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Written by Dr. Tony Koski, Extension Turf Specialist
Department of Horticulture and Landscape Architecture
http://csuturf.colostate.edu       http://csuhort.blogspot.com

Lawns that are covered by flood waters, even temporarily, may be subject to various types of damage. In general, most turf species will tolerate a few days of flooding without any negative effects. However, turf that remains flooded for more than a few days (especially when it is hot) can rapidly decline due to lack of oxygen and light. Substantial turf loss can be expected after 4 days of continued submersion. Other factors associated with flooding of turf include: soil coverage, water contaminated with petroleum or pesticides, high water temperature and algae scum. The most significant long-term effect of flooding is the deposit of sediment (“muck”), primarily silt and clay, over turf surfaces. This can lead to serious soil layering problems and even death of the existing grass.

Short-Term Care of Flooded Turf
Once flood waters have receded, pick up any debris, such as wood, glass, stones, nails and other metal objects deposited on lawn areas. This debris could pose a safety hazard to mower operators and damage power mowers or other equipment later used to maintain the lawn, as well as to people and pets who may use the lawn for recreation. Remove leaves or any other material that may smother grass.

Soil (“muck”) deposited on a lawn can sometimes be removed before drying by a combination of scooping/shoveling and washing with a jet of water using a hose-end sprayer.  However, removal of soil may be impractical or impossible due to the size of the lawn area, the depth of the soil, the weight of the wet soil, and ability to move it to another location.

Soil deposits on golf greens and other sand-based turf systems (soccer, football or baseball fields) should be removed as quickly and thoroughly as possible to reduce the potential for silt and clay to move into the sand root zone, clogging the pores and reducing infiltration and permeability. The use of shovels, sweepers and water to move/remove soil deposits will reduce the potential for damage. However, these affected turf systems will likely require aggressive core cultivation and topdressing to restore and maintain acceptable infiltration and aeration.

After the Turf has Dried
It is often not possible or practical to remove deposited soil from flooded turf while it is still wet. The drying process may take two or three weeks, perhaps longer, depending on weather, soil, and drainage characteristics of the underlying soil and turf. Remediation at this point is largely dependent upon the depth of deposited soil.

Lawn repair with less than 1-2 inches of soil
Lawns submerged less than 4 days and covered with an inch or less of soil have a good chance to recover.  Assessment of potential lawn damage and recovery may not be possible until those areas have dried. Checking for new shoots emerging from the soil or the emergence of new shoots from surviving plants is a good way to make an early assessment of damage. Usually, once regrowth has begun, it will continue, although it may take several weeks before the lawn has completely filled in.

Core cultivation/aerification is one of the most important and beneficial operations conducted where soil deposits are less than an inch. When the lawn has begun to grow (green leaves begin to appear), go over the lawn 3-4 times with a core type aerifier. This will help improve overall soil structure, improve soil oxygen levels, help break up soil layering problems caused by the deposited soil and encourage recovery during the fall. The lawn should also be fertilized (using any lawn fertilizer, following label instructions for applying the correct rate) at this time (September-October).

Overseeding can also be done at the time of aerification. The aerification holes provide perfect conditions for the germination of grass seed. Lawn areas that are thin (or the entire lawn can be overseeded at this time) can be overseeded with Kentucky bluegrass or a Kentucky bluegrass/perennial ryegrass mix (tall fescue lawns should be overseeded with tall fescue seed), using a seeding rate of 5-6 pounds of seed per 1000 square feet. Rake the lawn lightly after seeding to work seed into the aeration holes. Irrigate the lawn to maintain moist, but NOT saturated, soil conditions.

Lawn repair with greater than 2 inches of soil
Lawns covered with more than 2 inches of soil may be heavily damaged, with only a slight chance of recovery. Degree of recovery will vary with grass species and depth of soil. The greater the depth of soil, the slower the recovery and the less likely the lawn will recover. If the lawn area is completely buried with many (3 or more) inches of soil, then the best strategy may be to accept that the majority of the lawn has already been severely damaged or killed and it will be necessary to reestablish a “new” lawn.

Reestablishment of a “new” lawn over a flood-damaged lawn
To reduce the future potential for soil layering to cause drainage and rooting problems for the new lawn, there are two ways of dealing with the deposited soil. One is to remove as much of the soil as possible, down to the original lawn surface. Understanding that this may be difficult or impractical, the deposited soil may be left on the lawn and rototilled into the lawn as deeply and thoroughly as possible. This, in essence, will create a “new” lawn root zone that is a mix of the deposited soil and the underlying lawn and its soil. The goal is to eliminate, as much as possible, the formation of layers in the “new” lawn root zone by thoroughly mixing the original lawn’s soil, the layer of the original, dead lawn, and the flood-deposited soil.

After leveling and firming the “new” lawn soil, it can be sodded or seeded as any new lawn would be established. Cool-season grasses can be seeded anytime between Aug. 20 and Sept. 30 (buffalograss should be seeded in April/May). Sod can also be used to provide an instant lawn. Do not sod over existing dead or buried vegetation. The old dead layer of lawn grass must be thoroughly tilled into the soil before laying new sod.

Written 18 September 2013

If you’re cleaning up your vegetable garden after the flood waters recede, consider the safety of eating produce from the garden.  If rain, and only rain, fell on the garden everything is fine, but if it was touched by or near flood water, your produce is risky-to-dangerous to consume.

Flood waters can contain sewage, pollutants such as oil, gasoline, solvents, etc., bacteria and parasites such as Giardia, Cryptosporidium, E. coli, Shigella, Hepatitis A, and a host of other unsavory contaminants.  Young children, seniors, pregnant women, and people with compromised immune systems are at highest risk for serious effects from consuming contaminated food and should not eat any produce that was in or near flood water.

In every case where the edible portion of the plant came into contact with flood water – submerged or splashed – there is risk, regardless of whether it is above or below ground.  In many cases, there is no effective way for washing the contaminants off of the produce.

To help you sort through what to do for crops that were near to flood waters, here are quick tips:

All crops eaten raw should be discarded, such as lettuce, mustards, spinach, cabbage, collards, Swiss chard, arugula, or micro greens.  Soft fruits like strawberries, raspberries, or blackberries as well as leafy vegetables such as spinach, chard, beet tops, or kale may be impossible to clean well and must be cooked before eating; avoid eating them raw.  Because rain or sprinklers can splash contaminated soil back onto these plants and contaminants can become embedded in the leaves, stems, petioles, etc., the area is not safe for growing for 90 days, minimum.

Root crops, including carrots, radishes,  parsnips, beets, or potatoes should be washed and rinsed in clean, potable (safe for drinking) water, sanitized in a dilute bleach solution, and then rinsed in potable water.  They should also be peeled and cooked before consuming.

Make your sanitizing solution by mixing a scant tablespoon of food grade bleach, without fragrances or thickeners, to one gallon of potable water.  Wash the produce with clean, potable water, using a vegetable brush to clean in crevices.  Rinse, then dip into the sanitizing solution for two minutes, then rinse in clean water.

Peas, beans, tomatoes, peppers, eggplant, summer squash and other soft skinned crops that are present during the flood should be discarded.  Winter squash, winter melons, and pumpkins, with their thick rinds, can be washed and rinsed in potable water, then sanitized in the dilute bleach solution described for root crops, and rinsed.

Questions on stage of plant growth versus potential for contamination can be summed up in this very good Purdue University response from Liz Maynard, Regional Extension Specialist, Commercial Vegetable and Floriculture Crops: “Risks can be described as follows:

•Edible portion of crop present: Very High Risk.  Fresh produce is considered adulterated.

•Plant emerged, edible portion not present: High Risk.  The potential presence of microorganisms in the plant as well as in the soil could result in indirect contamination of the crop post flooding (splashing onto plant, etc.).

•Planted but not emerged: Still High Risk for reasons given above from post flooding contamination in soil.

•Pre-planting: Moderate Risk.

Soil contamination may be as dangerous as that of uncomposted manure. Tilling in the soil and a minimum of 90 days between the recession of waters and harvest are needed to reduce this risk from pathogens, but recovering soil from chemical pollutants may take longer.

To protect crops and areas not directly touched by flood water, wash your hands before and after you’re in the garden, leave your garden shoes just outside your door, and change out of clothing you wore to work the vegetable patch.

Weeds?

Weeds? (Photo credit: Cyberslayer)

Strolling the garden in the wee morning hours is a ritual for my spouse and me, one that lets us see how each plant is faring as the summer progresses. We check stems and leaves for pests, tuck in errant vines, and admire blossoms.  But when we get to the old perennial bed on the side of the driveway, excited chatter turns from new sprouts and swelling flower buds to dismemberment and destruction.

 The bed, which should be a showcase of the yard, is overrun with bindweed and thistle.  Passersby approach the riot of flowers with eagerness, only to recoil in horror at the sight of perennials being choked by weeds.  Days spent trying to get them under control only serve to make them determined to overrun the garden.

 A tug of war has ensued; during the day the weeds pop up under cover of foliage or coil around taller perennials.  Each morning, I halt in my tracks to pull them out.  Balancing a full cup of coffee while bending over to yank out weeds has become a special skill, one that my spouse admires as nary a drop of the tan liquid is lost.

 While I’m impressed with the growth of most plants at this time, the weeds are coming up faster than I can keep up.  Pulling them is a season long job.  In pursuit of weed control many gardeners abandon some rudimentary connections to the world around them, such as notifying your boss that you’ll be late – again – to the office.

 Some of the tougher weed characters in the garden may change from year to year.  This year there is Western Salsify (Tragopogon dubius), a grassy-looking biennial that is sprouting in many gardens.  Western Salsify’s grass-like leaves arise from a central stalk which, when damaged, oozes a milky sap.  Because it has a long taproot, plucking from the soil when it is very young will give the best control.

 Redroot pigweed (Amaranthus retroflexus) grows to monstrous size, often two to three feet tall with flowers that bristle with spines.  The seeds of this annual weed are tiny and rapidly spread.  Redroot pig weed can be recognized by its characteristic reddish stalk and taproot.  Pulling it when it is young will give good control.

 Perhaps the best-known and most hated weed in our gardens is field bindweed (Convovulus arvensis).  Despite being a member of the morning glory family, there is nothing ‘glorious’ about it.  It snakes through the garden.  It entwines itself through branches, along trellises, and into every nook and cranny of the area.  Pulling this plant results in a nightmare out of Greek myth – four hydra-like plants sprouting from the single plant pulled.  Stamina is required in pulling to control this plant because it must be done repeatedly and frequently, until the energy in the root system is exhausted and the plant can no longer regenerate. 

 Gardeners should beware of the sinister puncturevine (Tribulus terrestris), also called goat’s head, due to the shape of the burs.  This plant starts off cute, with many small leaflets forming a mat across the ground.  When it becomes mature, the plant’s small burs develop a chemical on them that stays in the skin after the bur is pulled off, leaving a

painful sting that lasts for quite a while.  Any plant that is known to flatten bike tires and seriously injury livestock should be removed.

 If pulling weeds to the point of obsession is not for you, mulching garden beds is a great method of weed control.  In order to control weeds mulch should be applied to a depth of four inches across the surface of the garden.  Weed control fabric, when laid underneath the mulch may help, but research is suggesting that this fabric may limit water and air from getting to roots.

In a time when water is low and worries are high, anguished gardeners watch helplessly as cherished plants succumb to drought: trees that shaded generations of family, heirloom flowers from ancestral lands, and perennial beds are withered and brown.  We need help, we need heroes; we need Superman.  Just in time, he’s back. 

Though things looked dire, our Superman didn’t withdraw to the Fortress of Solitude; western gardeners are made of tougher stuff.  What David Salman did was forge new partnerships, bringing High Country Gardens back from the ravages of its own kryptonite:  forest fires, drought, and the economy.  Teaming with American Meadows, the beloved source for tough, xeric plants is back in business, right here in Denver at Center Greenhouse.

“I’m excited about the future; in a sense, this is embarking on a new career.  I can spend more time and effort on plants, speaking, and writing,” said Salman, who is eager to work with the Vermont-based company.  “American Meadows is letting me continue my role as Chief Horticulturist; I’m responsible for the choice of plants in the catalog.  They have the marketing expertise; I’m still able to educate people, make the selections, and keep our eco-friendly focus.  Our catalog is a little smaller, but still maintains a good breadth of selection, still focused on unusual, unique, garden-worthy plants.”

American Meadows, with its emphasis on wildflowers, was a perfect fit for purchasing High Country Gardens.  “We’re excited to have High Country Gardens as a brand, because it’s something I’ve looked up to for a while,” said Ethan Platt, President.  “We have no desire to change it; it’s too good a brand to mess with.  And David is really a unique resource – we’re eager to work with him.”

Maintaining a small research facility in Santa Fe, Salman and two of his long-time growers continue to develop new plants for the western landscape, sending cuttings and stock plants here to Center Greenhouse where the plants are grown.  With its roots in Denver firmly established, the 64-year old company is a leader in propagating and growing plants for wholesale to garden centers.  “We’ve increased staff by 10 employees just for this partnership,” says Brian Yantorno, Vice-President of Center. 

Center Greenhouses’ expertise is what Salman was searching for to take over care of plants as close to his heart as family.  “These plants need specific conditions to propagate them; you can’t do it in many places, not southern California, not the east coast.  I wanted to choose the very best wholesale growers to grow the best,” said Salman, who moved his production over the past month and a half.  “It was a huge move – imagine packing up a 2-acre house with thousands of plants, then getting them re-established in the new location.”

Celebrating their 20 years, High Country is offering 20 exciting plants, featuring their 2013 Plant of the Year, Phlox ‘Perfect Pink’ (Phlox nana).  The west Texas/New Mexico native is a showcase of the glory xeric plants possess: long blooming flowers of deep pink with a white eye on a tough, long-lived plant. 

Or snap up the new hybrid Skullcap ‘Dark Violet,’ (Scutellaria) with its masses of blooms in rich, seductive tones of reddish-blue.  “Thank goodness I’m not a dog, because if I only saw in black and white, I’d be poorer for it.  That’s what caught me about this plant – the color,” said Salman, who spent 5 years developing it for the catalog.

Hummingbird lovers will flip over Agastache ‘Desert Solstice’, a flower-packed powerhouse hybrid of blooms for our feathered friends.  The orange and pink, spikes sport 50-percent more flowers than its hybrid cousin, ‘Desert Sunrise,’ and tolerates the richer soils of amended perennial beds.

Check out highcountrygardens.com for more xeric plants, or contact them at 800-925-9387 Monday through Friday, 9 a.m. to 5 p.m. mountain time.

In an annual ritual of spring, gardeners emerge from their houses in mid-March, blinking in the thin sunlight as they peer around the landscape, assessing what needs pruning, cleaning, or mending.  All it takes to get our sap rising is for the month to turn to March, and we shrug off our winter lethargy in favor of planting the garden.

 That harbinger of spring acts like a jolt of electricity on our minds, sending a surge of energy urging us to get our hands in the soil and sow seeds.  But if you’re too quick to cave in to eagerness, you might find that your good intentions are not appreciated by the seeds you lovingly pop into the ground.  They’re not impressed by the calendar; they could care less about leprechaun and daylight savings.

 What the seeds want is warmth.  To ensure seeds sprout instead of sulk, gardeners need to plan on two things: frost date and soil temperatures.  Average date of last frost is what most rely upon to plan their plantings; it’s calculated from 30 to 40 years of data.  In Boulder the probability of frost is 50-50 on May 3, in Loveland May 4, and Longmont May 5. 

 Because it’s still possible to get frost after these dates, many gardeners prefer to use the 10-percent probability of frost date as their benchmark, which in Boulder is May 13, Loveland May 16, and Longmont May 17.  You still need to plan for protection from the odd cold snap, but the likelihood of frost is much less when waiting until mid-month.

 Yet there is a second temperature factor that Colorado gardeners shouldn’t ignore: soil.  Chilly soils will limit germination of seeds, and if the ground is both wet and cold, seeds will rot instead of sprouting. 

 Early spring vegetables vary in required soil temperatures.  Spinach and lettuce are the most tolerant, needing soil to be 35-degrees to germinate and 45-degrees or warmer to grow well.  Peas, chard, onions, mache, and parsley can grow in soils at 40-degrees, but do best in soils of 50-degrees or warmer.  Soil temperatures of 60 degrees or warmer are perfect for fava beans, beets, carrots, and leeks, while scallions, Asian greens, kale and kohlrabi like is slightly warmer, at 65-degrees.

  Can these plants germinate in slightly cooler soils?  Yes, but for them to grow rapidly and thrive – key to sweet flavor and tenderness – gardeners should pay close attention to bringing soil temperatures up.

 To do this, plastic mulches or water-filled walls are helpful.  If you’re choosing to go with warming by plastic, clear plastic works better than black at warming soil, bringing the temperature up 10 to 15 degrees in a few days. Make sure you weight down all edges of the plastic to keep it from blowing in the wind, and lay it out so that it touches the soil a week ahead of planting to give your seeds a warm start. 

 Punch holes into the plastic to sow seed if you plan on leaving the plastic in place over the season.  If you are removing the plastic once temperatures are stable, laying the sheets down in strips that can be folded back for planting space is a good way to leave the plastic between rows for a few weeks.  If using water-filled walls, place them out one week before planting to help warm the soil.

Gazing into a crystal ball for predictions on the future isn’t easy, especially when you’re talking about Mother Nature.  Vagaries in the weather have left Colorado high and dry for the past year and forecasts of no relief have spurred Denver Water into planning for spring watering restrictions. But for residents north of Denver, things aren’t quite as dire.  Not yet, anyway.

“It’s a case of we don’t know what we don’t know,” says Russ Sands, City of Boulder’s Water Conservation Program Manager, “it’s way too early to say if we’ll have restrictions.  If we have a few good storms we won’t have to; everything is so dependent on late winter early spring.” 

Coming off of a record hot season, Sands says decisions Boulder made in 2012 to ramp up treatment plants and storage kept the city in good shape to meet needs heading into 2013.  “But it’s a good reminder for people to be conscious of water use; we need people to pay attention to making sure irrigation is efficient.  Pay attention to the lawn and tackle irrigation issues.”

Northern Colorado Water Conservancy District isn’t ready to push the panic button either, says Brian Werner, Public Information Officer for the supplier of water to 33 cities and towns and 640,000 acres of farmland in northeast Colorado.  “We’re always cautioning people to wait until March and April, because those are our wettest months.”

Werner acknowledges concerns, especially after last year’s low rainfall and this winter’s piffle of snow.  After all, memories of the 2002 drought cast a shadow over the hearts of gardeners.  “2012 was the second worst runoff year for us; you don’t want to put another year like that on top of it.  But it’s followed three of the wettest years – 2009, 2010, and 2011. This is why we have water storage in this state.”

Yet storage is 25-percent below average in the District’s reservoirs, making the District cautious in its planning.  “We have some big months (of moisture) ahead of us; Mother Nature’s given us that before.  But with the way things are now, we’re casting a wary eye to the sky.”

As one of the older cities in the region, Longmont has managed its water portfolio to ride out weather downturns like the current dry spell.  Between their reservoirs and shares in the Colorado Big Thompson project, they currently have plenty of water to meet needs for 2013. 

“We track our water over a two year period and manage it conservatively, in case of dry year scenarios,” said Ken Huson, Water Resources Administrator with the city.  “We project having 144-percent of need for 2013 and 136-percent for 2014.  Our drought trigger is 135-percent or less so right now we’re not projecting going into mandatory water restrictions.”

Huson credits the long range vision of Longmont leaders in planning for water, plus aggressive water rights accrual programs and excellent storage capacity.  As the city grows so does it’s water portfolio.  “We get water rights through annexations; whenever a farmer wants land annexed for development, we require they dedicate all water rights to Longmont.  As it happens, the land around us has the senior-most water rights in the St. Vrain Basin, so we do a little bit better than other cities in getting the water we need.”

“Almost half the water used is outdoors for lawns and gardens.  We’re asking people to think about next summer now,” said Huson, “what do you need to do in spring to repair sprinklers?  And there are a lot of great seminars in spring on water conservation.”  Start by checking out the Center for Resource Conservation  for tips and classes, or check with local garden centers for their upcoming seminars.

A friend leaned close to whisper awful words in my ear, words that make many gardeners in the west sad.  “High Country Gardens has closed down,” she said, speaking of the Santa Fe, New Mexico business that has been a class act in our region and leaders in developing and promoting water-responsible plants for over 19 years.

According to an article in The Santa Fe New Mexican, High Country Gardens and its parent company, Santa Fe Greenhouses, could not overcome setbacks caused by the effects of slow consumer spending, drought, fire, and competition from big-box stores.  Attempts to downsize failed to save the nursery.

“I think what David and Ava Salman did was to bring the message of the beauty of water wise garden plants to the country,” said Pat Hayward, Executive Director of Plant Select .  “People fell in love with them; all over the country people wanted that look.  David combined beauty and water wise gardening in ways no one else has done, creating excitement.”

Salman worked closely with the Plant Select, a program dedicated to finding, promoting, and distributing plants that thrive in our harsh, dry Rocky Mountain gardens.  “We’ve been working closely with David since I first came on as Executive Director.  Blonde Ambition blue grama grass (Bouteloua gracilis ‘Blonde Ambition’) was one of his introductions, and we plan to have more of his work.  The void is huge, but he’ll continue breeding plants and discovering new, beautiful introductions.  He has an amazing eye.” 

The current economy doesn’t seem to favor any business right now, but plant industry is dear to the hearts of gardeners.  When one of our own closes down we feel the loss, especially gardeners in far flung locations that have difficulty finding water thrifty plants in their communities.  Panayoti  Kelaidis, Senior Curator and Director of Outreach for the Denver Botanic Gardens, commented on his December 6 blog, Prairie Break , that High Country Gardens’ 19 years “is a hell of a run for any nursery.”

With many plant introductions of his own, Kelaidis said he was deeply saddened by the closing of the cutting edge business.  “No question, it was the highest caliber of production, the perfect combination of quality plants for the widest market.  Theirs was a magical gift to our industry.”

Kelaidis points to Plant Select for those looking to fill the void in searching for additions to water responsible gardens.  The plants Salman helped that program introduce will continue to thrill gardeners, keeping nurseries in Colorado doing well, by and large, said the esteemed Denver Botanic Gardens’ plantsman.  “Salman helped Plant Select create a pallet of plants ideal for western gardens, plants that are low water.  It’s like our own drought insurance for our industry.  These plants are adapted, tailored to our state and growing conditions.”

Rumors abound as to whether the catalog business of the company will find new ownership, but in the meantime, gardeners, take a moment to ponder where you purchase gifts this season and next year.  Check out local garden centers and nurseries for their stock, and talk to the staff.  Over repeat visits, you’ll find they become like family, and our patronage helps them stay afloat while we all ride out the economy.

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