Red Fall Foliage - 2010

Euonymus alata has about the brightest and best hot pink color around. Much brighter than this picture gives it credit for. The plant itself is not all that exciting most of the year, but in the fall, it certainly outdoes most everything else.

Rhododendron (azalea) arborescens gradually turns from green to reddish copper. It is only just starting in this picture and would get much better in a week or so after I took its picture.

Spirea 'Gold Flame' has pretty good fall foliage most, but not every year. Most of the spireas here seem to do a pretty good job of fall color.

This is Cornus alba 'Ivory Halo'. It is a lovely shrub dogwood with green leaf centers and white margins. In the fall the white turns to pink and gives you what you see in this picture.

Cornus kousa is pretty much just a green tree after flowering in the spring. It is not a predictable fall colorer (is that a word?) but when it does color up, it gets a wonderful shade of red, almost overshadowing the Japanese maple next to which it is planted.

Acer griseum is mostly grown for its copper colored peeling bark. You can see a picture of that in the photo gallery on my website, but its fall color is a nice red, not quite as bright as Acer triflorum, but plenty nice enough.

This last one, Acer circinatum 'Oregon Fern' has to have the best and showiest fall color of anything. I know it doesn't seem to be able to decide just which color it wants to turn for fall, but no one misses it as they walk through the garden. It is not an easy tree to grow in this climate - none of the circinatums are - but we have it in a shady, rather sheltered place, and it has done well for over 10 years now.

I know I was going to post this last Friday, but I've been held hostage by Santa's elves who forced me to finish up all of my Christmas presents, and since the last animal was stuffed this morning, I am back - hopefully to be able to keep a more regular blogging schedule, at least until spring.

Jane

Fall Foliage - Things on the Yellow Side

I've spent the last few evenings finishing up some knitted things for Christmas gifts and going through all of the pictures I took this fall to share with you all. Lots of pretty things and I've sorted them by color. Tonight I'll post the ones that are more on the yellow or gold side. The one above is a Cranberry Viburnum. The leaves can vary between yellow and this reddish color.

This one is Cercidiphylum japonicum. Not only does it have parchment yellow leaves in the fall, on warm sunny days you often get the smell of brown sugar from the leaves.

This is a little known (at least I'd never heard of it when I got the plant) called Grewia biloba. It is a small shrub, at least so far, with nice fall color after green/chartreuse leaves all summer.

The Clethras don't always have nice color in the fall, but this year all of them seem to have decided to put on a nice show. We found it rather odd around here that we had such poor fall color, at least as far as trees go; only a few maples had much color at all, but things that rarely color up just had gorgeous colors

Here is a maple, Acer vitifolium - grape leafed maple that was yellowish on it's way to being quite a bit more red. Not red in the way of most of the Japanese Maples, but definitely more red that it is in the picture above.

This is one of my favorite maples, Acer tegmentosum. It needs almost full shade and a sheltered location to thrive. Ours took quite awhile to settle in, but it is now manytimes taller than I am and has wonderfully striped, almost shiny, green, grey and white bark. Once settle in, it seems to be pretty carefree. Deep rooted so I never have to give it any water, it has green leaves and then this bright yellow in the fall.

If you want unusual fall color, this Orixa japonica is about the best you can get. The leaves turn a papery white and hold that way until a heavy frost, when they drop, every last leaf, overnight. You can see the last little bit of green showing on these, but it was getting cold and I didn't want to take a chance on missing the picture. I had walked to the back of the garden every day for at least 2 weeks waiting for the perfect picture when I took this. Sometimes you just have to settle for what you can get instead of taking a chance on getting no picture at all.

Ginkgo biloba can turn this very light yellow or a deep, lemony color. If there's an early frost, like the Orixa above, every leaf will drop overnight whether they have turned yet or not. We get good fall color on them about one in four years. Gorgeous when it happens.

Tomorrow I'll post the fall colors of those trees and shrubs that are red and orange. Way too many to post them all, but I've chosen some of the nicer ones this fall. See you tomorrow.

Jane

Rhododendrons - History

Rhododendron stewartsonian (azalea)

Rhododendron 'Mandarin Lights' (azalea)

Rhododendron 'Orchid Lights' (azalea)

Rhododendron viscosum (azalea)
I just put all of the pictures up first, since basically then have nothing to do with the text today, though I guess the others from the past 4 days didn't really either. Just wanted to give you some idea of the variety of types and colors that are out there. Here is some history. As you will see, these are just a miniscule glimpse into the world of the rhododendrons.

Until fairly recently, rhododendrons were considered to be more appropriate for large estates and the prices reflected that. Plant discoveries in Asia near the end of the 19th century and the resulting hybrids opened up the possibility that ordinary gardeners could also grow them. The British were at the forefront of this change. Species were brought from China, Japan and the fringes of the Arctic Circle, from the Himalayas, Assam and Burma.

At the time of King Charles II, only one rhododendron was in cultivation, R. hirsutum, which had been introduced into England in 1656 from the Alps, and was know as the Alpine Rose.

By 1800, there were still only 12 species known. In the middle of the 1800s, Sir Joseph Hooker brought back 5 new species from the Himalayas and Robert Fortune sent back many plants from China.

By 1900 some 300 species had come to be known, but the interior of China had yet to be explored. A group of French Catholic missionaries were the first to discover what was waiting there, but Dr. Ernest Wilson made the first systematic exploration at the turn of the 19th century. From there onwards, a flood of new discoveries poured in from successive expeditions of a great company of collectors traveling through the mountains of Asia, often among hostile inhabitants, across trackless and precipitous hills, threatened by fierce storms and floods. George Forrest and Reginald Farrer died on their expedition, but their work was carried on by Captain F. Kingdon-Ward and Dr. J.F. Rock (of peony fame) and many others. This was the golden age of plant hunting in China.

Their exploration brought us new colors, new forms and a season of flowering that extended to half a year. There were dwarf plants, suitable for rock gardens, some that reached 40 feet tall, and one with leaves a yard long.

The number of known species had thus swollen to about a thousand; no doubt yet more would have been discovered if China, on becoming Communist, had not closed its borders to plant explorers (and everyone else) from the west. (my reference, printed over 50 years ago before the re-opening of the Chinese border, does not cover any newer discoveries)

We shouldn't forget, thought, that there are also rhododendrons that are native to North America, and those were also being imported into England in the 17th century. It is thought that the first deliberate hybrid was made by Michael Waterer in 1810 when he crossed Rhododendron maximum, which is native even into Canada, and Rhododendron catawbiense, from the western mountains of North Carolina. At least at the time of this book, the original specimen was still alive at Knapp Hill Nursery which he had founded. Many other hybrids followed, with the emphasis on developing plants that would be hardy in cold climates.

By the early 1900s, rhododendrons had become so easy to grow and so popular, they started replacing plants that had been popular in Victorian gardens, Laurels and Aucubas.

If you garden in northern climates, probably the most important species to you will be Rhododendron yakusimanum, originally found on the small island of Yakushima in the China Sea. Rhododendrons with this species in their genetic makeup are commonly called 'Yaks'. It is rated to survive to -5 degrees F., but it is known to survive much lower temperatures than that. For that reason, it has been used extensively in breeding for cold hardy plants. If you're looking for cold hardy rhododendrons, some varieties to look for might be Yaku Angel, Silver Bear, and Mist Maiden. Lots of them will start with 'Yaku'.

There are 2 nurseries that I would recommend highly for rhododendrons; Greer Gardens http://www.greergardens.com , whose owner Harold Greer, wrote an excellent book of the subject of rhododendrons with descriptions of hundreds of available rhododendrons and azaleas and plenty of pictures, and Rare Find Nursery http://www.rarefindnursery.com which has just a huge selection.

Enough on rhododendrons. I'll be back next week with something new. Keep warm.

Jane

Rhododendrons - Part 4

Rhododendron 'Sapho'
Another day of rhododendrons. Today I'm going to talk about some of the insects that could bother your plants. I'll repeat what I said before - we've never had any of these on our large plantings, so don't expect them and don't be scared off from growing rhododendrons because there might be something that might bother them. I just wanted people to be aware of the possibilities and how to take care of them.
Weevils are listed as a common problem. Maybe in other parts of the country. I don't know of any weevils that bother anything here. A common one on rhododendrons (to the extent that any are common) is a small black beetle about 1/4 of an inch long. They don't appear until warm weather and then they do all of their eating at night, so you may not see them, just the holes in the edges of the leaves. These won't kill your plant, just make it not quite so pretty. Orthene is rcommended to control them, but it might not be totally effective, since they may lay eggs before they start eating for the season.
Aphids may also appear on your plants. They will like to feed on tender new shoots. Orthene or Malathion will control them, but there are also other, less chemical means. A number of beneficial insects predate aphids or if the infestation is tiny, you can just pick them off or squish them.
Scale insects may appear on the bark. These suck on the bark and exude a sticky substance that turns the stems black. This is the sort of thing that also attracts aphids.

Rhododendron calendulaceum (azalea)
Caterpillars might also like to feed on newly emerging foliage. They don't seem to bother mature foliage, so as with the previous pests, you just need to keep an eye on the new growth.

Spider Mites and White Flies both feed on the undersides of the leaves. These, luckily aren't pests we see much in the garden. We have more trouble with these in the greenhouse in the winter. Spider Mites will turn the leaves a mottled brown green color. The White Flies will leave white spots where they have been sucking. Malathion will take care of both of them.

Slugs and snails can occasionally be a problem, but because of the thickness of the leaves, this isn't something you have to worry about much. Just like in hostas, those with thick leaves are not so attractive to the little slimy pests.

Rhododendron catawbiense boursault
This pretty much takes care of the planting and care of rhododendrons and azaleas. This afternoon, when I was looking for something else, I came across an older book with a chapter on the history of rhododendrons. To finish up the week, I'll share some of the more interesting parts with you tomorrow.
Jane

Rhododendrons - Part 3

As I mentioned yesterday, I can't think of any problems we have had with any of our rhododendrons and very few with our azaleas. I'll have to depend on Greer, whose book has a wealth of information. I bought the book as an aid to identifying and choosing rhododendrons and azaleas for the gardens as it is quite encyclopedic when it comes to available cultivars, but more on choosing the best plants for your garden later in the week.

There are a number of fungi who can cause you problems. If you followed the planting instructions in my last post, these shouldn't give you problems because they thrive in poorly drained soil. If you have constant standing water and the organisms get started, water splashed on the stems can cause die-back. Most fungi are most active in warm summer conditions. If fungi are a problem in your area, it is probably best to remove any fallen dead leaves and add a mulch of another kind. Bark mulch seems to have a limiting effect on these organisms. The biggest problem with the fungal diseases is that often by the time you see the symptons it's too late to do anything, especially if they have caused root rot. If you find stem die-back, you can trim out any affected branches and treat with a fungicide. If you have very hot and muggy summers, be sure to leave good air circulation around your rhododendrons when you plant them. I think half of the pruning we do here is just keeping things from growing too much into each other and cutting down on the circulating air.

Some other fungal type things you might encounter in hot humid weather are powdery mildew, which looks just like what you find on zinnias or phlox in August here. Leaf spotting from botrytis or rust is also a possibility. Often these will be a problem on injured leaves. I'll repeat again, so as not to scare anyone off from growing these gorgeous plants, I've never seen any of these things in our 10 acres of gardens where we are growing at least 50 different cultivars, and large numbers of some of those like mucronulatum and poukenense.



Rhododendron mucronulatum (azalea)

Rhododendron poukenense (azalea)

Sunburn can be a problem if the rhododendron is in too much sun. You'll see yellow leaves. These are pretty much shade loving plants, and if you see sunburn, you'll know that you need to move your rhoddy to a shadier location. If just the edges of the leaves, especially if just on one side of the plant are affected, it is probably wind burn and you need to give the plant a little bit more protections. If the burned look is on the edges of the leaves on the whole plant, it might be an overdose of fertilizer. Light green leaves usually indicate the need for more nitrogen, as in most other plants.
Tomorrow we'll go on to insect pests. Just one more pretty picture for tonight.
Jane

Rhododendron arborescens (azalea)

Rhododendrons - Part 2

Rhododendron 'David Waldman'
This is probably my favorite Rhododendron (azalea?). Can't remember which this one is and since I can't see the stamens, I'll just leave it as a pretty flower. It is named after David Waldman who owned Roslyn Nursery before he and Harriet retired.

Today's rhododendron information is on planting them and keeping them happy. According to Harold Greer who is a recognized expert on Rhododendrons, there are 3 things all rhododendrons want: A constant supply of water, well-drained soil (not a contradiction here - they need ample water and don't want to dry out, but standing water will quickly do them in, especially during hot weather), and an acid soil with a pH of 5-6 that is coarse enough for the roots to have access to oxygen.

A little more explanation on these. The water thing. Rhododendrons are one of those plants that draw water all year 'round. In places like here where the ground freezes, this presents a problem. A good mulch helps, but they also have their own defense. Remember the picture of curled leaves I posted yesterday? That's why they do it. To keep from losing water in their leaves that they aren't going to be able to replace from the frozen soil. There are treatments for the leaves that help seal them from moisture loss, but I've never tried them and find that the plants take care of themselves. In more severe climates, especially where the rhododendron will be exposed to a lot of wind, a screen of burlap is a good idea. A couple of bamboo stakes and some burlap will do the trick. Don't close the top. The plant still needs sun and whatever rain it might get on warmer days.

So how do you know if your soil will have standing water that could kill your rhododendron? You do a test that we pretty much do with anything we plant. Dig the hole and then fill it with water. If the water doesn't disappear in a few minutes, you may not have good enough drainage. (If it does drain, just fill it again. This way when the new plant is settled in, all of the surrounding soil will be nice and moist.) You need to find a happy medium between soil that doesn't drain and soil that drains too fast. You don't want stagnant, standing water, but neither do you want the plant to dry so quickly that you will have to spend all of your time watering it. If your soil is not optimum, did a much bigger hole than you need and then amend the soil before replacing it when you plant the rhododendron. The old time formula is one third bark, one third peat moss and one third garden loam. A nice coarse mix is what you're looking for, up to one third air spaces - space for water to get in to the roots and space for the extra water to drain on through and not sit and rot the roots. The late Hank Shannen (hope I spelled that right) from Rare Find Nursery, recommended cutting the root ball about a third of the way up from the bottom twice (in an X) and then spreading the root ball out sort of flat. Be sure there is plenty of new soil underneath so all of the roots are in contact with the soil. They tend to be really root bound when you buy then and this gets their roots spreading into the surrounding soil faster and helps to be sure they'll be absorbing water as well as they can and not strangling themselves as the rootbound rootball often tends to just grow in on itself and not get out where it needs to be.
Another trick I almost forgot, and this is good for any plants you buy, when you bring them home, submerge the root ball in water until air bubbles stop coming up. This makes sure it is thoroughly wet before it gets plants.

After you get the rhododendron planted, you should give it a good mulch. Eventually it will provide its own mulch as it sheds leaves, but in the beginning, you'll have to provide the mulch. Things that don't work are peat moss - dries too fast and acts like a thatched roof to shed water and see that none gets to the plant - and black plastic. Sure, plastic keeps the weeds away, but no water gets in and it will just smother the plant. Shredded leaves work well - just run the lawn mower over them. If you have lots of leaves, you can try black bag composting. Put the damp, shredded leaves in black garbage bags and leave them in an out of the way place for 6 months to a year. When finished, you will have soft, wonderful compost, all ready to mulch your plants. We also use pine needles for a lot of the things that like an acid soil. We have plenty of pine trees in our woods, so collecting them is time consuming, but wonderful for the plants. I just try to take a bit from here and a bit from there, so as not to take too much away from the pines.

Watering: Drip irrigation is wonderful and the plants love it, but if that's not an option, a hose or watering can is fine. You don't have to worry about burning the leaves on these like you do on some more delicate plants, so water them when it is convenient. Actually a summer afternoon shower that cools them off somewhat will be as much appreciated by them as it would be by you.

Just make sure to water deeply so that you don't let the rootball dry out. If that happens, sometimes it is very difficult to get it to absorb water again, so be sure to water deep and often and as long as you have amended the soil so it drains well, you really won't be able to overwater. This is especially important on newly planted ones. Our established plantings rarely get anything not provided by mother nature. There are just too many of them and once the roots get out into the surrounding soil in a few years, they can pretty much take care of themselves except during extreme drought.

Fertilizing: We don't fertilize, depending instead on compost and mulch and that seems to make healthy plants for us. Some people like to give their rhododendrons a dose of fertilizer in the spring. Either works. Whatever you like.


Rhododendron aurtrinum (azalea)More tomorrow, probably on diseases and other problems and some insects that might bother them. I'll say now that we've never had problems with anything on rhododendrons, but better to know what might happen and to know what to look for and how to fix it.
Jane

Rhododendrons

I started out to write about a very specific trait of rhododendrons - curling/rolling their leaves whenever the temperature falls much below 32 degrees. You can almost, at least here, tell when we get above freezing in the morning by looking at their leaves. These are only slightly curled; they can get into a much tighter roll as the temperature drops even more.

But there is so much to tell about rhododendrons, that I'm going to just spend a few days doing just that, now that I have a little more free time. It's too cold to work outside any more and I've finally finished all of the baskets and knitted hats and mittens that I hope to sell between now and Christmas.

I used to think that rhododendrons and azaleas were two very different plants. The flowers were similar, but, after all, they had totally different names. I now know that all azaleas are rhododendrons. Azaleas are either of the subgenus Pentanthera, the deciduous azaleas, or Tsustusti, usually evergreen. Now, by next year that might change as those in charge of such things seems to delight in confusing me, but as of now, that's where it stands.

Rhododendron (azalea) 'Satan'

Other traits of azaleas: they all have 5 lobes to their flowers and one stamen for each lobe. Rhododendrons have 2 stamens per lobe and the flowers on an azalea tend to be more tubular or funnel shaped.

Rhododendron PJM 'Olga Mezitt'

Lots more tomorrow with a bunch of other photos. Keep warm.
Jane