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Yard and Garden News

A friend of mine in Woodbury, MN (Washington Co.) has three peach trees bearing heavily this year. The peaches just started ripening now in early September. They are small (slightly larger than a golf ball), freestone, and delicious. From time to time I hear of a successful peach tree in Minnesota, but this is the first time I have eaten the fruit. Based on information from the Extension publication Growing Stone Fruits in Minnesota, the cultivar of these peach trees is probably ‘Reliance’, ‘Harrow Beauty’, or ‘Madison’. All are more cold-hardy than most peach cultivars, but are typically short-lived.

Does this mean that we should all grow peach trees in Minnesota? Probably not. These peach trees were planted seven years ago and have produced fruit for the last four years. This is a sign of what the warmer winters in the past 10 years may do for us in Minnesota, though if we return to “normal” Zone 3 and 4 winters peach trees are unlikely to survive. Am I going to plant a peach tree in my yard? No, but I did plant a second tree of Zestar!™, a juicy, early-bearing apple from the University of Minnesota. Enjoy the fruits from your garden, whatever they may be.

 

Having wonderfully fragrant hyacinths, daffodils, and other spring bulbs in mid to late winter is a fantastic treat that gives us the feeling that spring can’t be too far away. After getting home in the dark early evening hours of winter, I can’t help but smile as I open the front door and breathe in the rich scent of hyacinths and other spring bulbs. Potting up some of our favorite spring bulbs within the next few weeks will reward us richly as we navigate through the cold, dark winter days ahead.

Here are some tips to help get started with forcing bulbs:

Bulb selection

Although most spring bulbs can successfully be forced, it is better to choose the naturally shorter growing cultivars. This helps avoid excessively tall, leggy plants. Some easy-to-force bulbs include hyacinths, daffodils, squill (Scilla), grape hyacinths, and Dutch iris. Tulips and crocus can also be forced, but their blooms are often relatively short-lived, especially in a warm house. When shopping for bulbs select those that are firm, relatively large for the species, and do not show signs of disease.

Potting them up

Pot bulbs with the pointed ends up in a commercial potting mix or a well-draining potting medium you mix yourself. For forcing, bulbs can be planted very close together, even touching each other. Most bulbs and corms are round but tulip bulbs have a noticeable flat side. The first leaf of tulips typically grows outward from the flat side of the bulb, so place all the flat sides facing out to help make a nice symmetrical-looking pot of tulips.

All the energy the plant needs to grow and flower is stored in the bulb itself. Water newly potted bulbs and keep them at room temperature for a couple weeks before giving them their cold treatment. This allows time for a root system to begin to develop and results in a better forced plant. Relatively shallow pots can be used to save space and potting medium. It’s okay if the tips of the bulbs poke out a little bit above the potting medium surface.

It is most common to use small or medium sized pots for forcing and a single species or even cultivar in a pot. Plants of the same cultivar should bloom at about the same time and having many small or medium sized pots available allows for more containers to force over time and to place in different areas of the house. In addition, larger pots can be used for greater impact. One can plant them with many bulbs of a single cultivar or use multiple species or cultivars having different blooming times.

If you are new to forcing bulbs, I suggest making sure you have some hyacinths. They are intensely fragrant and one bulb works nicely in a 4” pot or 3 bulbs in a 6” pot.

Trick your bulbs into thinking winter has come and gone

Place pots in a cool area (between 34 and 48°F) for at least 12 weeks. The temperature must be above freezing to allow the biochemical changes to occur in the bulb and allow the necessary chilling hours to accumulate. These changes allow plants to grow vigorously once brought to a warm environment and for flower development to progress normally. The cool treatment is a natural cue to the plants that winter has come and gone and it is safe to grow and flower once temperatures begin to warm. During the cool treatment check pots periodically to make sure they remain moist. Common locations people find to provide the necessary cool treatment include a root cellar, cool corner of the basement, insulated cold frame, or refrigerator. When using the refrigerator, remove any aging produce since it could give off ethylene gas which can lead to abortion of flower buds within the bulbs.

Forcing them into flower

After bulbs have had their 12 week cool treatment, begin to bring some of the pots to warmer conditions to spur on growth and flowering. Bring them to areas with bright indirect light and a temperature of 55 to70°F. The bulbs will begin to grow rapidly and flower within a few weeks. The warmer the conditions, the greater the tendency is for stem stretching, resulting in lanky plants that may need staking. If you have enough pots you can stagger bringing them out of the cold in order to enjoy blooms over an extended period of time.

Keep soil moderately moist throughout growth and flowering. Cooler conditions will help prolong flowering. One option to help extend the enjoyment of flowering bulbs is to have them in a cooler room when you won’t be home and move them to warmer living quarters when they can be enjoyed.

What to do after flowering

After bulbs are finished flowering they can be placed in an outdoor compost pile or otherwise disposed of. Alternatively, keep them in bright light and fertilize them like a regular houseplant. This will allow the leaves to refuel the bulbs and generate new daughter bulbs and then the foliage will naturally die back. The bulbs can be planted out come spring or stored in a cool, relatively dry place and planted out in the fall.

In most homes it’s difficult to provide bulb foliage with enough bright light to allow adequate photosynthesis for strong reflowering the next season. In addition, indoor growing space for many gardeners is at a premium come spring. These things combined lead many gardeners to decide that disposing of forced bulbs after flowering is a reasonable option.

Potting up some spring bulbs now is a small investment for all the pleasure they will bring this coming winter. Pot some bulbs of your favorite species soon for early winter flowering and then more later, taking advantage of end-of-the-season sales for enjoyment in late winter.

 

Spiders are very commonly seen during late summer.  Probably the most common type is the orb weaving spiders, family Araenidae.  As their name suggests, they produce vertical, flat, round webs with strands radiating out from the center, much like a bicycle tire.  This is one of the biggest groups of spiders with species found in many sites, including around homes and in yards and gardens.  Many residents have encountered these spiders throughout Minnesota during August and September this year.

Most orb weaving spiders are moderate in size and brownish, like a barn spider, although some species such as the marble spider are brightly colored (colorful species are often orange or yellow).  The black and yellow argiope is large, with a one inch long body, and is brightly colored yellow and black.  Like most spiders, orb weaving spiders possess eight small eyes, four in the center forming a box and a pair on the right and another on the left.  Orb spiders have poor vision although they are able to detect slight differences in changes in light. 

These spiders do not rely on vision to capture prey but use the vibrations they detect in their webs to alert them when they have captured something.  Orb weaving spiders will wrap up their prey in silk then carry them away to the hub of their web or to a secure retreat to eat them at their convenience.  Nocturnal orb weaving spiders may choose to take down and eat their web in the morning and then rebuild it the next evening.  Orb weaving spiders that are active during the day similarly may reconstruct their nest in the morning.

Orb weaving spiders are harmless to people and should be left alone.  It is tempting to say ignore them but you should take the opportunity to watch these fascinating creatures.  And they are quite photogenic for anyone with a camera.  At any rate, they will die on their own as the weather becomes colder.

 

 

No, it’s not a new comic book superhero. People encountering an immature masked hunter might pause and wonder what they are looking at. This insect gets its name from its habit of covering its body with sand, lint, and other miscellaneous bits of material to camouflage itself. Underneath is a brownish insect, measuring up to about ½ inch long, but when it is covered with debris it looks positively alien, even for an insect. Adults are black, about 3/4 inch in size, and do not use this camouflage.

Masked hunters, a type of assassin bug, are predators feeding on other insects. Being hard to see would be an advantage so your prey does not detect you. Masked hunters are occasionally found indoors throughout the summer. They are essentially harmless to people, although if you pick up a masked hunter carelessly it could administer a painful bite. If you find a masked hunter in your home, just capture it and release it outside.  No other control is necessary.

 

 

Used to be that “spicy Minnesota cuisine” meant adding a dash of Tabasco to the ketchup glaze on a meatloaf. But now many Minnesotans have learned to enjoy the flavor and fire of hot peppers, thanks in part to recent immigrants who’ve brought their truly spicy cuisines with them. Peppers (Capsicum spp.) originated in South America and were unknown to the rest of the world until at least the 16th century when explorers began transporting pepper seeds back to Europe. Peppers proceeded to travel around the world and hot peppers in particular became a major component in many international cuisines.

Many hot peppers can be grown in Minnesota, though our short growing season can present a challenge. Late summer is prime time for ripening hot peppers, both the types that are eaten fresh and those that are more often used dried. Pepper plants are intolerant of frost, so if you still have peppers that you’re hoping will turn red, consider using some season-extenders such as “mini-hoophouses” - arched frames covered with poly that are placed over plants to increase heat and prevent frost damage. For larger scale production, high tunnel structures are ideal for growing peppers, since they allow earlier planting and extend the growing season into the fall. Check your local farmers market for a good assortment of peppers available now.

I recently spoke to noted Capsicum expert Dr. Hardy Eshbaugh, professor emeritus of botany at Miami University of Ohio, for help with answers to some questions about hot peppers:

Q. What makes hot peppers hot?
A. Capsaicin. It’s a chemical compound found in hot peppers. Mild peppers like bell or pimento types lack capsaicin.

Q. How are hot peppers rated for hotness?
A. The rating used for hot peppers is Scoville units. When developed in the early 1900s the ratings used human tasters to detect when they could sense “heat” in increasingly diluted extracts from the peppers. This lacked precision of course because humans have very variable abilities to sense capsaicin. The term Scoville units is still used but testing is now done with mass spectrometry.

Q. Will a hot pepper grown in Minnesota be as hot as the same variety when grown in New Mexico or India?
A. The amount of capsaicin (and thus the hotness) of a pepper variety is genetically based, so a particular pepper will be equally hot wherever it’s grown. Of course that’s assuming that you compared the peppers grown at different sites at the same maturity level, and in Minnesota the short growing season could affect a hot peppers ability to fully mature.

Q. Would a cool, rainy summer affect the hotness of peppers?
A. No, weather conditions don’t affect the genetically-based level of hotness, though again it can affect maturation. Soil type will not change hotness either.

Q. In Minnesota we typically can’t plant peppers outdoors until June, since the plants’ growth can be stunted by temperatures in the low 50s or colder. Are there any hot peppers that tolerate cooler conditions?
A. Rocoto peppers are a possibility. Most of the commonly grown hot peppers are in the species Capsicum annuum but rocoto peppers are a different species, C. pubescens, which grows at mid-elevations in the Andes Mountains. It tolerates colder temperatures but it requires a fairly long, cool growing season so you may still have a too-short season in Minnesota, at least without protection such as high tunnels.

Q. So, do you eat a lot of hot peppers?
A. No. Even though I’ve worked with hot peppers for more than 40 years I don’t enjoy eating a lot of them, at least not the ones that are so hot that you can’t taste anything after eating them.

For more information:
http://www.hort.purdue.edu/newcrop/proceedings1993/v2-132.html

Seed Savers Exchange is a source for rocoto pepper seeds:
http://www.seedsavers.org

 

 

The crowns of strawberry plants are like compressed branches. The buds at the base of each leaf on the crown can turn into either a runner or a flowering stalk.  During the long days of early summer, the buds turn into runners. The short days of August signal the plant to start making floral buds instead of runners. 

In Minnesota, strawberry plants start making flower buds around August 15th.  In cool weather, the plant will start making floral buds in early August, while hot weather can delay floral bud initiation.  Strawberry plants are currently making floral buds and will continue to do so as long as daytime temperatures climb above 50ºF. 

This period of flower initiation is critical for producing next year’s crop. Never spray the herbicide 2,4-D near strawberries between August 1 and November 1.  2,4-D interferes with floral initiation by fusing several flower buds into one large doughnut- shaped flower which will result in reduced fruit yields.

 

As temperatures cool down, the symptoms of certain viruses become more obvious to gardeners. Rose mosaic virus can easily be seen this time of year on the mature leaves of infected plants. The symptoms of this virus vary greatly from plant to plant and can include white or light colored wavy lines, netting, ring spots, and mottling. Some cultivars will show no symptoms at all even when infected. Virus infected roses can be less vigorous than healthy roses, with reduced growth and fewer flowers. They can also be more susceptible to winter injury. Regardless, many roses infected with rose mosaic virus are able to survive for years with the disease. Luckily there is no known insect vector that spreads this virus from plant to plant. Roses are typically infected through grafting of an infected plant to a healthy plant. Gardeners can choose to keep roses that are infected with this virus or to remove and replace them with healthy, more vigorous plants.

Many gardeners in the state of Minnesota are finally getting the rain they much needed. In response to these rainy cool days, gray mold has increased in many flower beds. Gray mold is caused by the fungus Botrytis cinerea, and gets its name from the powdery gray spores produced on infected plant tissue. Gray mold attacks a wide variety of flowers, fruits, and vegetables. This fungus can survive on dead plant tissue and can easily colonize aging or wounded plant parts. The gray mold fungus often first colonizes old petals or wounded tissue. From there it attacks nearby healthy stems, leaves, flowers, and other plant parts. On flowers and buds, infections start out as dark-colored flecks but can quickly grow to large dark brown to black, sunken irregular spots. The entire flower bud can be killed and the infection can continue down the stem. Infected leaves have dark irregular spots, often with dark rings inside them. The grey spores that give this disease its name can be seen on infected plant tissue when humidity is high. To reduce the effect of this disease, space plants so that good air circulation occurs in the garden. Avoid overhead irrigation, especially late afternoon and evening watering. Cut out infected tissue and dispose of it outside of the garden.

Linden leaf blotch can now be seen on littleleaf linden (Tilia cordata) and American linden (T. americana) which is also known as basswood. This disease is caused by the fungus Didymosphaeria petrakiana, and can be recognized by the dark brown to black leaf spots with a feathery edge. A yellow halo may develop around the leaf spots, and severely infected leaves may turn completely yellow and fall off. Symptoms of this disease typically do not appear until mid to late summer, even though it is believed that the spores infect the leaves in early spring. Although linden leaf spot can reduce the ornamental value of the tree, it is not considered a serious risk to the health of the tree. Gardeners who wish to reduce the amount of leaf spot in their linden tree next year should remove all fallen leaves at the end of the season and use practices that reduce moisture in the tree’s canopy. (Do not crowd plants, avoid overhead irrigation that wets the leaves, prune trees so that air moves through the canopy).

 

With the return of some rain and cooler temperatures, lawns have also returned to being green and actively growing. If your lawn did experience some dieback due to our hot and dry conditions earlier this summer, there is still some time to do reseeding or resodding to repair those areas. Cool-season lawn grasses such as Kentucky bluegrass, fine fescues and perennial ryegrass can still be planted. To help ensure their establishment before winter, it is best to have reseeding done by about the 20th of September in the Twin Cities area, sooner farther north.

Be careful not to put the garden hose away too early. Since fall is a very active time of growth for our lawns it is important to keep them adequately watered if rainfall is insufficient. With the cooler fall temperatures, a thorough watering every couple of weeks should be adequate. It is okay to let lawns dry somewhat between waterings. This will help harden them off for the winter period while keeping them out of serious drought stress.

Late summer and early fall are also good times for controlling perennial broadleaf weeds.  Since these plants are also actively growing at this time of year, herbicides (weed killers) are usually more effective at providing control. This group of plants includes common dandelion, white clover, plantain, wild violets, and creeping Charlie. While treated plants may not disappear entirely this fall, by spring, they are usually completely gone.

Even though crabgrass and other annual weedy grasses are highly visible at this time of year, now is not the time to control them. Since these plants have no frost tolerance, the first frosts of the fall will kill the plants if they are not already dead due to the completion of their annual life cycle.  It is a good idea to note where these plants have been a problem and direct preemergence weed control efforts to those areas next spring.

Late summer to early fall applications of fertilizer should be completed by about the 15th to 20th of September in the Twin Cities area. This will allow access to adequate nutrition throughout the active fall growing period while not encouraging excessive, lush growth too late into the fall. This latter condition can contribute to an increased incidence of snow mold over the winter months. Late season applications of fertilizer, particularly nitrogen, around the end of October in the Twin Cities area allow plants to store nitrogen internally and have it readily available when growth begins in the spring. This generally results in increased green color and earlier, more vigorous growth in the spring.

Late summer into early fall is a good time for these lawn care activities. Improving and maintaining a healthy lawn throughout the fall period is good for the plants this year as well as next spring.

 

 

• The end of summer is a good time to take care of some composting chores. If you have old, finished compost in the pile you can apply it to cleared garden plots or use it as mulch around asparagus, fruit trees, and ornamentals.  You may have lots of garden debris accumulated from the summer and more coming as you pull out plants at the end of the gardening season.  Fall leaves will soon be accumulating also. Start a new compost pile with the garden debris (avoiding diseased material and weeds with seeds) and dry leaves - for detailed information on building a compost pile see: http://www.extension.umn.edu/distribution/horticulture/DG3296.html

• It’s about time to plant garlic. In general, garlic in Minnesota should be planted within one to two weeks after the first killing frost (32 degrees Fahrenheit). In northern Minnesota, planting during the third to fourth week of September is recommended, while in southern Minnesota planting around the first or second week of October is recommended. For complete information on growing garlic in Minnesota see:
  http://www.extension.umn.edu/distribution/cropsystems/DC7317.html

 

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Happy gardening!

Nancy Rose
Editor
Regional Extension Educator - Horticulture

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