warmth as a jump-starter, transitioning to herbs later in the spring and back to peas in the fall.
Pretty clever to coax three plantings out of a 60 day growing season!
A different angle gives another look at the upper herb garden section. Notice the peas don’t extend past the warmth of the concrete retaining wall.
Some of the herbs are in pots, while others grow as annuals in the beds.
Notice the high fencing, which acts as walls for wind breaks and critter proofing. The garden is protected from chilling and drying winds and breezes, allowing more vigorous growth than if it were more exposed.
The hanging buckets are at the top right, seen in more detail at the top photo of the article. Individual herbs grow in each bucket, giving more fresh herb variety to the kitchen.
Now you see how simple techniques are used in creating a successful kitchen garden, no matter the size.
Take a close look at your garden to see if some of these approaches would work for you, or with a smaller container garden close to the house!
Cover crops – also called green manures – have improved soil for thousands of years. 3,000 years ago Chinese agriculture began planting horsebeans and sesame for soil improvement. Much later the Greeks and Romans sowed special crops to increase soil fertility.
The past 60 – 80 years has seen an incredible amount of knowledge emerge from small farmers experimenting with planting different cover crops and learning from what resulted. This knowledge was built on a foundation of several hundred years of European trial and error.
We now have access to detailed information about how to use cover crops for the maximum benefits in our gardens, pastures and fields.
Our Garden Cover Up Mix was developed from research into the specific benefits we wanted to bring to the home garden soil, as well as what species supported each other.
This photo essay is a look at what one month – 4 weeks – of growth provides in an average raised bed.
After sowing we began watering with our drip system, but the monsoon rains provided a good amount of water over the month. This helped the plant growth along, so your results may be a week or two behind these photos.
At one week, the mix has almost all sprouted and shown vigorous growth. The oats and rye are shooting up, looking like grass while the buckwheat spreads its leaves and the clover hugs the soil. The peas were just beginning to show up, as they took a few days longer to absorb moisture and begin germinating.
We planted the different parts of the mix separately to get an idea of how they grew by themselves and with other species in support.
The rye and oats both shot up rapidly, germinating within 3 – 4 days and showing good soil coverage.
The crimson clover was also up fast, creating a fluffy green blanket over the soil with its tiny green leaves. Even with only an inch of growth it was easy to feel the temperature differences between the tops of the leaves and the soil temperature – it felt like 15°F difference!
The buckwheat was a couple of days slower coming up than the oats or rye. Once the sprouts appeared they immediately opened their leaves and really started growing.
After three weeks the mix has almost completely covered the raised bed. The root system is about 3/4 of the top growth at this point, so the root density below the soil is almost as much as seen here. This is why cover crops are so beneficial to soil fertility.
A closer look shows how much shade the soil has and how thick the mix is growing. This out-competes most weeds above the soil while the roots choke out weeds below.
The young seedlings have just finished emitting auxins, a natural root hormone that inhibits other seeds from growing.
This mechanism gives the cover crops a head start over any other weeds for the next 2 – 3 weeks. When weed seeds can’t germinate, they will often rot as the soil fertility improves.
The growth accelerated going into the fourth week, as these photos show. The white PVC stake is about 14 inches tall. Last week the growth was about 3 – 4 inches, but this week it shot up above the top of the stake.
Besides putting on a lot of height, the mix also completely filled in the raised bed. Weeds have no space to grow and we could only find one or two after searching for them.
The soil is much cooler than the surface of the leaves. It is also moister, but that could be due to the amount of recent rains and not the cover crop. The buckwheat is starting to bloom and is attracting bees as seen in the top photo detail.
The buckwheat is the tallest of the mix at about 21 inches tall. The mix is extremely full and thick up to about 16 inches, completely choking out any weeds. The root system is still about 3/4 of the height of the plants, so there is an amazing amount of roots below ground! This shows why planting cover crops does so much to improve the physical structure of the soil.
As the roots die and decay they add organic matter to the soil, open up moisture and air pathways where the roots grew and increase the carbon content – all at the same time!
Pretty good for a few minutes spent planting the seeds and a months’ worth of growth!
Both the rye and oats look like really lush grass. They completely cover the soil and top out at just over 15 inches at one month. We couldn’t find any weeds in this test plot.
Looking closer at the density of the rye planting, it is easy to see why weeds don’t stand a chance. There is no room for anything other than the rye with this dense seeding rate, which is the point.
If a killing frost happened tomorrow there is enough growth to create an excellent mulch while the root system will feed the soil and its microbial populations.
Our first frost is still several weeks off so the cover crops will keep growing both above and below the soil level. The flowers need watching to prevent setting seed and creating another crop next season. We will clip or mow the flower heads as they develop if there isn’t a frost soon enough.
If the rest of the mix can develop before mowing or a killing frost, it gives more nutrition and benefits to the garden bed.
Cover crops will increase the bio-available nutrition in your soil for next season, even if you use a well-aged compost. Both approaches have benefits but if used together support each other and create a better, more fertile soil sooner than if only one is used.
You don’t need a lot of time to grow a good cover crop and seriously improve your garden soil – a month will do! Even if you only have 2 – 3 weeks you will be better off with a shorter planting than none at all.
Go plant some cover crops. Your garden will reward you handsomely next season!
Forest Highlands Kitchen Garden
Discover how a kitchen garden works in a cold, challenging climate. This 29 year old garden was put back into growing vegetables for the kitchen in 2015.
Cover Crops – Better Soil in a Month
Cover crops – also called green manures – have improved soil for thousands of years. We look at what one month of growth provides in an average raised bed.