Category Archives: Organic gardening

10 Reasons for Becoming a Denver Master Gardener

If you like to plant and grow things, you may be a Master Gardener in the making. A desire to help your community is another plus. In case you need more convincing, consider these 10 benefits of joining us and then take the next step to become a Colorado Master Gardener.

Number 10: You’ll be a better gardener. Becoming a Denver Master Gardener doesn’t mean you’ll be a perfect gardener, but at least you’ll know why the daisies died, what’s wrong with your tomato plant, why the lawn has brown spots, and what the heck is eating those roses. The CSU Master Gardener program is like getting a mini-degree in horticulture.

Number 9: You’ll help with important research. Master Gardeners are often called on to help with CSU Extension research projects. One recent project included collecting tree data as part of the Rollinger Tree Collection Survey project, a collaboration with the Denver Botanic Gardens and other partners to understand the past, present and future of Denver’s urban forest.

Master Gardeners like to meet, mingle and break crab legs together.

Number 8: You’ll meet and mingle with like-minded folks. Gardeners like to talk—and listen. Whether you’re a social butterfly or just like to belong to a tribe with similar interests, there are plenty of opportunities to enjoy each other’s company.

Number 7: You can share your knowledge. People have questions and now you’ll have the research-backed information to provide answers in person at farmer’s markets and special events or by answering email questions from home. There’s a lot of gardening misinformation out there, but you can help dispel the myths (except when it comes to marijuana).

Number 6: You can volunteer in meaningful ways. Community outreach is an important part of being a Denver Master Gardener and others appreciate your contribution. The vegetables grown in the Harvard Gulch Demonstration Garden are donated to help feed the hungry; The Haven at Fort Logan offers another chance to serve others with your gardening skills.

Master Gardeners plan and plant the CSU Extension exhibit at the Colorado Garden and Home Show.

Number 5: You’ll get to work behind the scenes at the Colorado Garden and Home Show. A favorite volunteer project is being part of the annual show whether helping to build the CSU Master Gardener display or answering attendee’s questions. Free entry to the show is an added bonus.

Number 4: You can stretch your leadership skills. Being a Master Gardener lets you take the lead on a special project in a safe and supportive environment. Creativity, innovation and new ideas keep the program interesting.

Number 3: You’ll receive a well-recognized credential. Anyone who’s been paying attention has heard of CSU Extension’s Master Gardener program. The title is a well-known and well respected credential in the gardening world and in every state across the country.

Number 2: You’ll be supporting an important educational program. Becoming a Master Gardener isn’t free, but the nominal annual fee ensures the Denver Master Gardener program can continue its mission.

Being a volunteer at the City Park Greenhouse refreshes gardening skills for the new season.

And the Number 1 reason for becoming a Denver Master Gardener: Volunteering at the City Park Greenhouse.  It’s one of the most revitalizing volunteer gigs, and it happens at a time of year when gardeners need it the most.

Those are my top 10 reasons. What are your top reasons for becoming a Denver Master Gardener?

By Jodi Torpey
A Denver Master Gardener since 2005

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Fall: The Science of Color and Options for Clean-up

In Colorado and many other states in the US, we enjoy fabulous fall color in our gardens, parks and wilder landscapes.  We notice it most on trees, but many shrubs and other plants change color in the fall too.  Have you ever wondered where all that color comes from?  Why do the leaves drop off the trees?  And what use are all those huge drifts of dead leaves to us?

Color

Most plants have green leaves.  This is because chlorophyll in the leaves absorbs the red and blue parts of the light spectrum but reflects green light-waves so we see “green”.  Chlorophyll is used in photosynthesis.  This is the chemical process by which plants convert light, carbon dioxide and water into oxygen and carbohydrates – i.e. food for the plant. Chlorophyll is an unstable compound and the plant continuously replenishes it throughout summer when good sunlight and high temperatures prevail.

When temperatures cool and nights lengthen, chlorophyll production stops and so does photosynthesis (the plant’s food production system). As the green-reflecting chlorophyll disappears, other colors “appear.”  In fact, these colors were always present in the leaves but now they are no longer masked by the green light-waves reflecting from the chlorophyll.

Carotenoids absorb blue-green and blue light and reflect yellow light waves.  This is perceived by the human eye as yellow or greenish-yellow.  This is why the fall color of birches and aspens is yellow.

Anthocyanins absorb blue-green, blue and green light and reflect red light-waves.  This is perceived by the human eye as red through to purple.  This is why the fall color of red oaks, sumacs and some maples is red.

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Acer tartaricum ‘Hot Wings’ still green

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Acer tartaricum ‘Hot Wings’ turning red

 

 

 

 

 

 

 

The depth and shades of fall color depend not only on the presence (or absence) of these pigments, but also the temperature and sunlight available.  Low temperatures and bright sunlight destroy chlorophyll.  So, falls with dry, sunny days and dry, cool nights tend to produce the best fall color.

In severely dry falls, the lack of moisture available to the plant may mean that leaves simply die without producing their usual fall colors of yellow, red or purple.  The leaves lose so much moisture that the normal chemical processes cannot continue and the leaves dry, turn brown and drop early.

The ‘Fall’

Once the spectacular show of fall color is over, deciduous (i.e. leaf-losing) trees and shrubs drop their leaves.  Cooling temperatures and lengthening nights trigger plants into sealing off the point on their stems where leaves are attached so that no more exchanges of moisture and nutrients between the leaves and the rest of the plants are possible.  This is called the “abscission layer”.  When this layer is complete, the leaves drop (or “fall”).

What use are those dead leaves?

Think about how nature deals with this “problem”.  Leaves fall from trees to the ground of the woodland, forest, mountainside, meadow – wherever they are situated.  Rain, frost, snow, the trampling of animal feet all help to break the leaves down into smaller and smaller pieces.  A huge drift of fallen leaves decreases significantly in size as air spaces between the leaves diminish.  An army of creatures from the soil surface, and from beneath it, break down the leaves further through eating and excreting them (think: earthworms, beetles) or chemically decomposing them (think: fungi, bacteria).   In this way, the dead leaves are decomposed into the tiny elements that create soil.  It’s a mixture of humus and minerals.  The humus is the last vestiges of the leaves that are hard to break down like cellulose and the minerals are the chemical components of the leaf tissue, e.g. nitrogen and carbon.

The humus and minerals help to form new soil structure in which new plants can seed, germinate, develop and continue the cycle.  The new fertile or replenished soil provides the moisture and nutrients that the now-leafless trees will need to survive winter and re-start photosynthesis and growth in spring.

How to deal with those huge piles of leaves

We’ve seen above that the dead leaves have an important part to play in the garden’s eco-system.  So, what can you do?

  • Just let the leaves remain where they drop on garden beds. They provide great mulch to maintain soil temperatures and protect plant roots and will rot down over winter, improving your soil as they go.
  • Leave a thin layer of leaves on lawns. Rake or blow them off (if you must) but a thin layer of leaves (especially if you run over them once or twice with the lawnmower) will break down quickly and help re-vitalize your lawn.
  • Rake or blow leaves off walkways, drives and sidewalks on to adjacent garden beds, so that these hard landscape areas are visible and don’t become slippery. Do not sweep or blow leaves into the street, as they can cause serious blockages in street drainage systems.
  • For a neater look, you can blow the front edge of borders clear, letting the leaves accumulate at the backs of borders and behind and below larger plants.
  • Put layers of leaves in your compost bin (even better if you can run the lawnmower over them first) between your layers of green garden/kitchen waste.
  • Save the leaves in plastic trash sacks (stored in an unobtrusive part of the yard) and let them rot down over winter, to be returned to the garden when they have decomposed. This leaf mold (the lovely dark brown material you get from decomposed leaves) is like “gold-dust” to the soil.
  • Save the leaves in an open cage made of upright posts and chicken wire to decompose – more “gold-dust”. If you have room, let your neighbors drop their leaves in the cage too.
  • BUT if leaves come from a diseased plant e.g. one with powdery mildew, black spot (roses), apple scab, anthracnose, they should be collected up and disposed of as garbage to help prevent re-infection in the next year.
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Leaf cage made from old timber and chicken wire

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Fallen leaves make great mulch (and are warm and cosy for the dog!)

If none of these options work for you, you can dispose of the leaves in degradable paper sacks which are usually available from your local hardware store at this time of year.  The sacks can be collected with your normal weekly trash service.  Some towns and cities will have leaf drop-off points where you can take the bags for the city to collect.  The city will then use the leaves to make leaf mold for local parks or otherwise dispose of them.  If you can’t do these things yourself, look for a local lawn service company that can, or hire a local teenager to help.

But, whatever you do, remember that the leaves really belong on the ground.  That’s nature’s way, after all.

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Acer saccharinum (silver maple) turned yellow

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Quercus rubra (young red oak) turned red

Anne Hughes/Denver County Master Gardener

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sheet composting or … cooking up an experiment in the garden

I’ve always known that the soil in the garden was the key to planting success.  So, when we started our new Denver garden in 2014 we turned in most of the turf and dug, weeded and added leaf mold to the topsoil.  (We had kept all the fall leaves for this purpose.)  Then all the bare soil was covered with a 3-4 inch mulch of wood chips.  Key trees were planted in spring 2014 with more trees, shrubs , ornamental grasses and herbaceous perennials following in 2015.  We watered diligently till the winter and snow came.  We thought we’d made a good start.

In spring 2016 I was delighted to see our young trees and shrubs budding out .  Most of the herbaceous perennials had survived, but they didn’t increase in size during the summer. They hardly bloomed.  They didn’t die.  They just sat there.  Watering seemed to make no difference.

I figured that the larger plants (trees and shrubs) were able to get their roots down into the clay where there was more moisture and more nutrients.  But the perennials were struggling with their smaller root balls being mostly in the 8-10 inches of sandy loam topsoil.  Here water drained away quickly and despite the wood chip mulch, the unrelenting sun and high temperatures baked the soil to an iron hard cap over dull powdery stuff below (if you could get the spade in that far!).

I had a soil test done by the soil laboratory at CSU which told me that our topsoil was low in nitrogen and organic matter.  Ah-ha!  That is why the plants weren’t thriving.  The lack of nitrogen was slowing the development of stems and leaves.  The lack of organic matter meant the soil wasn’t holding sufficient water for the plants’ roots to take up.

OK, I thought, we have to do more to improve the soil. I’ve never liked the idea of just throwing chemical fertilizers at the garden.  It’s expensive, wasteful and potentially dangerous to the wider environment.  Double-digging and adding store-bought amendments (of uncertain quality) is back-breaking and expensive. What to do?

Soil is not tilled in the natural world.  Fertility is built up by the decomposition of leaves, twigs and other plant waste on the surface.  Soil texture and nutrient levels are also improved by the actions and decomposition of organisms living in the soil and plant roots.  I’d just been reading about permaculture gardening techniques and the soil improvement technique of “sheet composting” or “lasagna gardening” seemed to be what we needed.

This is a way of building up organic matter and nitrogen in the soil without digging.  You gather different sorts of compostable material (green garden waste, compost, grass clippings, straw, dried leaves, well-rotted manure are just some you can use) and pile them up on the soil in layers.  Hence “sheet” composting or “lasagna” gardening. Essentially, you are making compost directly on top of the soil rather than in a compost bin elsewhere and then transferring it later to the garden.

Many books suggest that you also lay newspapers or plain cardboard down first to smother any existing weeds in the ground.  This is usually where you are trying to improve a weedy, uncultivated area.  But such two dimensional materials can be a barrier to the passage of water, nutrients and the essential soil creatures (see below) that you need to make the process work.

Cardboard layer to start

Cardboard layer to start. Existing wood chips raked on to path first.

Cardboard often incorporates waxes which inhibit the movement of moisture and make it hard to break down.  Shredded newspaper in half inch layers may be a better alternative, but not perfect.  I did use cardboard, but in hindsight probably didn’t need it as the soil was not weedy at all.

Every layer has to be thoroughly soaked with water including the existing soil.  The fungi, bacteria, insects, beetles, earthworms etc. that will break down your materials need water to do their work.

My “recipe” comprised from bottom (soil level) to top:

  • cardboard (on reflection, probably not needed)
  • garden compost (precious stuff from my own bins)
  • grass clippings from a neighbor’s “pile” and half a bag of left-over peat moss
  • partially decomposed garden waste from another neighbor’s “pile”
  • wood shavings and straw from another neighbor’s old chicken shed
  • grass clippings again
  • leaves collected in our leaf cage from the previous fall
  • more partially decomposed garden waste
  • wood chips to hold it all in place and for aesthetic appeal

The layers amounted up to about 12 inches of material.  Each layer was watered in.  Grass clippings were laid in approximately 1 inch layers while the other materials were laid in 3-4 inch layers.  You need much more brown material by volume than green.

Straw and partially decomposed garden waste

Straw and partially decomposed garden waste

Just like making compost conventionally it is important to have a mix of “green” and “brown” materials or, in chemical terms, sources of nitrogen and carbon.  Too much green (e.g. grass clippings) and you have too much nitrogen.  Too much nitrogen will encourage leafy top growth in your plants at the expense of root and fruit/flower development leading to straggly unhealthy plants.  Too much brown and the materials won’t break down sufficiently.

But the green/brown or nitrogen/carbon balance isn’t just about your plants.  All the living creatures in your soil need the right balance too.  They have to live, multiply, work the soil, die and decompose in order to release the precious nutrients to your plants.  The soil creatures need to feed before your plants can.

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Last year’s leaves go on

It’s important that the materials you bring in don’t also bring in weed seeds resulting in a huge weeding problem for the next year.  But the theory is that any weed seeds that do come in will rot in the damp condition of the layers. And if they don’t rot first, they won’t germinate anyway due to lack of light.

The biggest part of this job is sourcing and gathering all the materials.  There were many trips to neighbors’ gardens with rakes and shovels.  Then the trips home again with a car full of other people’s “waste” in old plastic bags. It is hard work.

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The finished thing

So, now we have some 60 feet of garden borders resting for the winter under their layers of composting (we hope!) materials.  We also have many other areas where fewer layers were used (mainly straw with grass clippings or partially decomposed garden waste) to about 3-4 inches to perk up the soil around and between trees and shrubs.

Many questions remain:

  • Will the cardboard decompose?
  • Is the “green” and “brown” balance right?
  • Will the raccoons and skunks churn it all up?
  • Will there be a crop of new weeds from the imported materials?
  • Will the cold Colorado winter simply stop any decomposition from taking place?
  • Will there just be a smelly slimy heap to remove next spring?
  • OR, will we have achieved that elixir of gardening – fertile, well-drained, moisture-retentive soil???

Well, the answers to all these questions will be given next year when I report back in another post.

In the meantime, what do you think? Have you tried this? Did it work well? Please share your comments below.

Anne Hughes  – Denver County Apprentice Master Gardener

CSU Webinar Helps Solve Garden Mystery

Deformed tomato leavesEvery summer is different in the garden, but this year I found something I hadn’t seen before with two container tomato plants. The new leaves on these  plants was stunted and twisted into odd shapes.

Like many gardeners, I’ve seen plenty of tomato problems in my garden over the years. Early blight, late blight, blossom end rot and insect damage have cropped up from time to time, but these twisted leaves had me stumped.

I looked for images of similar problems online and checked my Tomato MD app, but I couldn’t find anything else that looked like that deformed growth.

In a great gardening coincidence while I was finishing my Colorado Master Gardener continuing education requirements, I clicked on a Small Acreage Management (SAM) webinar, and the mystery was solved.

These SAM webinars are posted on YouTube, so any gardener can watch them for free. The one that helped me diagnose my tomato plant problem is called “Herbicide Carryover and Fall Garden Care” led by Darrin Parmenter of CSU Extension in La Plata County, dated Sept. 4, 2013.

Herbicide carryover can happen when gardeners use herbicide-treated hay, straw or grass clippings as mulch or compost in their gardens. Herbicide carryover can also occur if gardeners apply manure from livestock that ate treated pasture or crops. Tomatoes and members of the tomato family are especially susceptible to herbicide carryover.

I’ve used well-aged horse manure in my garden for years and there’s never been a problem until this season. It turns out that herbicide carryover from horse manure is the top pathway because herbicides can pass through horses so quickly.

As soon as I understood the problem, I started a remediation program to improve soil microbial activity in the two containers with the affected tomato plants. I’ve cultivated the soil to increase oxygen, added a different kind of organic matter to increase beneficial soil organisms and used a home-made organic mulch. I’m also keeping the soil evenly moist and using a liquid fertilizer once a week.

According to Darrin in the webinar, the tomato plants may recover if there’s enough vegetative growth. I’m certainly going to be more thoughtful with how I amend my garden soil in the future.

By Jodi Torpey
A Colorado Master Gardener

Seed School

You may be familiar with the Seed Savers Exchange in Iowa. As a member you can buy or exchange seeds with other members.  They encourage heirloom seed saving.  You can grow the same variety of Hollyhock or Sunflower that your grandmother grew because people have saved the seeds and passed them along for other gardeners to grow.  seeds

A relatively new organization is the Rocky Mountain Seed Alliance.   The founders of the Rocky Mountain Seed Alliance spoke at the Denver Botanic Gardens in September 2015 – “Seed: the Future of Food”.   Seeds saved from successful plants are uniquely adapted for the local environment which makes local or regional seed groups important.

Both of these organizations offer “Seed Schools” where they teach best practices in seed harvesting and preservation.   The Rocky Mountain Seed Alliance offers webinars on seeds and has a seed school in Aurora, CO in August 2016 

If you want to see some interesting videos about International Seed Banks see my earlier post on this site.

Seed Research in Fort Collins, CO

Staff at the National Seed Storage Laboratory in Fort Collins, Colorado, preserve more than 1 million samples of plant germplasm. Here, technician Jim Bruce retrives a seed sample from the -18 ºC storage vault for testing. Photo by Scott Bauer.

Staff at the National Seed Storage Laboratory in Fort Collins, Colorado, preserve more than 1 million samples of plant germplasm. Here, technician Jim Bruce retrieves a seed sample from the -18 ºC storage vault for testing.
Photo by Scott Bauer.

The Plant Germplasm Preservation Research Unit, is part of the Agricultural Research Service (ARS).   The  National Center for Genetic Resources Preservation (NCGRP) is in Fort Collins, CO.  They collect, store, test and research  both plant and animal genetic resources.

The National Seed Storage Laboratory is part of the National Center for Genetic Resources Preservation.

The seed storage lab “opened in 1958 and was expanded in 1992. • Seeds are packaged in moisture proof foil bags for cold vault storage (-18°C; 0°F). • Cryogenically (liquid nitrogen, -196°C; -320°F) stored seeds are sealed in polyole n tubes.”

“The testing and storage protocols developed at NCGRP are shared with other researchers and genebanks and our expertise is used worldwide.”  “Seeds are evaluated for viability (tested for germination or dormancy) before and during storage”.

They recently sent seed to the Svalbard Global Seed Vault in Norway which “included a wild Russian strawberry that an expeditionary team braved bears and volcanoes to collect.”

Field collection of seeds can be a very adventurous scientific career.  Collecting seed from your own garden is usually less exciting — but equally important.  I hope you saved some from last year for use in your garden this year.  Please subscribe to this blog for continuing stories about seeds.

Balcony Gardening – Grow A Salad Bowl

Now is a good time to plant baby lettuce, spinach and micro-greens for early Fall harvest.  You do not need a deep container to grow salad greens and you can grow the greens from seed.  Covering the potted seeds with loose plastic wrap holds the moisture and heat and encourages sprouting.

Growing Container Salad Greens:  “You will be able to harvest your first crop in just a few short weeks, using the small tender leaves that are often not available to buy. These micro-greens are the mix of choice for gourmet salads. Leafy greens also make a flavorful addition to sandwiches or wraps.”

Salad greens

Radishes also mature quickly.  Use radish greens instead of basil in your pesto recipe.Radishes

As a container gardener you can quickly move your salad bowl inside if we get a sudden Colorado frost.  In a sunny window you can keep growing salad all winter.

If you need an incentive, a CSU Extension publication lists the nutrients in different salad greens and has notes about taste.  It has great photos — I can now identify Mizuna.  Enjoy!