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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 I've already answered. Good clean fun for the whole family.

This week's questions:

  • Winter Worries In Florida
  • Pinion Nut Pine
  • Wind Chill Effect
  • Cutting Garden Under Eucs
  • Mexican Sunflower
  • Fickle Rosemary

    Winter Worries In Florida

    Dear Doyenne,

    I live in Winter Garden, Florida. It's just west of Orlando and just north of the Mouse with a capital M. I've lived here 20 years, and though it's not the coldest winter, it has stayed cold longer than any other winter. All of my hibiscus and "other bushes" are now burned a lovely shade of brown, and if the wind keeps blowing like it has been, will soon be leafless.

    My question is, when should I cut these plants back, and by how much? My hibiscus is (was?) about 10 feet tall. I also have some smaller hibiscus, but it's my big one that I'm most concerned about.

    Thanks so much!


    Since the winter's not over yet and more cold may be coming, the best thing to do right now is nothing. Wait until your shrubs start to send out new growth in the spring, and at that point, prune out the dead growth. Take the hibiscus back to its undamaged green stems; same for your other winter-burned shrubs. The good news is that the larger a plant is, the more resilient it is when zapped by cold. But admittedly, the jury's out on this one till spring.

    Best, KL

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    Pinion Nut Pine

    Dear Doyenne,
    I live in Southwest Washington. I tried to grow a Pinion Nut Pine in my yard. I have a southern exposure with lots of sun. I watered it with a solution of miracle grow and water. I babied it. It still died. I wondered if I watered it to much. Can you tell me how to get a Pinion Nut Pine to grow out here?



    I suspect you're talking about Pinus edulis, a 20'x15' shrubby evergreen native to the SW US. What a great choice. Pinion Nut Pine will do quite well in the NW with full sun and lean, well-drained soil and no, repeat no supplemental irrigation whatsoever. So try again and skip the babying; this one thrives on neglect.

    Best, KL

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    Wind Chill Effect

    Dear Doyenne,
    I live in Maryland, near Westminster. I have been told by seed catalogs that I am in Zone 7a.

    My basic question is, how do you factor in wind chills? Our low temperatures stay within the zone, but sometimes we have wind chill factors as low as 20 below. Because of this, should I consider myself to be in a more northern zone? Or, does the USDA or whoever makes these charts consider possible wind chills? Am I southern with regard to things like blueberries? Thank you. Barbara Cody

    Thanks in advance.


    Wind chill has little effect on deciduous plants, so if we're talking forsythia and blueberry, it's not an issue. Of course it does becomes an issue if the subject is broadleaf evergreens (boxwood, hollies, osmanthus, etc.) and to a lesser degree, needled evergreens. Sub-freezing winds rob leaves of moisture, a serious problem if a plant continues to photosynthesize through winter. But the USDA zones do not take wind chill into consideration, and if I were you, I wouldn't either. If you're not a risk taker, stick with Z6 plants; otherwise, let the cold winds blow. Re: blueberries, I can only guess, and would prefer you call one of your better local nurseries (or the Ag Extension agent) to find out what they recommend.

    Enjoy, KL

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    Cutting Garden Under Eucs

    Dear Doyenne,
    I live in Southern California, about 3 miles from the ocean, with light, sandy soil which resists water (I've never seen anything like it!). The most striking feature of my yard, however, are the GIANT Eucalyptus trees - originally planted in miles-long rows to act as a windbreak for the orange groves that used to be here. They drop a sticky residue, as well as lots of "acorns" which are wonderfully fragrant, albeit messy. The problem: nothing grows under these babies. I want flowers - preferably a cutting garden. What can I put in and have something beautiful in my vases?

    Thank you so much!


    Your best bet is to grow plants that are native to Australia because they're the most well-adapted to life under the Eucs. Of course, that does mean you're going to have to stretch your definition of a cutting garden, and think past zinnias and sunflowers. How about kangaroo paws (Anigozanthos), bottlebrush (in particular, Callistemon jeffersii), Boronia (B.megastigma, a plant you can find blooming at most nurseries right now), and emu bush (Eremophila). I hear that Roger's Gardens (in Corona del Mar) would be a good place for you to shop.

    Enjoy! KL

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    Mexican Sunflower

    Dear Doyenne,
    I live in Lancaster PA and for several years have enjoyed growing an annual plant with beautiful red-orange petaled flowers. It was given to me with the name "Mexican Sunflower," though I believe I saw it sold at a flower Market as "Dephinia torche" or somesuch name. I am interested in any info you can give me, but especially planting and storage advice for the seeds.


    The object of your affections is Tithonia rotundifolia , a member of the aster family. Store the seeds in a cool, dry place (an envelope will do), and wait until the ground is warm (late-May?) before planting in situ. The basic rule of thumb for seed planting is twice as deep as the seed is long, then cover with friable (read: light and loose) soil.

    Best, KL

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    Fickle Rosemary

    Dear Doyenne,
    I live in Bucks County, PA (clay soil) and have had no luck with growing rosemary. The bush I planted in the summer died, I think due to too much rain. I bought another in December and most of the inner leaves died; I think from under watering. The exterior leaves are now looking good, but it's barren on the interior. Can I cut it back to stimulate growth of inner leaves? I plan to plant it outside when the weather improves. When can it go outside and what else should I do for it to thrive?



    You would eat your heart out if you saw what rosemary does in the NW... but I won't gloat (much). Anyway, your inner leaves died from insufficient light -- rosemaries love to bake -- but I wouldn't suggest cutting it back (too stressful). It might be a good idea to wait longer than you'd think necessary before putting it outside, i.e., after the last frost date. Once outside, you need fast drainage and full sun. Why not mix some one-inch diameter gravel into your soil and plant the rosemary on top of that? If, by any chance, you have a south-facing wall, that would be the best. And in case you're looking for a tough-as-old-boots rosemary, try the selection 'Arp', which is fully hardy to -10F.

    Best, KL

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