Container Gardening

May 13, 2011

Living in Fargo, North Dakota as a graduate student I grew hundreds of tomatoes to use for research purposes.  They grew in small pots and were mostly killed in the research conducted.  One lucky plant was hauled home in late fall, planted into a large pot (bucket) and placed in one of two small South facing windows.  It grew despite the very spartan conditions.  There were no insects to pollinate it but I would flick the flowers with my finger tips to move pollen.  The only light was from the window during the short days and the single incandescent bulb in the room.  That tomato never got very large or lush due to limited light, but did produce 23 tomatoes.  The tomatoes were about 1 ½ to 2 inches in diameter but otherwise were very normal tomatoes.  It kept producing tomatoes until the summer when garden produce became available. 

The tomato was grown as a curiosity to see how it would do in a small window. 

A few weeks ago a reader asked about vegetables in pots or small container gardens.

Try it!  You may be surprised at the success of plants.  Plants are like people, they want to grow and reproduce. Plants need only a few basic things for survival and good growth.  They are; a space for the plant to grow with support for the roots to attach to, to hold the plant, water, nutrients and sunlight.  Water, nutrients and sunlight have to be in the right amounts.  The nutrients and sunlight can actually vary quite a lot. 

The container can be just about anything.  The larger the container the more water and nutrients it will hold making life easier.  Pots, buckets, cans, wooden planters, and even a picture of an old boot showed up on the web as  a plant holder. 

Soil – Any good potting soil will be sufficient.  Potting soils are now engineered to hold extra water, provide nutrients for an extended period of time and support the plant via a good mixture of organic materials for the roots to spread out and to grow in.  Hydroponic plants can be grown in soil less environments.  Tubes filled with rocks are used and provide a place for the roots to grow and to anchor the plant.  Water and nutrients are pulsed down the tube at regular intervals so the roots can have what they need.

Most people simply buy a potting soil.  Which is best?  My local greenhouse owner “Little Red” makes his own potting mix, and of course it is the best.  My guess is it is very good but none of you can buy it unless you come to my town.  Major brands are Espoma, Fafard, and the family of products from The Scotts Company, Hyponex, Miracle Gro, Osmocote and Organic Choice garden soils and potting mixes.  My guess is they are probably all good.  Some have a total organic mix or a brand of fertilizer added to differentiate them.  For my graduate research we used 1 part soil, 1 part manure and 1 part decomposing tree bark all mixed in a grinder.  Today’s mixes mostly contain bark, peat moss and some contain a new ingredient coconut coir.  Coconut coir is the fiber from the coconut husks.  Is it a better ingredient in soil mixes?  It works and has good water holding capacity.  But so do the other organic components.  Some claims for holding water are made by adding water absorbing gels that hold lots of water and slowly give it up as the soil dries.

Water – Plants need the right amount of water.  Most plants in pots are overwatered.  Roots need to have oxygen which they get from air spaces in soils.  Overwatering fills those air spaces depriving the plant of oxygen and promoting root diseases such as pythium and phytopthora.  Only water when the soil is dry but before the plant wilts and drops leaves.  Choosing a larger pot helps keep the right amount of water for the plants.  It also makes it so you don’t have to water as frequently.  Provide a pot with holes in the bottom so excess water can drain is not essential but is a great point of success. 

Nutrients - A good soil, including most potting soils come with enough nutrients to provide those needed for several months.  If the plant becomes very large or has been supporting plants for several months, or years, you need to add nutrients.  A good water soluble fertilizer like Green Light’s Super Bloom mixed as directed and applied every two weeks will help the plant continue to thrive. Another fertilizer method is an application of Osmocote every few months to ensure good fertility.  Over fertilizing will cause a build up of nutrients to create a salty soil condition.  When soils become salty the salt holds the water not allowing water to be absorbed by the plant.

Sunlight – The right amount of light is critical and varies from one plant to another.  Most plants need a minimum of 8 hours of sun with 12 to 16 hours being ideal.  My garden gets a maximum of 10 hours of direct sun with some tree shade mixed in.  Direct sun is much better than filtered sun or other ambient light.  A few plants like ginseng, impatiens and azaleas do well with less light in shady locations. Tomatoes will grow with less light but will thrive and produce much better with direct sunlight for more than 12 hours a day.

Recently there have been several commercial variations of plants in pots.  “Square Foot Gardening,” “Topsy Turvy,” and “Potatoes in a barrel,” are examples.  They work but any container large enough to maintain the size of plant will work just as well.  Hanging baskets do very well, except many are hung in the shade so they are limited to shade loving plants.  Just get something to hold the plant, get some soil, and try the plants you want.  Follow the principles above and you will be successful.

The number one vegetable is tomatoes and they do well in pots and provide great rewards.

Sweet Corn

I normally wouldn't do this but this post is a direct cut and paste from a Harris Seed Company email sent to customers and potential customers.  I love sweet corn and couldn't write this better.  Here is plagerism except I am giving credit.  Even got the author's picture. 


Sweet Corn Genetics

Customers often ask about the different genetic types of sweet corn we offer. Here I will try to give you a quick lesson in sweet corn genetics. There are five basic genetic types of sweet corn we offer: normal sugary (su), sugary enhanced (se), synergistic se (sy), supersweet (sh) and augmented supersweet (shA).

Normal Sugary (su) is the standard sweet corn and is the one you've known from many years ago. These varieties have good corn flavor, and their quality is best if picked and eaten the same day. When picked at full maturity the quality is good, but it soon depreciates after full maturity has been reached. Most normal sugary varieties germinate quite well at soil temperatures over 55° F and grow with good vigor. The only (su) variety we still offer is Silver Queen.
Isolation note: Normal sugary varieties should be isolated from supersweet varieties (sh and shA), field corn, popcorn and ornamental corn. They may be planted beside sugary enhanced (se and sy) varieties.

Sugary Enhanced (se) varieties have elevated sugar levels, better tenderness, and higher kernel moisture levels as compared to (su) varieties. The result is a sweeter, tenderer kernel with good corn flavor that will retain its eating quality longer than a normal sugary variety. Most (se) types prefer slightly warmer soils (above 60° F) for germination. Synergistic se (sy) types are very similar to the (se) types, but the breeders have incorporated some supersweet kernels into the ears to give the varieties an extra punch of sweetness. As a whole, these types tend to have a tenderer kernel and will hold slightly longer at full maturity than the standard (se) types.
Isolation note: (Se) and (sy) varieties should be isolated from supersweet varieties (sh and shA), field corn, popcorn and ornamental corn. They may be planted beside each other and normal sugary (su) varieties.

Supersweet (sh) varieties have a shrunken gene, so named to describe the lightweight, wrinkled seed of this type. This gene raises the original levels of complex sugars and extends their flavor by slowing the conversion to simple sugars and finally to starch. Supersweets' kernel moisture is retained longer, and their ears have a much longer holding period after they reach full maturity, both on the plant and after harvest. The earlier introductions of this type had a kernel texture that was noticeably crunchier and firmer than other genetic types. However, with the introduction of Augmented Supersweet (shA) varieties, breeders have improved the tenderness considerably from what it used to be. Supersweets do not normally germinate well under less-than-ideal conditions. Wait for ideal growing conditions (soil temperatures of at least 65° F and moderate soil moisture) before planting supersweet varieties.
Isolation note: Supersweet varieties (sh and shA) may be planted beside each other but need to be isolated from all other genetic types of corn, including (su), (se) and (sy) sweet corn, field corn, popcorn and ornamental corn.

* Because corn is wind pollinated, isolation as discussed above can be achieved by separating varieties by: 250 feet of distance, an effective wind break, or 12-14 days difference in maturity time

Fertilizing a garden

April 12, 2011

Proper fertilization of a garden takes some effort.  If you are like most people you buy a bag of mixed fertilizer like a 12-12-12, or 19-19-19 and spread it over the garden.  During the summer many then water the garden with a soluble fertilizer like Green Light’s Super Bloom or Miracle Gro.  Most of the nutrients are probably wasted.  Please fertilize correctly, the wasted nutrients end up in our wastewater, streams and eventually in the ocean.  This causes local, state, and federal governments to enact rules that make it very difficult for fertilizer companies to get products to the market.  The EPA ends up getting involved with increased regulations.

The nutrients plants need are:

Nitrogen – produced quick growth and has numerous functions.

Phosphorus – is a component of proteins, phospholipids and nucleic acids.

Potassium – supports fruit development and regulates opening and closing of stomata.

Calcium – strengthens stalks and stems and influences cell membranes.

Magnesium – is essential in the chlorophyll molecule and for photosynthesis.

Sulfur – is essential in several amino acids that make proteins and enzymes.

Iron – is required for chlorophyll formation and other biochemical processes.

Manganese – influences photosynthesis and chloroplast structure and oxygen evolution.

Copper – is essential to photosynthesis and for respiration as part of cytochrome oxidase.

Zinc – is essential in NADH dehydrogenase and other photosynthesis enzymes.

Molybdenum – is required for nitrogen use, it helps transform nitrates to amino nitrogen.

Boron – regulates carbohydrate metabolism & helps cells determines cell differentiation.

Chlorides or chlorine – is required for photosynthesis.

Cobalt – A new addition to the required elements, helps legumes fix nitrogen.

Sodium – is involved in osmotic regulation and can or may do what potassium does.

Some plants use silica and selenium.  Silica may strengthen cell walls, stems and stalks.

An average crop needs about 150 units of nitrogen per year, plus a similar amount of phosphorus and potassium.  Most crops need about 20 lbs of calcium, magnesium and sulfur.  Only a few ppm are needed of the other nutrients usually called micronutrients.  Most soils can supply everything except nitrogen, phosphorus and potassium. 

Lack of nutrients generally causes stunted plants.  Shortages of certain nutrients cause color streaking in the leaves and improper flower and fruit formation.  As important as having a shortage of nutrients is not to have excessive amounts.  Excessive nutrients are wasted and can cause damage to the plant.  Too much taken up by the plant often causes leaf burn in the plant.  Soils with excessive nutrients often have a white crust develop on the surface after heavy rains dry up.  The nutrients come to the soil surface as water evaporates leaving the salt on the soil surface. 

A good rule of thumb on a garden is to add about 10 lbs of fertilizer for 1000 sq ft of garden.  Then a similar amount can be added either with irrigation or again sprinkled on the surface a couple of months later when plants really start to produce fruits and flowers.  Additional nutrients will only be wasted.  Fertilizers should contain a good amount of nitrogen to support good vegetative growth early in the season.  Later when plants are starting to bloom or produce fruit a higher amount of phosphorus and potassium may be needed.  Grass type crops such as lawns and sweet corn need more nitrogen throughout the whole growing season. 

Certain soils will be short of some micronutrients.  Iron and zinc are the most common micro nutrients that are short.  When these are needed, it is usually because the soil has too high of a pH.  This may be alleviated with additions of iron in products like Green Light’s Iron and Soil acidifier or Ironite.

As important or more important as adding fertilizer is to have the correct soil pH.  PH is a measure of the acidity of the soil.  A good soil pH is 6.5.   Low pH soils can be raised with the addition of calcium, usually in the form of lime.  Powdered lime will influence the soil faster than aggregates of lime.  Pelleted lime is easy to apply but needs to be in a form that the pellets will dissolve in water leaving a powdered lime.  Gypsum can be added to get sulfur and calcium but it neither raises nor lowers the soil pH.  Sulfur will lower soil pH but lowering pH usually takes longer and is less critical than raising the pH.

How to plant a garden and what do I need to add at planting?

April 6, 2011

How to plant a garden and what do I need to add at planting?

Where can I get information on how to plant a garden?  Most extensions bulletins are available on line, so the trip isn’t even needed.  If you are truly interested in gardening attend a Master Garden Meeting and set a goal to be a Master Gardener.  Keep reading The Garden Doc for additional information throughout the year. A few weeks ago I wrote about when to plant.  Read that first.  What do I plant was also written a few weeks ago. 

How to plant a garden?  Remember to lay out the garden on paper leaving plenty of room for plants to grow.  Carrots and beets, don’t take much room, potato plants can individually take about 9 sq ft., squash and pumpkins may have vines that run for 20 or more feet, pole beans will grow well over 6 feet high.  Lay out the garden so one plant doesn’t shade or get over run by another plant.  Leave the room at planting.   Plant the seeds with this rule of thumb; plant to a depth 4 times the size of the seed.  This means corn and beans should be planted about 1 to 1/12 inch deep potatoes about 6 inches deep but in a hill, small seeds like carrots about ¼ inch deep.  Cover with loose soil.  The biggest problem during the growing season will be weeds.  Remember hand weeding takes a lot of time.  You may want to keep the garden a manageable size.

What do I add when I plant my garden?  If you have a good soil and it is moist, add nothing.  Just plant and let the soil and nature do what they are supposed to do.  If you need fertilizer, see below.  There are some interesting new products on the market that you may be interested in trying.  Plant Starter from Advanced Biological Marketing is a micro organism mixture that may benefit plants by colonizing the roots with good microorganisms.  I bought a package at Menards.  These organisms can live in a symbiotic relationship providing nutrients to the plant and in return get sugars from the plant.  Because they colonize the plant roots they may protect the plant from deleterious microorganisms that may cause plant disease.  Inovate is a product that provides miccorhizae that do the same as above.  The only place I know to purchase this item is at Summer Winds Nursery in Arizona and Colorado.  Microorganisms that may be used are miccorhizae, bacillus, and trichoderma.  Trichoderma has been sold as T-22 in the farm and horticulture market. Look on the website of BioWorks for a trichoderma source.

Another type of product used extensively is humic or fulvic acid.  There is a lot of scientific evidence that these products work, but they don’t work in all circumstances.  If humic acid is over applied it can limit plant growth.  The American Society of Agronomy holds a meeting once a year jointly with the Crop Science Society of America and the Soil Science Society of America.  The meeting in Pittsburgh in November 2009 held a day long symposia on humic acid and microbial additives to agriculture.  Dr Rene Scoresby, formerly of LignoTech, a Borregaard company, showed a long list of studies that indicated a 5 to 10 % yield increase could be obtained using humic acid.  The conclusions showed, each soil type would need the ideal humic acid rate figured out, and that soils with problems usually showed the best response to humic acid.  Some of the data presented was produced by the USDA and Universities, others by private researchers with nothing to gain from good data.  For a gardener 1 quart is about the right amount, but each humic acid source has a different concentration. 

Next blog will be about fertilizer and how much to use.

Invasive pests on trees and ornamentals

Invasive pests on trees and ornamentals

In the last few years, several very devastating pests have arrived that infest specific plants in various locations throughout the USA.  The list includes the ficus whitefly in Florida; the hemlock woolly adelgid in hemlocks throughout the Appalachian mountains, now spreading to surrounding areas; emerald ash borer in the great lakes states spreading out as far as Tennessee, Missouri, Maryland and by the Hudson river in New York; chili thrips in Texas and other warm climates; marmorated stink bug in the Eastern US across many Midwest states; myoporium thrips in California; and others.  There is also a royal palm bug and a red palm mite that suck juice from the fronds of palm trees.  As travel and international trade continues these invasive pests will continue to invade.  This blog writer will write about some of these pests individually as the season progresses.

These pests arrive with a susceptible host plant or plants that have no resistance to a place where there are no natural predators to keep the population under control.  Ficus, or fig, hemlock, and ash trees are being killed causing heavy financial burdens to homeowners and cities who have to pay to treat or remove these dead trees.  People like trees in their yards and trees lining the streets to keep the neighborhoods fresh, cooled, and beautiful.  Trees cool the environment and shade our homes to lower air conditioning costs.  Losing the trees can reduce the value of the home.  From my youth, I loved climbing trees and climbed as high as possible until I no longer trusted the small branches to hold my few pounds of weight.

What do homeowners do to care for trees that are infested?  Number one choice of many is nothing.  Yes, you can do nothing and with ficus white fly, hemlock woolly adelgid and emerald ash borer, your tree will most likely become infested and after three to five years will die.  Then it will either fall down in a few more years or you will have to cut it down.  Trees falling can injure people and cause damage to nearby cars, homes, and other trees and shrubs.  Cutting trees down on your terms is always better than letting nature put the tree down.  The second choice is to treat the tree to kill the invading insect and save your tree.  Research has shown that you can treat the tree yourself or have it professionally treated with similar positive results.  Get the tree treated before it has declined by 40% or more and your chance of saving the tree is very high. 

Professionals may spray the tree with a high powered spray to kill insects on the outside of the tree that suck juices from the tree -  like ficus white fly and hemlock woolly adelgid.  These types of sprays may also coat the tree trunk and leaves and leave a residual spray that will kill new insects that land on the trunk or leaves for a period of time.  The second type of professional treatment is to drill holes into the tree trunk at the base and inject insecticides into the tree.  When the insect chews or sucks juice from the tree, it gets a lethal dose of insecticide and dies. 

Homeowners rarely have the type of sprayer that allows them to spray higher than about 15 feet.  Many of the insecticides used by professionals can be purchased by homeowners and used with similar results.  These can be applied by drenching or placing granules near the trunk of the tree and watering it into the soil.  These products are very effective when insects drill into the tree and eat the cambium layer.  Research has shown these applications can be just as affective as professional applications.  The cost of these pests on a mature tree may be $1500 for tree removal, $200 for a professional treatment or $20 to $40 for do-it-yourself treating. 

What would a homeowner use?  Several companies provide products.  Imidicloprid is widely used under several product names.  Those names include several brands from Bayer Advanced with the Merit brand, Bonide, Green Light and others usually with Tree & Shrub in the brand name.  Green Light markets a unique product with dinotefuran brand named Safari.  Trade names with the Safari brand include Tree & Shrub with Safari, Emerald Ash Borer Killer and Rose & Flower with Safari Insect Control.  Both imidicloprid and dinotefuran effectively control insects.  Safari gets into the tree or shrub fast because it has higher water solubility and lasts for several months in the tree.  Imidicloprid takes longer getting into the tree, moves slower in the tree but lasts for a few months longer than Safari because it has very low water solubility. 

From a personal point, I have treated an azalea bush with Tree & Shrub with Safari that had skeletonized leaves.  Two days later a bunch of little green worms were all dead and laying on the ground under the bush.  Two red pine trees with woodpeckers attacking them for the insects were treated and both have stayed alive and are recuperating nicely.  One of the red pines had about 75% of the needles lost due to insect injury.  Another tree died before I treated the living tree and the insects had eaten the cambium layer under the bark.  These products are amazing at killing insects that attack trees and shrubs. 

If you live in an area with these insects, do treat your trees.  Doing so will save the tree and maintain the value of your property.

The Garden Doc

When to plant vegetables

March 18, 2011

My NCAA men’s tournament bracket choices are showing to be less than stellar.  The sun is shining and I am itching to plant garden vegetables. I just can’t plant through the snow that is still covering my garden spot.  When is the appropriate time to plant?  Below is my personal guide with my reasons.

Early crops

Onions, peas, radishes, and most cole crops can be planted very early.  They are very hardy and can withstand a frost.  Many of these plants have inherent tolerance to light frosts.  Potatoes will freeze but they will regenerate if frostbitten and continue to grow well.  Transplanted crops like broccoli and cabbage must be acclimatized to cold weather or they will freeze.  I planted potatoes on March 17 in OH and was eating small potatoes in mid June.  I will plant the above crops as soon as I can reasonably till the soil and get the seed in without having to plant in mud.

Mid season crops

Several vegetables grow quite well in cool weather but can’t be frozen.  These are carrots, lettuce, sweet corn, red beets, swiss chard, and sometimes tomatoes and beans.  Some crops like beans can be seeded before frost ends but they germinate very slowly in cold weather and may not emerge until the threat of frost is over.  The difference is they take 3 weeks to germinate in cold weather but can germinate and emerge in 5 days in warm weather.  Sweet corn and garden peas have growing points that stay below the soil for a long time and can regenerate the plant if it freezes.  Still, any frost isn’t really good for the plant.

Late season crops

Many people would put tomatoes with this group along with sweet potatoes, okra, all melons, cucumbers, squash, pumpkins, and beans also fall into this category.  If a seed grows by pushing the seed up and the two parts of the seed become the two first leaves, it is probably a late season crop.  The growing point is above the soil line and may freeze easily. 

Most seeds, if planted very late in the fal,l would germinate and grow based on when the soil temperature is right.  The soil temperature corresponds to the season and often will allow the crop to either avoid frosts or the crop will be able to tolerate a light frost.  Vegetables that can’t tolerate frost will germinate late enough that they usually don’t emerge until after the threat of frost is over. 

Early crops grow rapidly in cool temperatures and continue to grow well in warm weather.  Late season crops stagnate in cool temperatures and grow very rapidly in warm weather.  In fact, corn in hot humid weather can grow so fast you can hear squeaking as the expanding leaves slide by the other leaves coming out of the whorl.

My plans are well laid in my head, may yours be also.

Crabgrass Control and Prevention

Sorry for missing last week, personal issues interferred.

Crabgrass Control and prevention

The second most problematic weed behind dandelions in lawns is crabgrass.  As with most problems, prevention is better than curing.  If your lawn is mostly free of crabgrass, never, never let crabgrass go to seed.  Weed seeds can last for many years in the soil.  Problems in lawns but not ornamental beds, or ornamental beds but not lawns will be a problem in both if either is left uncontrolled.

Preventing crabgrass is as simple as buying and correctly applying crabgrass preventers to your lawn and ornamental beds.  Some of the many products that may be used are (listed in order of choice by the The Garden Doc):

(I apologize to companies whose products are not listed, I intentional did not list many store brands)

Products with Dimension (dithiopyr) Can be used in lawns and ornamental beds. 

• Crabgrass Preventer with Dimension is a great product from Green Light.
• Vigoro Weed Stop Crabgrass & Weed Preventer (Dimension)
• Ace Green Turf Crabgrass Preventer & Lawn Fertilizer (Dimension) (36-3-4)
• Sta-Green Crab Ex (Dimension) 

Products with Barricade (prodiamine)

• Penningtons Crabgrass Preventer, a fertilizer with Barricade.
• Ferti-lome All Season’s Crabgrass & Weed Preventer (Barricade) (16-0-8)

Combination products

• Amaze from Green Light is a combination of Surflan (oryzalin) and Balan (benefin).  It can only be used in warm season grasses, Bermudagrass, St. Augustine grass, fescue, centipede, zoysia, and bahaigrass.  It is also excellent in all ornamental beds.
• Ferti-lome Crabgrass Preventer (Team) (20-0-3) Products with Team, a combination of Balan and Treflan (Chemical name is trifluralin)

Products with Pendelum (pendimethalin)  Can be used in lawns

• Scott’s Crabgrass Preventer - (Pendelum) (32-3-8)
• Scott’s Halts

Products with quinclorac are used for post emergence control but quinclorac does have about 45 days of residual control.  This is not sufficient for good crabgrass control.

There is one chemical, Tupersan, (siduron) that can be used when seeding new grass. 

• Preen New Lawn Crabgrass Control (Tupersan) (11-23-10)

The following describes each chemical with pros and cons (again in the order of choice by The Garden Doc).  Descriptions mostly provided by Missouri Botanical Garden

Dimension® (dithiopyr) provides superior pre-emergent control of crabgrass and many other grassy and broadleaf weeds in turf grass and other ornamental plantings. It can be applied several weeks later than other products and still give effective control. It is less of a root inhibitor that some other products so damage to new seedlings is minimal.
Barricade® (prodiamine) is one of the longest-lived of the chemicals listed and is sometimes even applied in the fall for pre-emergent control of crabgrass and many other grassy and broad leaved weeds. Since it has a long residual, grass seedling failure from this product is a common pitfall.
Amaze contains oryzalin which has the longest soil residual of these products.  Balan gives excellent control of early crabgrass and oryzalin gives very long residual control.  However, Amaze can only be used in warm season grasses.
Team® is a product that gives good early control with the Balan and longer acting control with the Treflan. Team is a traditional combination of a 2:1 ratio of Balan to Treflan. This product has a distinctive orange/yellow color but is not as prone to staining as Pendelum.
Pendelum® (pendimethylin) is another commonly used, cost effective pre-emergent crabgrass control. It has similar chemistry to Team. Its granules have a characteristic yellow/orange color and may produce staining on sidewalks and driveways. It is not particularly long lived in the soil. Pendimethylin also acts as a root inhibitor so it may have negative effectives on newly emerged turf grasses.  The Garden Docs additional comment – With high rainfall Pendelum can wash out of the crabgrass germination zone.
Tupersan® (siduron) is the only crabgrass pre-emergent chemistry that will allow cool season grasses to germinate. It is pricey and products with Tupersan are often hard to locate. It has a very short residual in the soil, so it must be followed up with another application or Dimension may be used for a follow-up application as long as all of the grass seed is germinated.  (The above chemical descriptions are mostly taken from the Missouri Botanical Garden web site and posting: http://www.mobot.org/gardeninghelp/plantfinder/pestd1.asp?ID=31)

The majority of chemicals above come from the family of chemistry called dinotroanilines.  The following all have a very yellow color and are very capable of staining.  Their staining ability is pendimethylin> trefluralin=oryzalin=benefin> prodiamine. I once dropped some pendimethylin on a white pickup tailgate and the stain drops were there for as long as I had the pickup.  Dithiopyr does not stain and is a different class of chemicals.  All products need to be activated by applying about 1/4 to ½ inch of irrigation or get lucky and have a good rain within 2 weeks of application. 

The length of time each will control crabgrass is oryzalin>prodiamine>dimension>trifluralin>pendimethylin>benefin. 

Crabgrass germinates when the soil reaches 50 degrees or warmer for 5 days at the ¼-inch level. This may occur in February in the south and early May in the northern states.  A rule of thumb is crabgrass germinates when the forsythia bloom.

Dimension, Barricade and Amaze give season-long control of crabgrass from a single application.  You need to select a rate that fits the season in your area.

Do I apply a crabgrass preventer with a fertilizer?  Answer is your choice.  Often the fertilizer used as the carrier may not be the fertilizer you should choose for your lawns needs.  Or you may make the crabgrass application at the wrong time for fertilizer in your area.

Whatever choices you make for crabgrass control, remember to always read and follow the label directions.  Many lawn care givers do nothing other than mow the crabgrass which will spread seed and insure a good crop of crabgrass next year and for several years to come.

Discussion on postemergence crabgrass control will come in late spring.