The transition from youth to adult is associated with growing pains for most organisms. Trees are no exception. As a young tree grows to maturity, such as this Freeman maple (Acer x freemanii- cross of a silver and red maple), trunks that for years looked smooth and evenly colored can begin to split and become irregular. Don’t be alarmed. This is only natural as growth from beneath the surface places continued pressure until the surface breaks. The patterns of cracking can be regular, as for this tree, and point to regions of the truck experiencing faster growth and expansion rates.
Underneath the trunk surface of most trees are two distinct layers of dividing cells.. They actively divide in order to produce new vascular system tissue and cork. The vascular system transports water and nutrients throughout the plant. The innermost layer of dividing cells is the vascular cambium and gives rise to vascular system tissue. The vascular cambium produces new xylem cells (wood) towards the inside of the tree and phloem cells towards the outside. Xylem transports water and nutrients from the root system and xylem cells are dead at maturity, and phloem consists of live cells that transport sugars and other substances to living cells throughout the plant. The second layer of dividing cells is the cork cambium and it is just outside of the phloem. Cells of the cork cambium divide to produce cork tissue that pushes outward to provide the tree with a protective barrier.
David C. Zlesak
Love becomes a theme in many lives this time of year, especially two weeks into February. Love must have been in the air for the Swedish taxonomist Carl Linnaeus when he published the first description of our state flower, the showy lady’s slipper (Cypripedium reginae) in 1753. The “slipper” had been lost by the Roman goddess of love, Venus. She had been out with her love Adonis when they had to suddenly take shelter from a passing storm. They seized the opportunity the close quarters offered them, and after the storm passed and the lovers had gone, one of Venus’ slippers remained. A mortal spotted this lone slipper and it turned into a flower before the mortal reached it! This story led Linnaeus to combine Cyprus, Venus’ home, and pedi(l)on, meaning slipper. In keeping with the theme of love, Heinrich Pfitzer (1886) published the classification of the tropical lady’s slippers of Asia into the genus Paphiopedilum. The prefix Paphos is an acknowledgement of the city of Paphos on the island of Cyprus, where the goddess was born and came to shore and a temple was built to worship her. Though our native lady’s slippers lay dormant underneath the snow, this is a great time of year to enjoy the blossoms of the tropical lady’s slippers within our homes.
There are two genera of tropical lady’s slippers with horticultural importance: the Old World Paphiopedilum species (spp.) and the New World Phragmipedium spp. The genus Paphiopedilum includes about 77 species with distribution spanning from Nepal to China and south to New Guinea. Plants usually grow on the forest floor of tropical forests (terrestrial) with their roots penetrating the thick duff layer that holds moisture, yet drains freely. Other Paphiopedilum members grow in trees (epiphytes) or on rock ledges and cliffs (lithophytes). Many commonly cultivated Paphiopedilum spp. have relatively short, light-green leaves with darker mottling, while some others have larger, plain, bright-green leaves. One, occasionally more, flower(s) will bloom per stem, lasting for a few weeks to over a month.
Phragmipedium spp. are distributed from southern Mexico to southeastern Brazil. There are about 20 species that are nearly all terrestrial or semi-terrestrial. They have long, slender leaves that resemble large sedge plants. Many flowers bloom successively on long flower stalks, sometimes for months on end!
Light and Temperature
One of the advantages of the tropical slipper orchids is there amenability to growing in the home environment. Light can sometimes be a limiting factor inside, yet many mottled leaves species of Paphiopedilum especially grow well under relatively low-light. Position plants near an east facing window or an area of a room with bright, diffuse light. Areas with more sun, like an exposed south window, are where Phragmipedium and Paphiopedilum spp. with plain-green leaves should be grown. During the summer Paphiopedilum and Phragmipedium plants grow well with day temperatures around 85°F. For night temperatures, Paphiopedilum slippers prefer nights around 60°F, while Phragmipedium slippers prefer temperatures around 70°F . In the winter, Phragmipedium species and hybrids may be grown warm at similar summer day temperatures, but the night temperature should drop another 10 degrees to the low 60’s. Paphiopedilum species do better with a larger drop in temperature for the winter season. Day temperatures should be reduced to 75°F and the night temperature should reach 55°F. This lower night temperature in combination with shorter days is thought to promote flowering.
Water and Fertilizer
The tropical slipper orchids have different watering requirements than some of the other cultivated orchids. Since plants of the genus Phragmipedium are terrestrial plants, often growing in areas that may be flooded temporarily part of the year, these plants seasonally require more water. Watering two to three times per week in the summer and once per week in the winter is recommended. Paphiopedilum species do no require as much water as their Old World counterparts. Usually watering twice per week in the summer and once per week in the winter is adequate. When watering, water thoroughly until the point that excess water begins to drain. This is easily done by bringing placing plants in the sink and watering for 5-10 seconds. You can feed slippers with a typical water soluble houseplant fertilizer such as a 20-10-20 every other week, half-strength once a week, or quarter-strength at each watering. At least once a month pots should be leached with plain water to remove excess salts. Buildup of salts can lead to root injury.
Lady slipper orchids do best with relatively high humidity, like they experience in their native habitats. These habitats typically are relatively warm and experience frequent precipitation. A simple way to increase humidity around plants when one does not have a greenhouse or terrarium is to place them on a humidity tray. This is simply a dish from 1/2 - 2” deep that is filled with rocks (typically pebbles or small stones). Pots with slipper plants are then placed on top of the rocks and water is poured until it is just below the top of the rock. This will allow the pot to not sit in the water itself, yet as water evaporates the relative humidity will increase around the plant. This can be especially important in Minnesota households during winter months when the air is especially dry.
Media and Repotting
Both Phragmipedium spp. and Paphiopedilum spp. require free-draining growing medium. There are just about as many different recipes for tropical slipper media as there are slipper growers. Both genera benefit from a media that will allow water to drain readily, yet retain some moisture. The most commonly used component of orchid mixes is conifer bark (3-5 parts). This material will hold water, yet allow very free drainage due to the size of the bark pieces. For additional drainage, perlite and charcoal are good additions to a mix at one part each per batch. For Phragmipedium spp. and terrestrial Paphiopedilum spp., adding coarse peat (1-2 parts) in the mix will increase the water-holding capabilities of the medium. This outlines a general mix for your slippers, though custom-made or specialty mixes may be purchased at most local garden centers or orchid specialists.
For this coming Valentine’s Day, and for the rest of the winter, consider how love can be represented in your life and the lives of those you care about. Perhaps a beautiful, flowering, tropical orchid with both a unique flower and romantic story would be a great gift and tribute to love!
Groundhogs, also known as woodchucks, are common sight along Minnesota roads and in yards and gardens. Groundhogs are Minnesota’s largest squirrel. They are short and stocky with an overall brownish colored fur that is often tipped with gray. They have short, strong legs that allow them to dig extensive burrows.
Groundhogs are most active March through October; otherwise they hibernate in the winter months. In early spring females will have up to 6 offspring that stay with the mother for about 6 weeks. During the day groundhogs are active in the early morning and late afternoon. Although associated with open ground, groundhogs prefer areas near brushy cover. Hidden amongst brush or under buildings are the entrance and exit holes to the burrow. This tunnel system allows the groundhog to escape predators such as fox, coyote, hawks, and dogs. These tunnels can be over 25 feet long! The entrance and exits holes are usually 6 inches or more across.
Groundhogs are vegetarians. They eat a wide variety of vegetation including fresh plant shoots, grasses, clover, garden vegetables and tree bark from fruit trees and shrubs. It is this diet that tends to get them in trouble with people. A healthy groundhog can do quite the number on a vegetable patch or the bark of a fruit tree.
There are many ways to deal with a groundhog intruder, everything from smell and taste deterrents, changing the habitat, removal, and exclusion fences. If the groundhog is just eating grass and clover it may be simplest to just leave it alone. If it’s eating flowers or vegetables, smell and taste deterrents can sometimes be effective, especially if different types are used and rotated. Taste deterrents include soap spray and chili pepper spray. Smell deterrents include blood meal, human hair, and mothballs. Smell deterrents should be placed in small mesh bags and staked a couple inches above the ground to allow for air circulation. Both taste and smell deterrents need to be reapplied every few days. Habitat modification can make the area less hospitable to groundhogs. Remove woodpiles or scrubby underbrush that provide cover for the groundhog.
To protect a specific area, such as a vegetable garden, from animals build an exclusion fence. For a groundhog the fence should be at least 18 inches tall inches tall and buried at least 4 inches deep. Any additional height or depth will help to protect the garden. A heavy weight metal mesh, such as hardware cloth, is a good fencing material. Place support stakes in the ground every 18 inches. If there is extra height at the top of the fencing, push it outward somewhat facing away from the garden. This extra lip will help deter the occasional woodchuck with climbing tendencies.
In some areas shooting is an acceptable method of removal. In areas were firearms aren’t allowed, trapping and relocating is the best option. If you decide to trap an animal you will need a raccoon size live trap, these can be purchased or rented from most large garden stores and rental centers. Place the trap in an area where you have seen the groundhog. Place food items such as carrots, apples, and other greens around the outside of the unset trap for a couple of days. After a few days open the trap and bait it with fresh food. Remove the old food from arimages2/ound the outside. Check the trap every morning and evening. If after a few days you haven’t caught the groundhog, try fresh bait in the trap or move the trap to a new location. Once you have captured the groundhog, move the animal at least 5 miles away. Note that you need permission from the landowner before releasing any animal onto public or private land.
Although ranking third for overall yearly sales in the cut flower market, roses move to number one for Valentine’s Day. Cut rose producers try to take advantage of this window of opportunity to schedule a bumper crop of flowers to meet the Valentine demand. Plants are carefully pruned several weeks before Valentine’s Day and their growth carefully monitored in order to maximize the Valentine harvest and take advantage of higher market prices.
With increased fuel and labor costs in the United States and Europe becoming prohibitive for many domestic cut rose growers, there has been a shift to off shore cut rose production. Production has shifted from primarily greenhouses in Northern latitudes to more economical greenhouse and outdoor production systems in warmer areas of the world including Columbia, Ecuador, India, Kenya, and Israel. Faster and more affordable transportation from production regions to key markets (primarily the United States and Europe) has also helped make relocation of production possible. With this production shift, significant effort has been devoted to the breeding and development of cut rose cultivars having better adaptation to the new climates and production systems used. The market for the breeding and development of new cut roses, in fact, is much larger than that of garden or landscape roses.
In an effort to compete in the marketplace, Northern greenhouse cut rose producers need to be more creative than ever and take advantage of unique niche opportunities. Some niche opportunities that are proving successful tend to emphasize the fact nearby producers can supply a very fresh, high quality rose targeted to local or regional markets. In addition, an emphasis on excellent customer service never hurts either. Quick turnaround from harvest to florist affords the ability to grow some of the higher demand varieties that may have a shorter shelf life. For instance, roses with a strong damask or old rose fragrance that is so valued tend to have a shorter shelf life, and because of that are not typically grown for international distribution. However, a fragrant rose can command a premium price and may be feasible if grown near a key market even though it has a shorter shelf life.
The only cut rose producer/wholesale supplier left in the upper Midwest is Len Busch Roses in Plymouth, Minnesota. Part of the reason they are able to stay viable is that they invested years ago in an efficient heating system that burns waste wood products. Len Busch Roses emphasizes fragrance, quality, and freshness in their roses, customer service, and also grow a number of other high value cut flower crops including lilies and gerbera. In addition, they have worked with flower dyes to transform the flowers of a very good, long lasting white rose they produce into almost any color imaginable.
Tips for Selection and Care of Cut Roses
No matter where a cut rose was produced, here are some tips that are helpful to select high quality roses at the florist and extend their beauty once in the home or office.
Optimum flower maturity is critical for extended display life. Optimum maturity can vary depending on variety. Generally look for roses where the outermost few petals are loosening and beginning to unfurl. If the flower was cut tighter than this, it may not open properly. If the bloom has several loose opening petals when it is purchased, vase life is already compromised. Over mature blooms typically are not due to the flower being cut too late from the plant, but rather the flower has opened during an extended time in transit or time in the florist shop before the flower is purchased.
Look for flower heads placed squarely on strong, straight stems. Especially examine the neck of the stem for straightness. The neck is the portion just below the flower and above the first leaf. This is the part of the rose stem most likely to wilt if under water stress. After recovery from water stress, this section of the stem may no longer be straight and be a signal that the stem was under water stress during production. This can contribute to reduced display life.
Look for roses with foliage, stems, and flowers possessing normal color and size for the variety. Leaves and stems that are light green or yellowed and blooms with less coloration and size typical for a variety can be a sign of nutrition problems and can result in reduced vase life.
Look for roses that are free of disease and insects and have not been bruised or otherwise injured during handling.
Tips to make roses last longer
In order to extend vase life of roses it is important to 1.) promote water uptake, 2.) provide energy to sustain tissue and allow for continued growth of especially petal tissue, and 3.) slow down flower development for extended enjoyment. Use floral preservatives to help extend vase life. They contain ingredients to acidify the water, a carbohydrate (typically dextrose or sucrose) as an energy source, and anti-microbial agents.
Promote water uptake:
Avoid microbial growth in the water since it can clog vascular tissue and interfere with water uptake. Use a floral preservative because they typically contain an antimicrobial agent and acidifier, both of which limit bacterial growth. Change the solution every day or two in the vase. Avoid having foliage underwater which is subject to rotting and can increase microbial growth.
Use a sharp knife or pair of pruners to cut stems and avoid crushing vascular tissue.
Recut stems once you get the flowers home to remove ends which may have bacteria beginning to clog them. If possible, cut stems underwater or place in water soon after cutting to prevent air from getting into vascular tissue. Contrary to popular thought, cutting at an angle, although adding surface area to the cut end, does not promote greater water uptake. The vascular tissue is made up of small tubes that can be compared to straws. Even if the ends of these “straws” are cut at an angle, their diameter and water uptake ability doesn’t change.
Use luke warm water to help promote initial water uptake, especially if stems were transported out of water.
Keep your roses away from drafts that can place a higher demand for water uptake by increasing evaporation of water from their tissue.
Provide energy to sustain tissue and support growth:
Foliage and stems of cut roses can continue to photosynthesize and provide some energy to the tissue. Placing roses in indirect natural or artificial light can fuel a limited amount of photosynthesis.
Use a floral preservative because it contains a carbohydrate energy source.
Slow down flower development:
Keep in a cool place. If the room in your home or office where you would like to enjoy your roses is relatively warm, consider moving your roses to a cooler location when you are away.
Direct sunlight should be avoided because it can place a greater demand for water uptake on your roses, increase tissue temperature, and promote faster flower opening.
Commercially prepared floral preservatives are affordable, carefully balanced and prepared, ready to mix with a defined amount of water, and are easy to use. However, if you do not have access to them there are a number of ingredients commonly found in the home that can help to extend display life. A simple home floral preservative is to add to one quart of water: 2 tablespoons of lemon juice (reduces pH), 1 tablespoon sugar (carbohydrate source), and 1/2 teaspoon of bleach (suppresses microorganisms). Other ingredients people commonly mix with vase water include aspirin (acetylsalicylic acid- reduces pH) and clear soda pop (low pH, sugar, and some antimicrobial agents).
Despite the frigid weather outside, many gardeners are flipping through seed catalogues in anticipation of warmer days. A wide variety of flowers and vegetables can be started indoors long before the weather becomes warm enough to move them outside. Different types of seeds have different optimal planting dates and different growth requirements. Read this past article to learn more about starting flower and vegetable seeds indoors.
Although a flush of young green sprouts coming up in a sunny window can be a refreshing sight in the cold months ahead, it is important to start working now to prevent losses from damping-off, a common disease of seedlings. Damping off is a fungal disease caused most commonly by the fungi Rhizoctonia spp., Pythium spp., and Fusarium spp. All three of these fungi survive quite well in soil and plant debris. Since the tissue of young seedlings is soft and easy to infect, these pathogens can attack a wide variety of flowers and vegetables when they are seedlings. Damping off fungi can kill the seed before it emerges from the soil or it can attack the young stem and new leaves, resulting in tan mushy spots, pinched, rotted stems, and often complete collapse of the seedling. Once an infection has begun, the damping off fungi can move through the potting mix to infect nearby seedlings. Quite often a large section or an entire tray of seedlings is killed by damping off, resulting in few or no surviving seedlings to grow into mature plants.
Damping off is only a disease of seedlings. Once plants have mature leaves and a well developed root system, they are better able to naturally resist the damping off fungi. There is a critical period of growth where special care needs to be taken to protect sensitive seedlings. This period begins before the seeds are ever planted. One of the most import strategies of controlling damping off is preventing it in the first place. Since the damping off fungi typically survive on plant debris, soil, or in contaminated water, all pots, trays, potting mixes and other planting equipment must be sterilized prior to planting. New trays, pots, and potting mix are typically sterile. If you are reusing last year’s pots and trays, they should be soaked in a 10% bleach solution for about 30 minutes. It is best to use new unopened potting mix to start seeds. Garden soil should not be used.
Once seeds are planted, it is important to maintain a good growing environment for the seed. Potting mix should be moist but not soggy. The damping off fungi thrive in wet cool conditions. Many types of seeds, like tomatoes, need warm soil to germinate and grow well. Warming mats designed specially for heating seedling trays from below are sold through many garden catalogues and nurseries. These may be very helpful in preventing damping off especially if seeds are being grown in cool areas like a basement or garage.
Careful attention should be paid to watering seedling trays. Seeds need moisture to germinate, but too much water will encourage damping off. All pots and trays should have drainage holes to allow excess water to drain away. Seedlings should be watered with lukewarm clean water (like tap or other drinking water). Watering with cold water will slow seedling growth and favor the damping off fungi. Hoses and watering heads should be kept off the floor where they could come into contact with infected soil or plant debris. An oscillating fan can be used to increase air flow around the seedlings, but care should be taken to avoid over drying of the sensitive new plants.
Cultural practices that result in tall, thin, weak plants like growing plants under low light conditions or over fertilizing with nitrogen will result in increased damping off problems. Provide seedlings with just enough of what they truly need. A little care now will have great rewards later in the summer when you are enjoying your beautiful garden plants.
The narcissus bulb fly is an insect that attacks a variety of flower bulbs, including amaryllis, narcissus, tulip, hyacinth, and scilla. Although it looks likes a bumble bee, this insect is a type of syrphid fly (also called flower fly or hover fly). Most syrphid flies are black and yellow and smooth-skinned, mimicking bees or wasps. A narcissus bulb fly, on the other hand, is very hairy. It is about 1/2 inch long and varies in color but is generally orange or reddish brown and yellow.
While many syrphid flies are beneficial because their larvae feed on aphids, a narcissus bulb fly is one of the few in this group to damage plants. Adults lay eggs in the spring between the sheath and stem of plants. After ten to fourteen days, the eggs hatch into maggots which bore into the outer bulb scales, eventually tunneling down to the basal bulb plate. After a while they move directly into the bulb where they complete their development. This tunneling usually turns the inside of the bulb soft and mushy. This feeding often kills the bulbs - if they should survive, they will not put up very vigorous growth the following season.
Although this fly occurs throughout the U.S., it is not clear how common the narcissus bulb fly is in Minnesota. At best it appears to occur infrequently. There are 28 specimens in the Entomology Department’s insect collection but none are recorded from being collected in Minnesota. On one occasion during June, the author has seen an adult flying outdoors (although it was not correctly identified at the time) but has otherwise not encountered specimens himself or from submitted samples.
But narcissus bulb flies do occasionally damage plants as some infested bulbs have been reported. A home grower found a small percentage of her amaryllis to be infested (this was verified by rearing a larva into an adult fly). She had kept them outside in potted plants during the summer of 2006. She noticed damage later in the winter after she brought them in. These amaryllis were grown from seed so it was not a matter of buying already infested bulbs. She also found damaged amaryllis bulbs again in 2007. If you have bulbs that have wilted for no apparent reason, take a closer look, you might find the narcissus bulb fly. It is not clear whether this fly attacks the hardy bulbs planted in Minnesota gardens.
Control is difficult, especially since this is not a common pest. Your best bet is to destroy badly infested bulbs so the fly can not complete its development. If bulbs are not too far gone, it may be possible to salvage them. This can be done by cutting bulbs vertically into four or more sections making sure that each piece has at least 2 scales attached to a portion of the basal plate. Let the cut surface dry for a few hours so it can suberize (make a corky-like layer of dried cells- like what one does with potatoes) before planting. The corky layer can make pathogen attack less likely. The larger the bulb piece, the faster it can produce a new flowering plant. Be sure to plant bulb sections in new, clean potting soil that is kept moist but not soggy.
Look for tracks of rabbits and other critters in freshly fallen snow to get an idea of wildlife activity. Consider protecting valuable plants with wire or other barriers if you have not done so already. As the winter progresses, herbivores can become less and less choosy and eat plants they normally would avoid.
Continue to plan your 2008 gardens and place orders for seeds and nursery stock that you plan on getting from mail order suppliers.
Establish a game plan for pruning. Scout trees and shrubs for cankers and galls and determine which trees and shrubs many need some pruning to direct growth, remove dead or broken branches, or thin overcrowded or rubbing branches.
Continue to scout houseplants and new seedlings for insect or disease pests and intervene quickly to avoid outbreaks.
The lengthening days can stimulate overwintering plants like coleus and geranium into more active growth and allow for nice stem cuttings from which to propagate more plants. For more on taking stem cuttings please refer to this past issue.
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David C. Zlesak
Regional Extension Educator