Micro-organisms in the growing medium

Micro-organisms are present everywhere; in the air, in water, on plants and in the soil. They can remain dormant for long periods in many different ways, as spores, mitochondrion (a membrane-enclosed organelle found in the cells of most organisms) or hyphae, and they can live up to several years and on a wide range of hosts. Although most people think of micro-organisms as being harmful by definition, life as we know it would not be possible without these minuscule life forms. In this article we will look at how they affect the growth of plants through their presence in the growing medium. By CANNA Research

Micro-organisms include a very broad range of species, and include bacteria, protozoa, algae and fungi. Most of these micro-organisms can multiply rapidly when the circumstances are right and they can have a major influence, both positive and negative, on the development of plants growing in the substrate. The kinds of micro- organism that appear in a given substrate will depend on a number of factors, such as the climate, the properties of the substrate, the plant species and the other organisms present in the substrate.

Micro-organisms can significantly affect the development of plants growing in the substrate, both positively and negatively. Many factors are important for micro-organisms, such as the type of growing medium. Others include the amount of oxygen, the temperature of the substrate and roots, the pH level and the salinity or EC level in the substrate. Another aspect that has quite an impact on the micro-life in the growth medium is the presence of pesticides.

Peat, coco coir, rock wool or perlite

One of the most important factors that influence micro-organisms is the type of growing medium available to them. The main differences can be found between organic substrates, such as coco coir, peat or soil, and inorganic substrates such as clay pebbles, perlite or rock wool. Micro-organisms that have a high saprophytic capacity (i.e. they live off dead organic matter) will do better in a substrate containing organic material such as peat or re-used substrate. But dead leaves lying on the surface of the substrate or infected plants with necrotic parts will do just as well.

The amount of oxygen in the substrate determines if aerobic or anaerobic micro-organisms will develop. Most plants need oxygen around their roots, so normally aerobic organisms will be present. Plants grown in a substrate with very little oxygen will usually be weaker and pathogenic anaerobic micro-organisms can benefit from that.

All organisms have an optimum growing temperature, so the temperature of the substrate and roots will affect the micro-flora around them. The average temperature and the temperature range (cold nights or a hot summer day) will determine which micro-organisms can survive, as well as the range and frequency of temperature fluctuations.

Fungus growth on rock wool cubes.

Just like plants, most micro-organisms prefer an acidity level of between pH 5.5 and 5.8. high and low pH levels, as well as pH fluctuations can disturb the development of micro-flora. still, some micro-organisms are able to grow or even flourish in extreme conditions. The salinity or EC level in the substrate will also affect the growth of the micro-organisms, and the type and composition of the salts in the growing medium also has an impact. This is especially true of salts such as Potassium chloride or Sodium chloride that can change the rhizosphere of plants and thereby the kinds of micro-life which will populate the root zone.

In inorganic substrates such as rock wool, clay pebbles or perlite, most micro-life is waterborne. These micro-organisms are introduced via watering systems, air or plants and will survive as long as the moisture level is sufficiently high, even if there are only small pockets of moisture. As with soil-borne micro-organisms, these can also be either beneficial or pathogenic.

Another aspect that has quite an impact on the micro-life in the growth medium is the presence of pesticides. These can build up in substrates or soils that are used for a prolonged period of time. Depending on the kind of pesticides – either herbicides, insecticides, fungicides or bactericides – these will influence the composition of microscopic life in the substrate.

One thing that one can rely on is the fact that micro-organisms can adapt to a range of circumstances. A well-known example is the resistance of some bacteria against antibiotics; it only takes a fractional change in their genetic material, but the effect on the resistance can be all-important.

The benefits of micro-organisms

The presence of micro-organisms can have both a positive and negative impact. As such, it is not necessary or desirable to get rid of all micro-organisms. The ability of a crop to defend itself against infections depends largely (albeit not exclusively) on the presence of micro-life in the substrate. It is difficult to quantify this benefit, however, since there are numerous factors on which the micro-life depends. The defense relates to the total microbial activity, the diversity of different groups of functional actinomycetes (rod-shaped bacteria), the total population of actinomycetes and the percentage of cellulose-decomposing actinomycetes.

If there is a good balance of micro-life in the substrate, there will most likely be less need to use pesticides and other measures, which will reduce costs. Not only are fewer and fewer pesticides actually permitted in horticulture and other applications, they are also very expensive. Plus, in a sterile substrate the most opportunistic micro-organisms will find a free space with no competitors and unlimited access to space and nutrients. These first opportunistic colonists will not necessarily be beneficial to the crop planted in the substrate. It is wiser to use the correct micro-life from the beginning to produce a healthy crop and good yield. Micro-organisms can even be used to improve the quality of reused substrates, where certain bacteria actually produce enzymes that can decompose accumulated salts.

Pythium infection on tomato roots in coco coir.

Substances that are exuded from the root system like sugars, amino acids or phenols can either attract or repel micro-organisms. The position of each species in the competition game that is continually going on between the bacteria can be influenced by these root exudates. Plants can use this to its advantage by exuding substances that attract beneficial organisms, establishing a symbiosis with a particular micro-organism. A prime example is the presence of symbiotic bacteria in the root nodules of leguminous plants such as peas or beans, which convert atmospheric nitrogen into a form that can be absorbed and used by the plant.

Another tactic is to introduce certain benign organisms to suppress pathogens. This works as follows. some micro-organisms are not very competitive and have a hard time colonizing a substrate that is already occupied by other micro-organisms. This can serve as a mechanism to get rid of pathogenic micro-organisms. By introducing beneficial micro-organisms such as mycorrhiza or trichoderma fungi into a clean substrate, the growing medium will become less inviting for pathogenic micro-organisms, thus protecting the plant from becoming infected.

Beneficial microbes compete with pathogens for nutrients or glucose and some antagonists have their own method of winning a competitive edge. For example, the fluorescent Pseudomonas bacteria can produce proteins that transform slightly soluble iron (Fe) into iron chelate, which it can then absorb much more easily. This then deprives the Fusarium fungi of the iron it needs to grow, preventing it from developing. competition for glucose can also cause microbiostasis which means that the spores of that pathogenic fungus germinate much more slowly due to a lack of energy from glucose.

Antagonistic micro-organisms can also block one or more stages of the propagation cycle of pathogens. Pseudomonas species P. Stutzeri, for example, interrupts the formation of conidia (asexual spores of several kinds of fungi) and the formation and germination of chlamydospores (thick-walled dormant spore of several kinds of fungi), but has no effect on mycelial growth (mycelial cords are capable of transferring nutrients over long distances). Pseudomonas can also produce antibiotics, which can be another tactic to remove pathogens, while other micro-organisms produce enzymes that attack the cell walls of competing species. Antagonists that produce chitinolytic enzymes have the potential to act against pathogenic fungi. It has also been found that several antagonistic organisms or closely related species can co-operate to fight a pathogen. Other antagonists simply overwhelm a pathogenic micro-organism by multiplying more rapidly and thus depriving all the competition of resources and therefore any chance of survival.

Algae development on rock wool cubes.

Pathogenic or harmful micro-organisms

Micro-life in the substrate also comes in the form of soil- or water-borne pathogens. some of these pathogens can attack over 80 different plant species and their resilience means they can be very important. There are many different harmful micro-organisms which result in a range of infections and symptoms (rotting fruits, fading, and necrosis to name but three).

Some pathogens produce micro-toxins which can attack the plant or the micro-life in the substrate. Pathogens can gain an advantage over other micro-organisms when they are able to germinate faster and are able to remain dormant for a longer period when conditions are not optimal. Pathogenic and non-pathogenic species can be very closely related, which makes it hard to use antagonists or other measures. Pathogens can fight back when they are attacked by antagonists. an example is fusarium, which can produce fusarium acid that affects the plant cells but can also suppress the production of antibiotics of Pseudomonas (this was discovered through research at Wageningen University in the Netherlands).

Balance your micro-organisms

Most infections by pathogens are in fact the result of a plant that was weak to begin with. Healthy plants are resilient and will be able to respond to an infection by micro-organisms. Provided the plant’s responses are quick and strong enough, it will be able to overcome such an infection. As such, ensuring an optimal climate and soil conditions for the crop is even more important than optimal growing conditions for (beneficial) micro-organisms.

It is crucial to get a good balance of micro-organisms in the substrate over a prolonged period of time, yet sometimes the growth cycle of a plant is simply too short to achieve this balance. Inoculating the substrate with antagonists is possible and, although the results are not always consistent, in some cases this can have a very positive effect on plant growth and health. In some cases, the results are comparable to the effect of using chemicals like fungicides, although these results may not last throughout the entire growing season.

Micro-organisms in the substrate can be a great help in suppressing plant diseases and a great deal of research is being conducted in this area of horticulture. Although this technology has still not entered the mainstream, research by the Louis Bolk Institute in the Netherlands has shown that introducing beneficial micro-organisms and or adding compost to increase the amount of micro-life can have a major effect on crop performance.

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How air temperature affects plants

Most biological processes will speed up at higher temperatures, and this can have both positive and negative effects. For example, faster growth or fruit production is one benefit, in most cases. However, the excessive respiration that occurs is adverse because it means that there is less energy for fruit development and the fruits will be smaller. Some effects are short term, while others are longer term. The plant’s assimilation balance, for example, is influenced by the temperature and is affected immediately. Flower induction, on the other hand, is determined by the climate over a much longer period.

Spider Mite – Pest

Spider Mite – Pests & Diseases

Spider mites affect many crops worldwide. There are well over 1200 species of spider mite, of which more than a hundred can be considered a pest, and about 10 are major pests. The most well known and problematic spider mite is Tetranychus urticae (common names include red spider mite and two-spotted spider mite). Their ability to reproduce extremely rapidly enables them to cause enormous damage in a short period of time. Spider mites have needle-like sucking mouthparts. They feed by penetrating the plant tissue with their mouth parts. Large populations can even cover entire plants with their web. These webs are used to move around. Because spider mites are so small, they can easily move through ventilators.

About the pest in brief

What are spider mites?: Spider mites are not insects and are in fact more closely related to spiders. They belong to a class called Arachnida.

What can you see?: Spider mites usually spin a silk webbing. When spider mites infest plant leaves, they damage the plant tissue, leaving yellowing and dead spots that coalesce until the entire leaf is eventually affected. The leaf will turn yellow, wilt and finally be shed. Some varieties of mites do not spin webs and live in the plants bud terminals, where the damage cannot be seen until the tip expands.

What can you do?: Spider mites have several natural enemies that can be used to control the population.

Biological cycle of spider mites

Each female two-spotted spider mite lays 10-20 eggs per day and 80-120 in total during its life cycle of up to four weeks. These eggs are mostly attached to the silk webbing. The six-legged larvae hatch after 3-15 days. Newly hatched larvae are almost colorless and have bright red eyes. They moult three times within 4-5 days, becoming a protonymph, then a deutonymph and finally the adult form. Both adults and nymphs have eight legs.

Symptoms of the pest

The first visible symptoms will be small yellowish or whitish specks, mainly around the midrib and larger veins of the leaves. If these spots grow bigger and merge, the empty cells give some areas of the leaf a whitish or silvery-transparent appearance.

How to prevent the pest?

To minimize the risk and rapid spread of spider mite infestations, try to keep the temperature lower (60 %), since this will slow the reproduction rate. Higher humidity is also needed for the predators of the spider mite. Keep your growing areas clean and remove all leaf litter. Adequate irrigation is important because water-stressed plants are more likely to suffer damage.

Solutions for controlling the pest

When you see spider mites (recognizable from silk webbing on top of the leaves), remove the affected leaves. Spray the plant thoroughly with a mixture of alcohol and soap. Repeat this treatment several times a week.

You can also use natural enemies: predatory mites, ladybirds, predatory bugs and lacewings.

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Whitefly – Pest

What are Whiteflies?
Whiteflies are hemipterous insects belonging to the Aleyrodidae family. They can cause considerable damage and loss of production.
What can you see?
Discolored patches on the parts of the leaf where the insects have been feeding.
What can you do?
One of the main objectives when controlling whitefly is to prevent the crop being infected by a virus that the insects can be carrying.

Whitefly are Hemiptera insects belonging to the Aleyrodidae family. They are considered a major pest for plumeria because they cause considerable damage. They feed by sucking the sap from the host plant. They are polyphagus, meaning that they feed on many different plants, and so they represent a hazard for the majority of crops, as well as feeding off wild plants and weeds that act as a reservoir for the pest.

The characteristic white color of these insects is due to a layer of white powder that covers both their bodies and their two pairs of wings.

The two species of whitefly that affect plumeria are Bemisia tabaci or tobacco whitefly and Trialeurodes vaporariorum or glasshouse whitefly. The main morphological difference that enables these insects to be distinguished from one another is the position of the wings. In B. tabaci, they are joined to the body and in T. vaporariorum they are parallel to the surface of the leaf. Furthermore, the adult and pupa of T. vaporariorum usually has a greater quantity of waxy powder than B. tabaci.

Biological cycle of Whitefly

The full life cycle of the whitefly lasts between 15 and 40 days, depending on environmental conditions, particularly the temperature, since eggs will develop into adults more quickly when the temperature is higher. The whitefly usually lays its eggs on the underside of the leaves, which the eggs stick to.

The whitefly usually lays its eggs on the underside of the leaves and the eggs stick to them by means of a pedicel. The larva or nymphs emerge from the eggs and in their first stage of development, they are mobile enough to move along the leaf until they find the right place to insert their stylus and begin to feed off the sap of the phloem, which is rich in sugars. The nymphs then pass through several more stages of development, during which they remain in the same place and continue to feed off the plant until the adult emerges from the last nymph stage. Non-fertilized eggs produce males while the fertilized eggs produce females.

Symptoms and Damage of the whitefly

The direct damage is caused to the plant when the whitefly feeds. The sucking of the sap causes discolored patches on the parts of the leaf where they have been feeding. Furthermore, as they suck out the sap, they release toxic substances into the phloem, which then spreads throughout the plant. This leads to metabolic imbalances in the plant and general weakening, chlorosis and changes to the flowers and fruit. In terms of indirect damage, the molasses excreted by the nymphs enables fungi, such as sooty mold (Capnodium sp.), to form on the leaves. This mold acts as a screen and reduces the photosynthetic capacity of the plant.

However, the most serious damage that the whitefly can cause to crops is the transmission of viruses. These include the TYLCV (Tomato yellow leaf curl virus), the ToCV (Tomato chlorosis crinivirus) or the TYMV (Tomato Yellow Mosaic Virus).

How to prevent the pest?

One of the main objectives when controlling whitefly is to avoid the crop being infected by any virus that the insects may be carrying. It is therefore important that, any weeds or remains of other plants, near the crop are removed because these can act as a habitat for whitefly. Furthermore, if a whitefly feeds off a weed that has a virus and then reaches your crop, the virus can easily spread. The use of protective barriers such as nets and covers are also a good option for preventing infestations.

Biological Control

A range of entomophagus insects, parasites, and some entomopathogenic fungi are used to control whitefly.

Most of the predators used feed on the eggs and nymphs of the whitefly. This category includes the Delphastus catalinae beetle. The chrysopidae larva and some bedbugs are also good biological controllers of this pest.

The small wasps of the Aphelinae family are parasites of the whitefly larva, where the wasps lay their eggs and they develop by feeding off their host. They are the most commonly used parasite wasps and are specific to the pest that they live off. This results in a quicker control of the pest, even though their specific nature means that they are not useful against other phytophagous insects.

Entomopathogenic fungi can also be used. This infects and grows inside the whitefly and eventually kills it. New spores emerge out from the corpse and infect other individuals. One example is the Verticillium lecanii fungus.

Whitefly (Bemisia tabaci) just emerged from its final nymphal stage, the fourth-instar nymph (pupa). Surface of hibiscus leaf. High magnification (5x) image showing the soft waxy appearance of this insect. This whitefly has a size of less than 1mm.

Cultural control measures

One of the main objectives when controlling whitefly is to avoid the crop being infected by a virus that the insect can carry.

Therefore, any weeds or remains of other plants that are near the crop should be removed as these can act as a habitat for the whitefly. Furthermore, if a whitefly feeds off a weed that contains a virus and then reaches your crop, the virus can easily be spread. The use of protective barriers such as nets and covers are also a good option for preventing infestations.

Phytosanitary treatments

The aim is to provide the plant with maximum protection during the earliest stages of the crop, thus preventing any whitefly from getting established. It is in these earliest stages that a viral infection will cause the greatest damage as the virus will spread throughout the plant and will show all its symptoms as the plant begins to produce blossom and fruit. This is why insecticides are applied to the seeds in some crops. These act systematically as soon as the seedling starts to grow and continue to protect it for several weeks.

In later stages, insecticides can be applied to the leaves to ensure the protection for the longest possible time. It should be noted that the use of non-systematic ingestion insecticides is not usually effective in combating whitefly in its larval stage, since many of the larva lack mobility. The use of insecticides that act by physical means are also a good choice to fight this larval stage.

Whitefly Pest

Hosts:

Recorded on plumeria and 38 genera of plants from 27 plant families and over 100 different species.

Common on plumeria, vegetables, ornamental, fruit and shade tree crops in Hawaii, including avocado, banana, bird-or-paradise, breadfruit, citrus, coconut, eggplant, kamani, Indian banyan, macadamia, mango, palm, paperbark, papaya, pepper, pikake, poinsettia, rose, sea grape, ti, and tropical almond.

Distribution:

Native to Central American and the Caribbean region. First reported in Hawaii in 1978 and now present on all of the major islands.

Damage:

Direct – damage caused by piercing and sucking of sap from foliage. Majority of feeding done during the first three nymphal stages. Usually insufficient to kill plants.

Indirect – damage due to accumulated honeydew and white, waxy flocculent material. The honeydew serves as a substrate for sooty mold, which blackens the leaf and decreases photosynthesis and plant vigor, and can cause disfigurement. The flocculent material is spread by the wind and can create an unsightly nuisance.

Virus transmission – damage from virus transmission can be considerable. These viruses cause over 40 diseases of vegetable and fiber crops worldwide.

Management:

This insect thrives in warm, dry weather. Heavy rains and cool temperatures may reduce populations.

Non-chemical control – five natural enemies were introduced into Hawaii from the Caribbean to control whitefly populations. One of the three coccinellid beetles (ladybugs) has proved effective with high population densities of whitefly. Two parasitic wasps have proven effective against low populations of whitefly. These biological controls generally provide adequate control to minimize damage to plants.

Chemical control – contact and systemic insecticides recommended for other pests on the same plant hosts may temporarily reduce whitefly populations. However, such insecticides may also harm whitefly predators and so should be avoided where possible.

The Spiraling Whitefly (Aleurodicus dispersus) has proven to be a nuisance and have caused damage to plumeria and native vegetation.

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Root zone temperature and plant health

There are many aspects of crop and plant production that are critical for the success of the effort. One of the most often overlooked and seldom allow ed for aspects of production centers around the temperature of the root zone. After all, it is out of sight and there is not much that can be done about it. Besides, it must be OK to hold the entire plant at the same temperature, right? Wrong; and here is why.

The Role of Potassium (K)

Potassium is a chemical element with symbol K (derived from Neo-Latin, kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name derives.

Phosphorus (P) Fallacies

A brief review of the macronutrients included in complete fertilizers: nitrogen (N) is involved in photosynthesis as part of the chlorophyll molecule and promotes vegetative growth; phosphorus (P) supports the transfer of energy throughout the plant for root development and flowering; and potassium (K) is an important part of plant metabolism, strengthening its overall health.

Plumeria Care

How To Take Care Of Your Plumeria / Frangipani

Plumeria, also known as Frangipani or Hawaiian lei flower, is an exotic tropical plant that is easy to grow. It can be easily maintained as a small tree grown in a container on the patio or in the garden.

Sun Requirements

Plumeria love sun, the more the better. Plumeria require at least 6 to 8 hours of sun to produce blooms. Plumeria will not produce bloom stems (inflorescence) without adequate sun exposure. Full sun (sunup to sundown) is BEST. Mature plants bloom from May through November, depending on where you live and the length of your growing season.

Plumeria can be grown in containers, in the ground, or containers sunk in the ground. During the months of active growth, ample sun, food, and water are essential. Healthy plumeria will grow vigorously and bloom regularly and profusely when they receive at least 6 hours of full sun per day and an ample amount of the proper fertilizers.

Water Requirements

Plumeria love lots of water, but can’t tolerate wet feet, so they must be planted in highly organic fast draining soil or in beds with adequate drainage. Clay, gumbo, and silt are examples of poor draining soils; avoid these at all costs. Plumeria love water but they need to dry out between watering. Plumeria can withstand extended periods of being dry. Small pots may need to be watered daily, while Large pots or those in the ground may not need it as often, whatever works best for you. They get used to the conditions they find themselves in. If in doubt, drier is better than wetter. Never use a saucer under your plants. Purchase a moisture meter and check your plants often until you get to know their water needs in your yard.

Insects & Disease

Plumeria have very few problems. Spider Mites, White Flies, Mealy Bugs and Scale will attack plants left too dry and/or in too much shade. Spray with liquid dish washing soap (Dawn, Sunlight, etc.) at 1-2 tablespoons/gallon or chemicals suggested for these insects. Plumeria occasionally get a “rust” fungus on the leaves in the fall, but it is rarely very harmful because the plants start to lose their leaves about the same time. “Rust” is always the result of not enough air circulation combined with too much moisture on the leaves.

Growing and Storage

The way you care for your plumeria depends on the season of the year. Bring your plants out of storage in the spring, watch them grow and bloom in the summer, prepare for dormancy and storage in the fall, and store them for the winter. Plants may be left outside if there is no damage of frost of freeze. If your nighttime temps are below 40°F you should protect you plumeria from frost.

Spring

When the nighttime temperatures begin to remain above 55°F, plumeria can be brought out of winter storage and encouraged out of dormancy. Due to conditions of storage, some root loss and desiccation of branches is expected, this is no cause for alarm. This is the time to feed, water, top dress, and/or repot. Since the plant is dormant, it will be minimally disturbed by repotting and root pruning as necessary.

Repotting and root pruning are optional and are performed as with any other container grown plant. Top dress by scraping off the loose soil and dead roots from the first couple centimeters of soil. Replace the removed soil with a mixture of compost and/or well composed cow manure.

This is a great time to give you plumeria a jump start by soaking the root ball or drenching in a mixture of Vitazyme and Carl Pool’s Root Activator.

Feed and water thoroughly using a fertilizer such as a granular slow release fertilizer with micronutrients such as Excalibur 11-11-13 or drench with a water soluble fertilizer such as Bioblast.

Place the plant in a warm and sunny location. Some people like to sink the container into the ground, but be sure it is in a raised and well drained area such as a rose bed. This promotes more vigorous growth, provides support, and prevents it from blowing over. Plumeria tips are fragile and easily snapped off when the plant blows over.

Spring is the best time for propagating plumeria. Cutting are easiest to root and will provide plenty of time for the roots to be established before dormancy in the Fall.

Summer

For plumeria, summer has arrived once a lush growth of leaves has developed. Many will bloom before developing leaves, others will not. Once the leaf growth has developed, the summer regimen of care can be followed.

As mentioned before plumeria are heavy feeders. However, in order to discourage excessive stem elongation and to promote flowering, balanced fertilizers such as Excalibur 11-11-13 with micronutrients are, once again, recommended. Carl Pool’s BR-61 are excellent choices to use early in the season as a foliar feed. (Caution, over use of a high phosphorus fertilizer such as Super Bloom or Carl Pool’s BR-61 can cause damage to you plumeria and the environment) Keep a plumeria healthy by feeding once or twice a month with Bioblast, and watering as necessary. The recommended slow release fertilizer Excalibur can be mixed directly in the top inch of the soil and then watered in. Excalibur IV will last 6 months and Excalibur IX will last 9 months.

During exceptionally hot periods, plants in above ground containers may need thorough watering as often as every other day. Drooping leaves can indicate a thirsty plant. As with all plants, check the soil before watering, if its dry for the first several inches, water thoroughly. Certain varieties of plumeria find some areas heat excessive for nominal blossom production. If this appears to be a problem, move the plant into a “shifting shade” location for better flower production and keeping quality.

As the days begin to grow shorter during August and September, some lower leaf yellowing and drop is normal. Some varieties will attempt a fall bloom cycle, if you are lucky and the weather cooperates, plumeria can still be blooming into November and December! But watch out, an early frost can damage or kill the plant.

Fall

For plumeria, fall begins once the nighttime temperature frequently begins to drop below 55°F. Studies have concluded that plumeria stop growing or slow dramatically when the average ambient temperature drops below 65°F. And the length of daylight shortens. Stop feeding about a month before Fall and reduce water to encourage the plant to go into its natural dormant period.

Some growers think that feeding after mid August may contribute to the black tip fungus problem, however this has not been proven. It is difficult to predict the weather and therefore it’s difficult to give a date by which your plumeria should be safely stored for the winter. By all means, if temperatures are expected to fall into the lower 30°sF, the plants should be protected. Most varieties can be damaged or killed by temperatures in the low 30°sF for even a few hours.

Winter

Basically, DON’T LET THEM FREEZE OR BE EXPOSED TO FROST. Plumeria go dormant in winter, and may be stored in a garage, closet, green-house, etc. They need no water or sunlight during this period — typically when night temps are consistently below 50 degrees. This will vary in different parts of the country. They may be stored in their pots (best) or bare-rooted for plants which are dug out of the ground.

During the winter plumeria require very little care. In fact winter care could be considered winter storage.

Before storage, the plumeria should be defoliated. The best way to do this is to cut each and every leaf off the plant at a point about 1/2″ from the stem. If you don’t defoliate, the leaves will yellow and fall off during storage providing a good environment for pests and fungus (as well as make a mess).

Winter Storage

It is also a good idea to spray for insects before putting you plumeria in storage.

Store the plumeria in a cool to warm, dry, and ventilated area such as a garage, storage shed, or your living room. Do not allow the roots to come in contact with concrete. Concrete will such moisture from the roots. Do not allow the tip to touch the outside walls. Temperatures should not be allowed to fall below 35°F in the storage area. During exceptionally cold periods, for example below 25°F outside, a small supplemental heater may be required for plants stored in unheated sheds. A cool greenhouse is not recommended for plumeria storage because it will tend to be too damp and thus promote black tip fungus and other fungus problems.

Some people suggest not watering plumeria at all for the entire winter, but probably a small monthly drink or fine misting does more good than harm, especially if the branches are getting desiccated and the plant is in a warm dry location.

Since a defoliated plumeria takes up considerably less space than one in full leaf, they can frequently be stacked two and three high in the storage area.

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The History and Science of Epsom Salts

This natural mineral, discovered in the well water of Epsom, England, has been used for hundreds of years, not only to fertilize plants but to treat a range of human and animal ailments. Who hasn’t soaked sore feet in it at least once?

Chemically, Epsom salts is hydrated magnesium sulfate (about 10 percent magnesium and 13 percent sulfur).

Magnesium is critical for seed germination and the production of chlorophyll, fruit, and nuts. Magnesium helps strengthen cell walls and improves plants’ uptake of nitrogen, phosphorus, and sulfur.

Sulfur, a key element in plant growth, is critical to production of vitamins, amino acids (therefore protein), and enzymes. It’s also the compound that gives vegetables such as broccoli and onions their flavors. Sulfur is seldom deficient in garden soils in North America because acid rain and commonly used animal manures contain sulfur, as do chemical fertilizers such as ammonium sulfate.

The causes and effects of magnesium deficiencies vary. Vegetables such as beans, peas, lettuce, and spinach can grow and produce good yields in soils with low magnesium levels, but plants such as tomatoes, peppers, and roses need high levels of magnesium for optimal growth. However, plants may not show the effects of magnesium deficiency until it’s severe. Some common deficiency symptoms are yellowing of the leaves between the veins, leaf curling, stunted growth, and lack of sweetness in the fruit.

Magnesium tends to be lacking in old, weathered soils with low pH, notably in the Southeast and Pacific Northwest. Soils with a pH above 7 and soils high in calcium and potassium also generally have low magnesium levels. Calcium and potassium compete with magnesium for uptake by plant roots, and magnesium often loses. Sometimes, a soil test will show adequate magnesium levels in soil, but a plant grown in that soil may still be deficient because of that competition.

Gardeners add magnesium when they apply dolomitic lime to raise the soil’s pH. However, this product (46 percent calcium carbonate, 38 percent magnesium carbonate) breaks down slowly, and the calcium can interfere with magnesium uptake. For soils with a pH above 7, many gardeners use Sul-Po-Mag (22 percent sulfur, 22 percent potassium, 11 percent magnesium) to increase magnesium. Although dolomitic lime and Sul-Po-Mag are inexpensive ways to add magnesium, Epsom salts’ advantage over them is its high solubility.

When diluted with water, and especially when applied as a foliar spray, Epsom salts can be taken up quickly by plants. Epsom salts’ magnesium content, high solubility, and ease of application as a foliar spray are the main reasons for the positive results many gardeners see in their plants.

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Too Much Nitrogen in Plumeria

Nitrogen is a key player in producing chlorophyll; this pigment absorbs sunlight for basic photosynthesis needs. Gardeners must make sure that nitrogen, one of the three macronutrients in soil, is available for root uptake by choosing the right fertilizer. Saturating a garden with high nitrogen levels, however, does not improve plant growth. In fact, it can actually harm a garden more than leaving it to its natural elemental state. Too much nitrogen in plants is apparent both above and below the topsoil.