Plant Tips

Rhododendron seed production, collecting, and growing

Dick Cavender of the Portland Chapter made a presentation on this very subject at a chapter meeting in February 2006. Dick is a pure rhodie lover. Here is his outline of procedure...which has the most unbelievable results. Might be worth your while to take note!

When I make crosses...I label them with both parents...seed parent first, and the date. I also make a list of the crosses and location.

Come late August, I walk through the garden about once a week and look at things to see how they are doing. I try to wait until the capsule started to turn brown before harvesting them.

harvest time...film canisters are BEST

At harvest, I pick the capsule, clean excess junk off, and place the capsules into a 35mm film canister...with a label!

If it is a cross, be sure to note both parents, seed parent first. The film canisters are placed in a warm room temperature...like the top of my computer desk or the top of the hot water heater or refrigerator. Be sure to remove the lid from the canister...or the seed will rot. I do not collect in plastic bags...again...rot is the problem.

Small paper bags work, too...but film canisters are best. The capsules will open in the canister and most of the seed can be shaken out with minimum effort and without breaking it up. The sections of the capsule can be pulled apart and cleaned out with a toothpick. I like to do this on a sheet of white paper. This allows me to sort out the junk as I go.

store until ready to plant...

Just store the open canisters on a shelf until am ready to plant. I have had good germination of R. occidentale seed stored in this manner for three years. It has been my experience that rhodie seed needs no special treatment...such as stratification to break dormancy.

Over the years, I have sown seed from the day the capsule opens...to April of the next year. Have decided that February/March is about the best. Since I have a greenhouse with a heated propagation bed and a mist system, I grow the seed there. I use 4-in. pots, filled three-quarters full with any good soil free mix, well soaked. I add a small amount of fertilizer, such as North Willamette Mix, 10-6-4 to this soil mix.

Cover this mix with about ½-in. of fine peat. Since am cheap, I use a mesh bottom flat to screen the peat. No-Damp-Off peat is available in 8 oz. bags...but two bags will cost about as much as 4 cubic-foot bag of regular peat. Mix it in a bucket with water to get it soaked. Sow the seed thinly...and place the open pot on the mist bench.

a mist bench substitute...

If you don't have a heated mist bench, a clear plastic "doggie bag" or salad container works fine...or place a pot in a large plastic bag. The same wet mix is used as above. The closed container is placed in an East or North window...in a warm room, or under cool white fluorescent lights.

Closed containers...or pots in a bag...will not need to be watered much as condensation will keep things damp. However, check occasionally...and mist gently...if needed. Do not let the surface of the peat dry out!

additional tips...

• Deciduous azalea seeds planted in February transplant in June...at about 2-in. tall. Do not recommend letting seedlings get that big before transplanting...but they can get away from you.
• Am forcing fuchsias during this period and fertilize every time I water. Use Peter’s 16-16-16 through a siphon mixer and the seed pots get a sprinkle every two or three days…as soon as I see green.
• If using closed plastic containers, a spray bottle with half strength soluble fertilizer...if the dose is 1 Tablespoon per gallon...use 1 teaspoon per gallon of water.
• Seedlings can be transplanted as soon as they have two true leaves…about 2-in. tall. A week or so before transplanting, prop the container open slightly to harden the plants off a bit. Watch they do not dry out! Rhodie seed is slower.
• The loose soil mix makes separating the seedlings easy...and I return them to the mist bench for a month or so to get established. If not using a mist bench, the seedlings will need some protection to get going.
• A mini-greenhouse can be made with an old aquarium, a large plastic cake container, or even a dry cleaner’s bag. If using a bag, support it with old wire hoops so it does not lie on the plants.
• I like to transplant into 2-in. pots as it saves room. My flats hold 49 pots and one or two flats is usually sufficient unless it’s something special. The loose soil mix makes separating the seedlings fairly easy. I return them in their new pots to the mist bench for a month or so to get established. If using a mini-greenhouse, after a week or two, open it gradually...and finally...remove it. They can be up potted as needed.

I have produced flowering plants in three years and have heard of other doing so in two years. Other kinds of rhododendrons may take...as long as five years...and one batch took 17 years!

Have fun!

Seed catalogues terminology...

Gail DaPont, editor, Whidbey Island Chapter newsletter, points out two things to remembering when reviewing the seed catalogs coming your way now.

When perusing seed and plant catalogs you have probably come across varieties labeled "F1" or "OP"...and wondered what does that mean.

• F1 hybrids are created by taking the pollen from the male parts of one pure, inbred plant and transferring it to the female parts of a different pure, inbred plant. The goal: to produce a new variety that is superior to either parent...larger, higher-yielding, more disease-resistant, more vigorous, among other criteria. The new variety or offspring is called an F1 hybrid. Seed from F1 hybrid plants will not likely breed true for future plants.

• On the other hand, varieties labeled OP...open pollinated...will grow true to variety name from seeds produced from the plant that you grow yourself. These may be saved and will produce the same plant in future sowings...as long as proper seed-saving procedures are followed.

Visit www.seedsave.org for detailed seed-saving instructions.

What to do with winter-injured plants

Do believe it is true...no matter where you live...one still looks forward to SPRING! And being a dedicated gardener am most concerned about the affects winter had on your plants.  Anxiously as we spot the first robins to come home, the tender blades of grass...and weeds...poking their heads up through the frozen ground, we want to know what damage could have done to our treasured rhododendrons.

Here are a few tips from the Green Garden Program, sponsored by Seattle Public Utilities.

• Don't do anything until late spring when new growth begins on the live wood and does not begin on the dead wood. Then prune to remove dead wood. Before doing anything, check to be sure the crown is alive.

• Prune properly. Do not leave stubs. Prune back to live, green, healthy wood. Prune to a bud, stem, or trunk. Give a suffering plant a chance to become healthy again.

• Prune out only dead and severely damaged wood. Do not prune live wood. The larger the leaf surface area of the plant, the better it can manufacture food and grow new tissues.

• Water properly. Make sure the plant is not further damaged by drought. Pay special attention to evergreens and plants situated under eaves. Water properly throughout the spring, summer, and fall. Do not over water.

• Fertilize properly. Fertilization is recommended if the soil lacks adequate amounts of basic plant nutrients.

• Mulch with a loose organic mulch to maintain soil moisture and protect from temperature extremes.

• On damaged fruit trees, remove as much of the developing fruit as possible to allow it to overcome the winter injury rather than produce fruit.

• The best thing you can do...for your injured tree or shrub...is to avoid further stress during the coming season by giving it special attention and care.

Tips for June gardening

Bill Stipe from Whidbey Island Chapter offers some trustworthy tips for May gardening:

If your rhododendron is getting too tall...or just plane leggy...now is the time to prune it into shape.

• Look for the dormant buds...little bumps...on the stalk and cut just above.

• Don't remove more than 1/3 of the foliage in any one season.

• Prune off any branches that are touching the ground...that is just a good place for the root weevil to climb up the plant.

• Don't leave any stubs...cut close to the main stem.

• If your rhodies are being chewed by the root weevil, now is a good time to take action.

• Have found that the beneficial nematodies (steinernema carporcapsae) are a deterrent...but will not eradicate them. A more effective treament is applying the insecticide bifenthrin. It is sold under the trade names: Talstar, Bifenthrine, Brigade, Caapture, and Zipak. Apply it as a drench to the root zone. It is not a contact spray...but will kill both the larvae and adult weevil in the soil. Watch the new leaves...when the weevil start to notch them it is time to apply Bifenthrine.

Enjoy the flowers...but also observe the new growth. On my specie rhododendrons, the emerging leaves are just as attractive as the flowers.

A three-point guide

Here are three major guides for effective gardening:

• Fertilize continual-blooming roses...like hybrid teas...in May, again June, and once more in July.

• Check your irrigation systems, soaker hoses, and drip systems to make sure they work efficiently.

• Plant summer-blooming dahlias, begonia, and gladiola bulbs now.

Dear Dr. Rhody...wrinkled leaves

We have an unusual problem with our rhodies this summer. Several of our bushes have put out new growth with wrinkled, deformed leaves that are also a light green color.

In addition, I notice a large number of our rhodies have dead leaves. One half of the leaf turns black and brittle...while the other half next to the stem is still green. This is the only summer I have noticed thee two problems. Any ideas about what is causing these problems?

- Vicki Osis

wrinkled leaves caused by freeze

Dear Vicki.

Yes, I have a couple of thoughts concerning your rhodies. The wrinkled, deformed new growth can be caused by a freeze just the leaves begin to develop. I have many plants that have shown this type of new growth. Next year the new growth will be normal...and it will be very difficult to even see the wrinkled leaves. I have been taught in seminars that there are some insect grubs that can cause the leaves to be deformed and wrinkled. I don't believe I have ever had this problem...but it can occur.

black, brittle leaves...

The black, brittle leaves are another concern. Without a sample to view, I can only guess at a possible explanation. My first guess would be...wind damage. You live in an area that has lots of wind. When new growth is affected by enough wind, all of the moisture is transpired...or evaporated from the leaf and the cells can die. This usually occurs on the tips and ends of the leaves on the outside of the plant.

Excess fertilizer is another possible cause of leaf end damage. I believe the wind is your most likely culprit.

- Dr. Rhody

Too late to prune?

We come across this question more than once...an all of the newsletters are asked the same question. The Noyo Chapter's newsletter in April 2006 featured the item again. With spring here, you may be getting those clippers out to investigate what you can do...what you should do...or just wait a while. You may find the answer below.

When and why a plant is pruned should follow a few common ideas! Here are some principles.

rhodies have dormant buds...

Rhododendrons bloom on the wood grown last year. Dominant or leading buds produce growth inhibiting hormones. Most branches have dormant buds. It takes some amount of time for these dormant buds to start growing...and then they need time to grown and harden off before it gets colder in the fall when growth slows down.

Plants tend to be less vigorous as the leaf and flower portion outgrows the root and sunlight area, i.e. they get crowded! Our desire for an "instant" garden is often not governed by the eventual size that plants attain.

pinching has awards...

Pinching off the tips of branches makes a plant more bushy. This is hard to do when you have to sacrifice the first flowers on a new plant...but in the long run you’ll likely have a more attractive shrub.

thinning out is beneficial...

Thinning out older plants is beneficial. Diseased wood can be eliminated. Spindly, leggy branches tend to be unattractive to most of us. By removing the undesirable branches, the remaining ones have less competition for light and nutrients. The plants also probably benefit from more air circulation which reduces the conditions for different airborne (fungal and viral) diseases.

time comes to do some radical changes...

As plants grow and reach maturity conditions change. The plant itself probably takes up more room than originally anticipated. Plants around it have grown...or been replaced. Except for the most experienced, farsighted gardeners, the time for some more radical action eventually comes for many of us.

You an move a plant...but this is not an easy task...if the plant is large. If you like it where it grows...then some heavy cutting can make it a smaller plant.

downsides to severe pruning...

There are some downsides to severe pruning. There is the change you have cut too far down into old wood...and the dormant buds may not be viable. You lose flowers for a couple of years while the plant is growing back. All of a sudden a large-rooted plant is sending out lots of new growth and some of our uninformed deer don't know that rhododendrons are supposed to be toxic to them.

when to start?

On the other hand, when the plant does recover you have a vigorous, newly shaped plant that is one you know you like. This heavy pruning needs to be done when the plant has time to get the dormant buds sprouting...often 6 to 8 weeks. Then there needs to be time for these growing branches to grow enough to support future years' growth. You don't want next years' growth to be borne on spindly little branches.

If you are planning to do some heavy pruning, don't spend too much more time planning. Give the plant time to get some good sturdy branches grown before it slows down next fall.

Start up the chainsaw!

To remember from your childhood...

Daffy Down Dilly has come to town,
In a yellow petticoat and a green gown.