Category Archives: Garden clean-up

Never Put a $10 Plant in a 10¢ Hole and Other Gardening Tips From Denver Master Gardeners

planting-1898946_1920Passionate gardeners love to talk about gardening, so with that in mind, we recently asked Denver Master Gardeners for their best gardening advice. Responses included tried-and-true practices, creative suggestions and good reminders for all of us as the gardening season kicks into full gear.

As the title of this post implies, we believe that great plants come from appropriate soil preparation. Amending with compost is often imperative as soil in our region tends to lack organic matter. But proceed with caution, as some plants, such as natives, prefer a leaner, less fertile soil. Too rich soil will cause these plants to underperform and often just flop over. It pays to do a little homework before planting, read seed package directions and have your soil tested.

One of our gardeners shared her recipe for amending soil: Add 1/2 a handful of both Alaskan fish pellets and triple super phosphate to half a bucket (such as a kitty litter pail) full of compost. Mix this into the planting hole for strong root development and beautiful blossoms.

A tip borrowed from the Rock Garden Society is to plant bare root. By gently shaking off most or all of the soil that the plant is purchased in, the plant will adjust to the garden soil without the soil interface (or boundary) that can occur between two soil types. Bare root planting promotes healthy root development.

mulch-1100555_1920Mulch, mulch, mulch is the mantra of many of our survey respondents as it keeps weeds out and moisture in. Add it like crazy each time you dig in the veggie, perennial and annual gardens and don’t forget container plants too. Small to medium-sized bark chips are popular, practical and pleasing to the eye. Natural mulch options are very effective, including not quite finished compost from the compost bin which will add carbon, feed living organisms, prevent water runoff and prevent compaction. Local arborists are often willing to drop off wood chips which would otherwise fill up the landfill. In the fall, mow over your leaves and spread them throughout the yard, they’ll breakdown by spring and add organic matter to your soil. Consider purchasing a chipper to grind up branches and other garden waste.

garden-hose-413684_1920Suggestions for responsible use of water include watering when the plant needs it instead of on a set schedule. Soaker hoses, often made from recycled material, are effective for watering plants at the soil line. Plants (even xeric ones)  need moisture to maintain healthy roots and overall strength, but often less than we think. For example, the Water Smart Garden at the Denver Botanic Gardens is watered about seven times during the season.

Weeding can feel like a no-win battle, but attacking weeds after a soaking rain makes the task easier. Pull weeds and unwanted volunteer shrub and tree seedlings when they are small, before they take hold in the ground or develop seed. Add stepping stones to the garden to avoid stomping on plants and compacting soil when working in the garden.

bindweed-1207738_1920A clever tip to eliminate stubborn weeds, such as the nasty bindweed shown here, is to take a large piece of heavy cardboard, make a cut from the edge to the center. Keep the cardboard as level as possible, slip the vine in the center and spray the vine with the herbicide of your choice or horticultural vinegar, which is sold in garden centers. The cardboard will protect surrounding plants from overspray. Aggressive weeds may require multiple treatments during the season.

One of our members recommends a tomato planting technique passed on through generations of farmers. She adds blackened banana peel to the soil and feeds them with skim milk upon planting and again one month after that. This less conventional practice yields her sweet, abundant fruit. While CSU can’t vouch for the scientific efficacy of this, the banana could be adding potassium and the addition of calcium may reduce the chances of blossom end rot.

plant-1585251_1920Growing tomatoes in containers is recommended for those with limited space. Select varieties which produce smaller fruit such as Patio, Cherry or Sungold. Use a large container (18+ inches in diameter), a sturdy support and a tray with casters. This allows plants to be moved from the path of hail or to optimal conditions. Container plants of all kinds benefit from weekly feeding of 1/2 strength fertilizer.

To keep pests at bay, try a thorough weekly spray of water during the growing season, including the walls of the house and fence. It’s a kinder way to shoo pests away.

If your vines need a sturdier trellis consider building one out of remesh, which can be found at hardware stores. It makes a durable, cost-effective support and can easily be cut with bolt cutters. It also can be attached to supports to create a dog run or create plant cages.

botanical-garden-413489_1920In the flower garden, invest in perennials for texture and dimension and add annuals for bold color. “Enjoy the randomness of some plants that choose their own spots to thrive” suggests one gardener. What a positive way to think of the seedlings that sprout up at this time of the year. Remember, too, that perennials may not come into their glory until the second growing season.

Gardening is a four season hobby. Winter watering of trees and shrubs will help keep them healthy and  veggie gardeners can get a jump on the season by using a cold frame or floating row cover to get an early start on lettuce, spinach and other cool season crops. Fall is a fantastic time to fertilize, aerate and over-seed the lawn. It is also an ideal season to divide perennials so that they settle in and are ready to take off in the spring.  Share your divisions with your neighbors, too, or trade for plants you’ve admired (envied?) in their yards. If you need more gardening space, solarizing or sheet composting is an excellent technique to ready a new garden bed and can be started throughout the year.

And lastly, a veteran gardener advises us to “Remember each little garden flower or planting arrangement is a moment in time. It will change. Don’t worry about it or take it too seriously.”

 

Written by Linda McDonnell with thanks to the many Denver Master Gardeners who shared their advice.

All photos courtesy of http://www.pixabay.com, a source of royalty free images.

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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hail Season is Here – Don’t Despair!

Gardening along the Front Range of Colorado is not for the faint of heart. We have to deal with poor soil, wild temperature swings, intense sun, a short growing season and hail. Somewhere in the Denver Metro area someone will experience the heartbreak of hail this season. It is hit or miss from year to year, but it is inevitable. The results can be devastating. In a few minutes,  a gardener’s hard work can lay in ruin.

Hail June 2015

Hail – June 2015

The first thing to remember when you experience hail damage is not to panic or lose hope. That is hard to do when everything in your garden has been shredded to confetti.  The initial inclination is to give up for the year and pull everything out. Don’t do it. Take a deep breath and stand back. Some plants may be done for the year, but others will come back even if they look terrible right now. Plants want to grow. They have an amazing ability to come back.

In 2015, our garden experienced two severe hail storms: one at the beginning of June and one the last week of June. We knew that most of our perennials would come back with time, but our vegetables were in a sorry state. Most were reduced to green sticks with a few tattered leaves hanging on for dear life. At that moment, it was hard not to throw in the towel for the season and head to the farmers market for produce. After much wailing and hand wringing, we went out in the garden and cleaned up the dead plant material. We took care to leave any foliage that looked like it might have a bit of life left.  Then we waited. Within a week or so, our tattered vegetable plants showed signs of renewed growth. Soon they were leafing out with abandon. We helped them along with light applications of liquid kelp fertilizer. By the end of July, we were harvesting vegetables from the same plants we thought were lost in June.  It was not our best harvest, but it was very good given the challenges we faced.

One small confession – we did buy a few new plants to hedge our bets. It was late in the season to buy vegetables at the garden center. The selection was not great.  The replacement plants got a late start and needed to get established. In the end, the replacements did not do as well as the original plants. Although the foliage on the original plants was shredded, those plants had been in the ground for over a month and had strong established root systems.  It’s not always what you see above ground that matters most.

If you have the misfortune this season to be hit by hail, remember:

 

  • Don’t panic.
  • Clean up the dead foliage.
  • Leave foliage that still has life.
  • Do light applications of fertilizer.
  • Be patient.
  • Click here for more tips.

By Mark Zammuto,  Denver County Master Gardener

Fall in the Perennial Garden: The Case for Less Clean Up

Mid Summer BorderI don’t know about you, but in my perennial garden, fall cleanup can be hit or miss. Whether a function of limited time, gardener burnout or an early cold spell, some years I just let it all freeze dry in place till the spring. What I’ve found is there are some really good reasons to do less fall clean up and I’m not as lazy as I once thought.

Here’s the case for leaving most perennial flower garden cleanup for the spring:

  • Dried foliage will help protect the crown of perennials from the freeze/thaw cycle; this is especially good for marginally hardy perennials. If  you decide to prune, leave about 3-4 inches from the ground to avoid damaging the crown.
  • Dead stems “mark” the plant and lessen the chance of accidentally digging it up or stomping on it in the spring. This can be really helpful for plants that wake up a bit later each spring (Threadleaf Coreopsis does this in my garden).
  • Plants may drop seeds and give you additional seedlings to love or give to friends next year. Such was the case with the Black Eyed Susan’s/Goldsturm Rudbeckia in the photo above.
  •  Seed heads provide tasty food for birds.
  • Enjoy the natural beauty of the winter landscape such as the ornamental grasses moving in the wind and the various colors and textures of foliage, which can be especially lovely when covered with a dusting of snow.

Bright pink Salvia Greggii /Wild Thing Sage. This semi-woody plant should be pruned in the spring. Photo courtesy of PlantSelect.org.

  • Some plants highly prefer spring pruning, such as grasses and plants with semi-woody stems such as Munstead Lavender and  Wild Thing Sage or Salvia Greggii. A spring haircut when new growth emerges often yields a plant with better form and growth. (Not to mention increased chance of winter survival).
  • Early season flowering shrubs such as lilac have already put on the growth that produce next year’s flowers. If you cut now, you will not have blooms next spring. These plants should be pruned soon
    Lilacs which were side pruned too late in the season. Photo from CSU CO Master Gardener Garden Notes #616
    Lilacs which were side pruned too late in the season. Photo from CSU CO Master Gardener Garden Notes #616

    after they are done blooming. A good general rule for lilacs is prune no later than July 4th.

Now, having said all that…here are beneficial fall care tips:

  • Cut back overly assertive perennials whose seedlings take over the garden and become a nuisance. Denver Gold Columbine and Walker’s Low Catmint are prime examples in my garden.
  • Remove leaves of plants that had powdery mildew or other foliage diseases. This will cut down the chance of the problem festering in the soil and re-emerging next spring.
  • Trim long rose canes  which can get damaged by the wind, otherwise don’t prune roses.
  •  Apply light mulch after plants have gone dormant, usually after a few hard freezes. Avoid packing mulch down too tightly so that beneficial moisture can reach the plant and the mulch does not spawn mildew or mold.
  •  Water during dry spells.  When there is little fall/winter precipitation  give the landscape a drink once a month, when temps are over 40 degrees and as early in the day as possible.

Personal preferences vary, so do what’s right for you. Just don’t beat yourself if you kick up your feet and leave most of the chores till the spring!

References for this post:

Winterizing Perennials, Plant Talk 1020

Maintaining Perennials, Plant Talk 1019

Winterizing Perennials During Drought, Plant Talk 1064

Written by Linda McDonnell, Denver County Master Gardener

Spring Garden Clean-up

Spring Garden Clean-up

If you are like me, the autumn clean-up in the garden often rolls over into spring.  With warmer days bringing thoughts of planting, now is the time to finish up (or even begin) those garden clean-up chores.  Start with cleaning your tools and sharpening blades if needed.

One preliminary note – the severe sudden cold that the Front Range experienced in November of 2014 will lead to damage of plants which will not become apparent until this spring in 2015.  Temperatures dropped from the high 60’s to minus 14 degrees over 4 days causing damage to needles and bud on trees, possibly killing other garden ornamentals, and freezing roses down to the ground.  See the following Landscape Health Bulletin from the Extension Service for details on trees and how they may be affected: https://plantclinic.agsci.colostate.edu/files/2014/06/Polar-vortex-bulletin-Feb-2015.pdf .

Since some deciduous trees and bushes are bare of leaves and some are still dormant, assess them now for pruning needs.  Trim out branches that cross one another and rub together, or that were broken or damaged by wind or snow loads.  It is better to wait on pruning such trees as birch, maple, walnut, and elms.  They will often “bleed sap” when pruned in the spring and respond better to pruning in the summer after leaves grow and turn a full summer green.

Do not prune spring blooming trees and shrubs at this time.  The flower buds were set in the summer or fall of the previous year and pruning will remove this year’s blossoms.

Cut back dead leaves on perennials and leggy stems on ornamental grasses.  Trim woody perennials which only bloom on new wood, such as lavender or buddleia, after hard frost danger has passed. Remove and compost debris from dead annual flowers, the spent dry leaves from irises, and any remaining ground-fall leaves not being utilized for mulch.

Spring garden clean-up time is great for an early start on weeding.  When the ground is soft and damp and the weeds are small, it is much easier to remove them than to wait until they are ready to swallow your ornamentals.  Weed a little every time you tour your beds, and the job will not become overwhelming (we do hope.)

When perennials start to emerge, it is an ideal time to divide and transplant them.  As you do so, assess your beds for the need for additional mulch.  Also, now is a good time to check out any irrigation systems, particularly drip hoses and soaker hoses, for any leaks and holes needing repair.  Add mulch where needed (or wait until you add any new plants to the beds) and edge beds anew.

What about soil amendments?  Now is a good time for a soil test if you have not submitted one recently, particularly for ornamental and vegetable gardens.  Test kits are available from your local extension office and some nurseries and greenhouses.  A CSU fact sheet on soil tests is available at the following link: http://www.ext.colostate.edu/mg/gardennotes/221.html

Although it is tempting to trim all the dead wood on roses, it is best to wait until the end of April or early May.  (The Denver Rose Society suggests waiting until the forsythia are blooming in your neighborhood.)

You should also get your containers ready for the gardening season.  Clean out any dead plants, add additional container soil, if necessary, and start designing for spring.  Consider some cool weather crops like lettuce or spinach for early containers.

Do you have a compost pile?  Now is a good time to turn it and get it ready for use.  If you have mature compost, you may wish to apply some to beds before mulching and planting.  Wait for the soil to warm before planting tender annuals, generally around Mother’s Day in the Denver area.  You can plant early cool-weather spring vegetables as soil conditions allow, usually as early as the beginning of April.

If you have early blooming bulbs such as crocus and tulips, do not cut the foliage from the spent blooms. The foliage is busy making food for next year’s bulbs and flowers.

These tips will get you started on a new canvas for your artful and fruitful spring and summer garden.

By Mary Beth Cooper, Denver County Master Gardener