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Why Did My Plant Die?

This is the place to read Ketzel's advice to readers' most harrowing gardening challenges from whitefly eradication to weed killer application, lawn alternatives, and bulb care. No matter where you keep your garden, check out the resources available to you locally. Find a shady spot and maybe a helping hand in the Talking Plants Gardens and Arboretums map of the United States.

Here's the Vast and Cavernous Archive of Enquiry that the Doyenne has already answered. Good clean fun for the whole family.

This week's questions:

  • Gardenia First Aid
  • Vine-In-A-Brick
  • How To Take a Rose Cutting
  • Technicolor Hydrangeas
  • Camellias In MA
  • Blue Spruce With The Blues
  • Wimpy Wisteria
  • Dry Shade
  • Hibiscus in Peril

    Gardenia First Aid

    Dear Doyenne,

    I live in Z7, the Digger Pine area of San Luis Obispo County, and have had no success keeping gardenias alive. I purchase the healthiest plant I see, make sure it is in a fairly roomy container when I transplant it into a planter mix with added peat moss. What happens is it does well during the summer and fall and then, when it starts looking like a freeze, I bring this plant in and place it in the house under a frosted sky light. According to the directions, gardenias can exist in indirect light. I also realize that gardenias do not need excess water and they do need acid-type food. I have used the Miracle Grow stuff for this type of plant and I have even tried spent coffee grounds as one successful gardenia grower has used. My plant is now dropping leaves and beginning the downward plunge. Are there any pests that could cause a well-tended plant to gradually perish? I don't seem to be able to do anything to reverse this.



    Believe it or not the best thing you can do for a gardenia is to just leave it outside. I have friends who struggled with gardenias for years indoors before they realized that the plants could stand cold above 18°F. Here in Portland, containerized gardenias are left outside through winter and thrive.

    However, since sick plants rarely recuperate, you might want to buy a new gardenia from a local nursery (but not from a florist; those have been forced in very fluffy greenhouse conditions and don't take the transition to real life well.) I suggest the Cultivars 'White Gem', 'Kleim's Hardy' (Hardy to 0°F) and Chuck Hayes, though I've heard good things about 'August Beauty' and 'Mystery' as well.

    Gardenias like to be slightly crowded in their container, they seem to bloom better that way, and they like to be fertilized only during the growing season (for you that would be April to October). Use an acid fertilizer (e.g., MirAcid), cut the dosage in half, and use it every time you water the plant. Since gardenias like to receive nutrients through their leaves, feed the water/fertilizer over the foliage. Then put that puppy out of doors.

    Best, KL

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    Dear Doyenne,
    I know, plants don't grow in bricks. My real question is whether I can remove some of the bricks, enrich or replace the soil or sand or whatever is under there, and plant a trumpet vine to grow up the back of my house so the exterior wall looms less sternly over the patio. The spot faces southwest but is shaded by mature oaks so it will only get full sun from say 11 a.m. to 1 p.m. Have I picked the right vine? Would autumn clematis do better? I'm in zone 6 in Rhode Island.

    Thank you,

    Yes, definitely take up the bricks and plant a vine there. Make sure to remove any sand that was laid down for the masonry and then try to dig through to the original soil below. You could try a trumpet vine there, but I wouldn't; not enough heat and sun. As for sweet autumn clematis, well, it's nice, but it only blooms late in the season. I'd suggest you peruse
    Joy Creek Nursery's list of clematis (it'll take you, oh, a day). I'm very fond of the viticella types for a bunch of reasons: they're long-blooming, not fussy about conditions, and bloom on new wood which means they can be pruned any time.

    Have a big old time, KL

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    How To Take a Rose Cutting

    Dear Doyenne,
    I have a question that I haven't been able to find an answer to. In the back of my house I have two climbing roses that came from cuttings from a rose bush at my grandparent's home in Alabama. My mother is over 80 and she says that that rose was there as long as she can remember. This rose in ancient. I want to send a cutting to my sister, and be able to take the rose with me whenever we move, but I have not been able to get a cutting to take. Could you send me a procedure to take a cutting from this rose to start another plant?

    Thanks, Skip

    Hi Skip,
    The best time to take rose cuttings is in July, after the current year's wood is half-hardend off. Here's how:

    Make a 4" long cutting with a diameter no more than 1/4" of an inch. Slice the bottom of the cutting at a 45 angle and dip it in rooting hormone powder. Insert the cutting into a pot (one with holes in the bottom) filled with a half perlite, half vermiculite mix (sand could be substituted for one or the other). Then mist it down thoroughly.

    Next, take a a freezer bag -- the kind that you keep leftovers in -- and invert it over the top of the pot to create a miniature greenhouse. Set the pot in a shady location -- never allow it to be in direct sunlight. Keep the container moist by watering 2 or 3 times a week.

    In 4-6 weeks, check the cutting by tugging very gently. If there's resistence, it's beginning to root. In another week, check the bottom of the pot to see if any roots are emerging. If they are, simply upend the pot and transplant into a similarly sized pot filled with regular, sterile potting soil.

    Cuttings may be sent through the mail in plastic bags with a wet paper towel.

    More than you ever wanted to know? Enjoy, KL

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    Technicolor Hydrangeas

    Dear Doyenne,
    While traveling in Europe last summer, most especially Bretagne in France, I was overwhelmed by the intense color of the hydrangeas. They all appeared to be mophead type and were the most vivid pink and purples I'd ever seen.

    I'd like to try to grow some here in the heavy clay of Northern Virginia, where I live in Springfield. I think we're zone 6. The soil is rather acid, and azaleas and rhododendrons love it here. I think hydrangeas would need partial shade to avoid being crisped by our hot humid summers.

    I haven't been able to find hydrandgeas as intensely colored (according to the pictures I've been able to find posted in the website catalogs). Are these colors owing to the local climate and soil in western Bretagne, and should I despair now, or are these varieties I just don't find here?

    Thanks for any help you can give me. I always enjoy your show and look forward to hearing updates on your fence.

    Sincerely, Ilka

    Yes, the answer to all that rich pink color is in the soil, which is clearly alkaline, since the color of a hydrangea blossom is dependent on soil pH. Alkaline soil prevents hydrangeas from taking up aluminum, the element that makes them blue. So if you would like pinker hydrangeas and you have acidic soil, the trick is to add lime to the base of the plant each fall (I'd use no more than 2 tablespoons for a 2'x3' shrub). It usually takes about 2 years for this effect to really kick in. By no means should you despair, there are tons of wonderful pink cultivars, just work the soil. BTW, another reason for the intensity of the colors in France is the relatively cool summers; we get the same effect here in the Maritime Pacific Northwest. And in case you didn't already know, hydrangeas prefer shade, especially in hot summer climates such as yours, plus rich soil that is never allowed to dry out.

    Hope this helps, KL

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    Camellias In MA

    Dear Doyenne,
    I have a home in the Berkshires with some shade and some sun. In actuality it is a clearing in the woods. Can I grow camellias there? If so, where is a good place to get those plants. Do I have to start from seed? They'd look beautiful!

    Thanks, Judith

    How 'bout I trade you some advice for a weekend at your place in the Berkshires? It's my spiritual home away from home.

    Re: camellias. I suspect the area's too cold for them outdoors; however, take a look at the hardiest varieties sold by the Camellia Forest Nursery. Most of those cultivars have names that start with "Winter". The best place to attempt a Camellia in your area would be a Western Exposure under the protection of a tall overstory of trees. Chances are you've got plenty of them.

    Best, KL

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    Blue Spruce With The Blues

    Dear Doyenne,
    I have several Colorado blue spruce with increasing needle loss at the base branches, mostly near the trunk but now spreading outward. I have noticed some doves roosting at night -- could this be the problem or something else? Also, I have a Japanese yew tree as a hedge close to my home that needs to be trimmed way back. How much and when can I cut it back to keep stress to a minimum?

    Bill in Springfield, MO

    Sounds like the lower limbs of your spruces are shading themselves out. This is a natural occurence on a spruce with some age, and is more likely to happen if the tree isn't getting absolutely, unimpeded full sun. My suggestion would be to limb up the spruce, i.e., prune them off. As for the yew, best time to prune it in your area is in early spring. You can remove quite a bit, so do so with confidence.

    Best, KL

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    Wimpy Wisteria

    Dear Doyenne,
    Several years ago I decided that I had to have a wisteria because everywhere around me here in central Texas were vines drooping with wonderful purple clusters of blossoms. I bought a plant, and at the time, the nursery man remarked that the ones he had that year were particularly well-developed for one gallon wisteria plants. Well, that was about 10 years ago. Each year the plant, now with a trunk of about 4 inches, buds out, but with leaves, lots of leaves, not blossoms. Last year I cut it back brutally and did get one rather wimpy cluster. I was hoping that this was the start of something, but this year I'm back to only leaves. Is there anything I can do, or did I just get a "lemon?" If you can help me make a bloomer out of it, I will be forever grateful.

    Sincerely, Charlotte

    Dear Charlotte,
    Life's too short to wait a decade for a vine to flower; my suggestion is that you rip that sucker out, take a trip to your local nursery (preferably a different one!), and buy a 5 gallon plant in FULL bloom. It's always a safer bet.

    Hey, I'm just the messenger. KL

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    Dry Shade

    Dear Doyenne,
    What do you recommend for dry shade? I have a corner where I've tried everything to amend the soil , but, as in real estate, location, location, location is the issue here. I've been putting pots there, but I desperately want something permanent! We're in zone 5.5 (but I'd brave a zone 6 denizen!)

    Thank you! Maureen

    Dry shade is a challenge but it can be done. Some suggestions for you: Arum italicum 'Pictum' (which I recommend for Z5, but not here in Z8, where it's an aggressive pest); Lamium maculatum, which comes in lots of flavors, all of which would work well; Vinca, not very romantic, but then neither is dry shade; Houttuynia cordata 'Chameleon', with variegated leaves in red, cream and dark green; Pachysandra, though you'll need 3 yrs for it to establish; Liriope (typically Z6, but worth a shot in a protected place; be sure to try the variegated form); and Cyclamen hederifolium which takes awful conditions, blooms well in late summer and has pretty mottled leaves (again, Z6 but go for it).

    Enjoy, KL

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    Hibiscus in Peril

    Dear Doyenne,
    I live just a few miles south of you in Albany, Oregon, so you know that the climate is relatively mild and moist. I have a Hibiscis. It is my favorite plant. It was given to me by a friend, five years ago, in a 6" pot. I placed it in my bedroom window and it has grown to be about 4' high and 5' wide!!! (Needless to say, it now occupies a MUCH larger pot.) In the last couple of years it has been plagued by whiteflies; they feed on its leaves, causing it to emit a sticky substance which now covers the shelf upon which the Hibiscis sits. The only thing my local nursery can suggest is regular sprayings of Permithrin or Pyrethrum. Needless to say, I'm not happy about spraying poisons in the house (or anywhere else, for that matter). Isn't there some organic or natural substance I can apply to my baby's leaves to either eradicate the whiteflies or make the leaves unpalatable to them?? Failing that, can you suggest a course of experimentation that would not prove inimical to my Hibiscis' health? If you can suggest a remedy, you'll have the undying gratitude of a beautiful plant and its friend.

    Regards, Byron

    Ugh, whiteflies. Unfortunately, hibiscus are very prone to them. One way to control them is to use yellow sticky traps; the flies are attracted to the color yellow. You can also lower their populations by hand picking (honest), and removing leaves on which they've laid their eggs. Hibiscus are less prone to whiteflies outdoors, so you should definitely move it outside (I suspect you're safely past frost, but don't quote me). The extra sunshine won't hurt the plant either.

    Hang in there, you two. KL

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