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Rhododendron and
Azalea News

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Summer/Fall 2008  Vol. 11  No. 2/3
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Plant Tips

Editor's Note:

It has been a long, long spring and summer and it was nearly impossible to put out a summer issue of Rhododendron and Azalea News because of two major surgeries for a "new knee" and rehab. It is joyful time to report how wonderful it is to be able to put one foot in front of the other...and to be relieved of severe pain! The doctors tell me am good for another 25 years! Glorious. A word of apology is in order...and am sorry...but things will get better.

With this in mind, and in agreement with our webmaster, Bob Weissman, we are combining things into the Fall Issue. Thanks, Bob!

 


To rake...or not to rake?

This is always the question when October rolls around, the gorgeous parades of color decide to shed their leaves, and they start to accumulate on the ground! An excellent question! The Noyo Chapter's editor posed the same question in February of 2006. Here's his viewpoint. See if you agree!

It's very common to read in gardening columns that this is a good time to tidy up our gardens. Finish getting rid of all those comfortable accommodations that the fungal spores, bacteria, and viruses have been enjoying. Rezone the areas under our rhodies and raze the slums...that is...rake up and dispose of what's left of last year's leaves.

some leaves make other trees miserable...

Host Melissa Block from National Public Radio on November 8, 2005, reports, "In recent years research has shown that the colorful autumn leaves that fall from some trees make life for other trees miserable."

some trees are good at poisoning their neighbors...

Researcher John Nielsen states, "While the segment focuses on the Eastern forests of oak, maple, and black walnut, finds walnut trees are especially good at poisoning their neighbors, so are the rhododendron trees he studies at Virginia Tech."

no apologies are in order for leaves in garden...

So, maybe we don't have to apologize for still having all those leaves out in our gardens. It's just part of our strategy to keep out the invaders! Notwithstanding this excuse for not getting it done, we may avoid feeling guilty by getting the rake out...and doing it...now.
 

To mulch...or not to mulch...how much...

The Wilmette Chapter always has the best of the best of tidbits on this and that to do in our gardens. Dr. Herb Spady offered some wonderful advice in the December 2004 newsletter. It seems appropriate to share it again.

Mulching keeps soil temperatures stable and reduces frost heaving...as well as erosion. But there are a few things to avoid...

  • the volcano mulch technique where mulch is piled up in direct contact with the trunk of the tree,
  • using chipped up plants in late summer or fall that have mature fruits, otherwise, you may have crops of weedy seedlings.
  • be aware...not all leaves make good mulches. Flat leaves like those of maples and witch hazels tend to smother the crowns of plants...but these leaves do keep out the weeds.
  • Looser, more open mulch, such as dried oak foliage is better. The potential for allelopathic interactions must also be taken into consideration, with black walnut being the classic example.
  • Coarse mulches are better than fine mulches...as the latter interfere with water an oxygen/carbon dioxide exchange. Personally, I do not like bark dust as it tends to be hydrophobic...tends to repel and not absorb water in summer.
  • In fall, wait to mulch until the lower stems of woody plants have been exposed to light chilling and a few frosts so they can develop sufficient hardiness.
  • Mulch doesn't need to be very deep…two to three inches is usually sufficient.
  • An exception is caring for the tender stuff "temperennials" of Zones 8 and 9, which should be mulched both earlier and heavier. In many cases, the entire tops will freeze out and the plant will re-grow from the roots and buried stems.
  • In early spring...remember...to remove the mulch from direct contact with crowns of perennials and trunks of small shrubs before new growth starts.

 


What is a weed?

The Eugene Chapter's newsletter for October came up with the most classic identification! You'll love this one.

Philosophers, medical doctors, physicists, parents, and siblings all have their hierarchies...but there is one true hierarch common to all. It is the 'Hierarch of Weeds'!

The definition of a weed is: something growing where it is not wanted!

Remember, even the lowly dandelion was imported from Europe as an herb. If you can't pull weeds, cut them low, and mulch over them. If they grow up through the mulch...cut them again...eventually the root will expend all of its energy and die.

Now, that is excellent advice! The thistles this year have been in an abundance, even when attacking them like a lion. Good advice! Will remember for next year!

 

Getting ready for winter!

The Shelton Chapter's newsletter is advising members just what to expect and what they can do to prepare for those winter months...just ahead of us. You may want to take note and learn a thing or two of something new.

water, water, water...

This is very important for trees and shrubs...especially if you have had a dry summer. Evergreens continue to lose moisture during the colder months...and trees and shrubs with moister soils (but not waterlogged) survive better than those in drier soils.

Some foliage droop is normal in dry weather...especially on warm afternoons...but when leaves still show signs of drooping in early morning, the plants are showing a need for water and should receive a good soaking. When air temperatures go above 95 F (or even lower for alpine types), rhododendrons and azaleas appreciate a misting to prevent desiccation of their foliage. In cold climates, watering or misting of foliage during warm days in the spring or on windy days when the roots are still frozen will help to keep rhododendrons in good condition.

need mulch...year-around...

A year-around mulch of some type of organic matter is desirable to conserve moisture and eliminate the need for cultivation. Because of their shallow roots...little or no cultivation should be done around rhododendrons.

Weeds should be carefully pulled...or in extreme cases shaved off with a sharp hoe. A fairly deep mulch of leaves, pine needles, chips, bark or other organic material will practically eliminate weed growth.

Peat moss should not be used as a mulch because it sheds water when it dries out.

The coarser the mulch...the better! As water and air are admitted while the mulch still retards evaporation by providing shade and reducing wind velocity over the roots. A mulch also helps to reduce temperature extremes in the root area.

 

October rhododendron tips

Now that the days are getting shorter, the rhodies will start going dormant. Here are a few ideas and guidelines!
  • Do not prune or fertilize now.
  • Check the flower buds which should now be formed and remove all but one bud on a terminal. This will assure a better flower truss next spring!
  • Check the leaves for symptoms of root weevil. If they are present, they leave notches along the edges of the leaves.
  • Apply some insecticides at the base of the rhodie...which is where the weevil hangs out during the day. I use Talstar™, with the generic name of bifenthrin.
  • If you like...you can hand pick the adults by going out with a flashlight at night and squashing them!
  • Fall is a good time to add or renew the mulch in your rhodie beds. Add 2 to 3 inches of bark or compost.
  • Fall is also a good time to plant or transplant rhododendrons.
  • Revive your tired lawn by over-seeding through mid-October. Sod can go in nearly any time…all winter, but be sure the soil drains well.

- Bill Stipe, Whidbey Island

 


Leaf mold...world's best mulch is free for making!

Just think, you have all the leaves in your garden, on your lawn, in your way! Now, what just are you going to do with "the stuff." Some of us have it bagged and hauled away, others may compost it, and others will dream of making "gold."

In Gardener's Supply magazine in November 2007, they wrote some interesting tips.

In Britain, leaf mold is the connoisseur's choice for mulching perennial gardens. It's easy to see why this cocoa brown, sweet-smelling, moisture-retentive mulch is so popular. The curious thing about leaf mold is that so few gardeners in the U.S. even know what it is! That's probably because here in the states there's only one way to get leaf mold...you need to make it yourself.

what is it?

Leaf mold is nothing more than partially decomposed leaves that are somewhat along the continuum between shredded leaves and humus. If you wonder what it looks like...next time you're in the woods, just kneel down and push away a small area of dry leaves. Underneath, you'll reveal a layer of leaf mold...a crumbly brown material with a pleasant, earthy scent.

benefits of leaf mold...

Leaf mold has several great attributes. The first is...that it can hold up to 500 percent its own weight in water! Besides helping to retain moisture in the soil by reducing evaporation, leaf mold also absorbs rainwater to reduce runoff…and, in hot weather...it helps cool roots and foliage.

Most leaves are slightly acidic when they fall, with a pH below 6. However, as the leaves break down into leaf mold, the pH goes up into a more neutral range. Leaf mold will not correct pH problems...but will have a moderating effect.

Over time, yearly applications of leaf mold mulch can significantly improve the quality of your soil. The result will be better water-holding capacity, a more friable texture, and an increase in beneficial soil life. Though leaves are not high in nitrogen, phosphorus, and potassium, tree roots mine calcium, magnesium, and many other trace minerals from the soil...and your garden will also benefit from these nutrients.

from leaf to leaf mold...

Unlike making regular compost, making leaf mold is a "cold" composting process. The decomposition is done primarily by fungi, rather than bacteria...and it is considerably slower. The rate of decomposition is largely determined by these key factors.

  • First, the type of leaves in your pile. Some leaves, such as oak and holly, are higher in lignin (cellulose) than others, and therefore take much longer to break down. Combining different types of leaves...like a mixed salad...is a good way to balance lignin content and also improve the quality of the finished product.
  • Moisture is another factor to keep in mind. Remember that fungi are doing the work...and they need a moist environment. An unattended pile of dry leaves could take three years or more to break down. Keep the pile covered and moist...not wet, and you may have ready-to-use leaf mold in a year.
  • Another consideration is nitrogen. Freshly fallen leaves have a carbon-to-nitrogen ratio in the range of 30 to 1, which is ideal for quick decomposition. Old leaves...including those that have been on the ground for use a few weeks...will have already lost most of their nitrogen content. If you can gather fresh leaves and get the process underway, there will still be a good amount of nitrogen to speed up the initial decomposition.

whole or shredded?

  • The easiest way to make leaf mold is to just rake your leaves into a big pile and let the pile sit there for two or three years.
  • If you aren't quite that patient…or you don't have enough room for three giant leaf piles, you'll need to shred them. Leaves break down much more quickly if they are shredded, largely because it increases the amount of surface area, which makes it easier for fungi to do their work.
  • Shredding the leaves also prevents them from packing together into stacks that repel moisture and seal out air. It also makes it easier to fit a large quantity of leaves into a relatively small space.
  • The simplest way to shred leaves is to run over them with the lawnmower a few times and then rake them up. You can also rake the leaves and run them through a leaf shredder. Or use a hand-held leaf vacuum with a shredding capability.
assembling your leaf mold pile… A leaf pile needs to be fairly substantial in size in order to retain enough moisture and heat to get finished leaf mold within 12 months. Six feet square and five feet high seems to be an ideal size. It takes about 25 trash bags pull of leaves to make a pile this large.

A second option is to pile the leaves into a wire or wood enclosure. Again, four feet or five feet square is ideal. Wet the pile thoroughly and cover it with a tarp. Check the moisture level several times during the year. It should be like a well-wrung sponge. If you live in a dry climate, you might want to line the enclosure with cardboard or plastic to help retain moisture. If you have a minute when you're checking the moisture content, use a fork to stir the leaves and incorporate a little fresh oxygen.

Another easy...yet very effective way to make leaf mold...is to pack the leaves into black trash bags. If the leaves are fresh and shredded...just moisten them...close up the bag, and poke a few holes in the sides of the bag. If the leaves are whole or dry, moisten them well and add a shovelful of garden soil, compost, or manure. Then just stash the bags out of the way for a year or two.

how to use leaf mold… Leaf mold is ready to use when it is soft and crumbly.
  • Distribute around your perennials, vegetable plants, and shrubs no more than about three inches thick. Because leaf mold retains so much moisture...be sure to keep it several inches back from the crown or base of the plant. This will help avoid pest and disease problems.
  • Can incorporate leaf mold right into the soil. Unlike raw leaves, it will not steal nitrogen from the plants around it. Safe to use in vegetable gardens and around annual flowers.
  • Add leaf mold to new garden beds.
  • Use leaf mold instead of peat moss to lighten the soil in containers.
  • Use leaf mold to enhance the soil in a shade garden.
  • Improves any soil that is too sandy or too heavy.
learn value of leaf mold... Someday...gardeners in the States may catch on to the value of leaf mold. Leaves are certainly an abundant natural resource in most parts of the country. For now...leaves are still free for the taking! Don't delay! Grab a rake...and start making your own super-premium, extra-fancy leaf mold mulch!

Editor’s note: Thanks so much to Sue Chayer of Gardener's Supply/Dutch Gardens in Burlington, Vermont, for this wonderful article. Let me tell you, the New England area has some of the most beautiful leaves in the world. Gardener's Supply has a wonderful web site, too.

 
October is the month to plant rhododendrons October is the best time to plant rhododendrons! There should be enough moisture in the soil to allow the plant a smooth transition from the pot to the ground. If you do need to water to maintain the moisture, not a lot is lost in the warm days and cool long nights.
can move rhodies, too! This is also a good time to move your rhododendrons. At this time of the year, there is time for root growth and the plants have a long time to go before they are required to perform with flowers and new growth...so give them a good chance...and plant now!
how do I begin? Guidelines:
  • Start with a good soil mix...with 25-50% organic material...such as compost, rotted manure, salt-free bark mulch, decomposed sawdust or old rotted logs. The pH should be close to 5.5.
  • Ground should be well-drained.
  • If planting in a hardpan area, digging a hole and filling it with soil may create a "wash basin" effect...it might be better to consider planting above the surface of the soil.
  • Remember...rhododendron roots spread out into the surrounding soil...not like other plants which grow roots downward...so make sure the planting area is much wider than the plant.
taking rhododendron from a pot... When you take a rhododendron plant out of the pot, you will likely find that it has tried to spread and, therefore, is quite root-bound. Don't be afraid to give those roots a good scratching and breaking up; this will encourage them to get growing.

Dust the soil with bone meal and organic fertilizer when planting. Be sure the root top stays level with the ground and the trunk is not any deeper, because rhododendrons like to have oxygen at their roots.

"place it"...not "plant it"... If moving a large rhododendron, you might find the easiest way to "plant it" is really to "place it". Make a large depression or you may want to set above the ground. Spread about 6 inches of soil where the plant is to be placed and settle the rhododendron into place. You may want to check underneath that the roots have contact with the soil or build it up in places until it sits in the most natural way...and you are satisfied with the look. Place the soil over the edges of the root ball and cover it, making sure the level covered will be the same as it was. Place soil around the root so it can spread and cover with bark mulch, making sure the trunk is not covered. Keep new plantings moist.

- Liz Murray, Cowichan Valley Rhododendron Society

Finally...it's Fall Yes, fall is a perfect time to check things out for the winter months ahead. Some people come up with the greatest of simple ideas and they share them so you...and you...and you, the readers may think. Now, why didn't I think about that. Here are some tidbits:
  • wander around the garden, and using old plastic labels or pieces of Venetian blinds, note plants to be cleaned up, dug up, or divided.
  • plastic bags with zippers...those that blankets come in...make fine mini-greenhouses for cuttings or seedlings.
  • styrofoam "peanuts" are handy for the bottom of pots...but are inclined to "fly away." Sew a few into pieces of landscape fabric...or use chunks or blocks of foam, cut to the size of the pot bottom.
  • Instead of plant labels, use small rocks. Print plant name on top and bottom of the rock so that after a year or two, when the ink has faded on top, you can reverse it and still have a name.
  • Use a 5-gal. plastic bucket for storing and carrying tools around. Glue an old-round cushion to the top so that when you need "a little rest" you have a comfortable seat on hand!
 

Something to think about...

Rekindle old friendships.
Go oft to the house of a friend,
for weeds choke up the unused path.
- Ralph Waldo Emerson

 

American Rhododendron Society
Executive Director: P.O. Box 525,  Niagara Falls, NY 14304
Ph: 416-424-1942   Fax: 905-262-1999   E-Mail: lauragrant@arsoffice.org
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