Frost Protection Issues
Question from Mary:
‘Tis I, Mary Bull from Chalice Farm in Sebastopol of the long thread starting with “kiwi problems” left off a few weeks ago. Your book must have come via slow boat from China, but it has finally arrived! Can’t put it down! So much I want to discuss with you, and will, by and bye! This time, I will approach issues by subject for your blog.
Frost Protection
I have had to interrupt reading your wonderful tome–though I did read the sections on frost protection for citrus and avocados, geared mostly for your milder climates so near the coast– because of the arrival of the first Alaskan front of the season, bringing short interludes of below freezing temperatures over the past few days. We are eight miles from the ocean here, so have to deal with both extremes. We also had the audacity to plant citrus and avocados, which require some protection, at least during the first several years. I have gone the rounds with them, starting with burlap teepees when they were small, opening their south-facing side when weather permitted–a labor-intensive, not wholly effective measure. I then tried frost blankets picked up at a local home-improvement store–way too thin, and inadequate instructions (simply wrapping the tree in it does not suffice as I later found out). So last year I switched to heavy-duty frost blankets and talked at length with the manufacturer in Atlanta, Georgia, about the principle on which they work and how to use them (I will share with you that the principle is that they catch and hold heat emanating from the ground, so it is best if a lot of ground around the plant is exposed–i.e. no mulch or ground-cover–and then covered with the blanket, as well. The frost blankets are typically draped directly onto the plants foliage and secured with dirt, stones, or whatever around its base. However, I built makeshift frames from fence posts and bamboo poles for the blankets to protect the new growth on the plants (this growth is both tender and brittle on citrus, as you know), because despite my efforts to get these plants to harden off (stopped feeding at the end of JUNE, gradual reduction in water…), they always insist on having an enormous growth spurt in the fall. The gauge of frost blanket that I used was 8-degrees (warmer than outside temps) while allowing 50% of the light to penetrate (of course, air and rain also penetrates the spun poly cloth). Despite this effort, I lost 2/3 of my beautiful Bearss lime, the central leader from my Stewart avocado, and sundry new growth from others during a 5-day cold snap of 25 degrees last winter. After that, I resolved to construct larger mini greenhouses and drape them in clear plastic greenhouse 5–6 mil sheeting, which does not breathe, therefore keeps more of the hot air in: We bought an SUV-in-a-box from Shelter logic to cover the two biggest Bacon avocados, and tried a Shed-in-a-box for another; secured them to the ground, and then draped and clamped the plastic over these. We still need to add guy wires to secure them further against the 70 mph winds we occasionally get. We switched to constructing frames from rebar, which was far less expensive and looks a lot better. As you point out in your book, heat can be as much of a threat as cold, and must be attended to. My local cooperative extension agent said to leave a gap around the bottom and this would be adequate. The plan is to open the two short side of each mini-greenhouse during the day when it is sunny to allow for pollination, ventilation, etc.
We shall see. It’s my hope that once these trees mature–i.e., get enough girth/older growth in their trunks and branches, I can dispense with the frames and just throw cloths over them. I am not sure how long this will take. The oldest trees are four years. My Bacons are the most tolerant of all the chalenges (besides weather, they have to deal with more clay than they would like–the Mexicolas which pollinate the Bacons, especially hate the clay, but we have been conditioning the soil with compost and green manure for years, and started adding gypsum and humic acid after visiting your site and the UC Davis site, which recommends gypsum (as a source of Ph-neutral calcium, which kills the fungus) )and coarse mulch as an antidote for root rot. So, I hope they come around. Except for these, I make sure that everything else I plant is hardy to at least 10 degrees 😉
Any further comments or pointers, would be immensely appreciated, as ever!
Thank you for your wonderful book–photos are marvelous, too!
PS. I noticed you planted a gorgeous climber called Rosa America, and I have been wanting to plant a couple of climbers, so look forward to discussing them with you at some point.
PPS Also, the information you provide on watering is terrific, but some of it is contrary to recent publications (e.g., Roots Demystified), and I look forward to discussing those with you, too.
Many thanks, as ever!
Answer from Pat:
Thanks for this terrific email: Here are some quick comments: Your efforts re: Frost protection for tropical fruits in a borderline (or near-impossible) climate are noble to say the least! Down here, a clever idea for lighter-weight frost protection is to keep those old outdoor Christmas tree lights, now superseded by newer types. (I tell folks to try Goodwill or thrift shops for those old ones that give off heat.) String onto the trees and then cover with the new frost-protection fabric. There are several types, as you have already discovered, including All-Purpose Garden Fabric, but this is too light for your climate and you are right in the idea to build a sort of plastic greenhouse. Have you thought of trying frost-protection fans? Years ago large ones were used in Claremont, California, in the San Gabriel Valley, at the foot of Mount Baldy, where I went to Scripps College, a magical place surrounded by fragrant orange groves in the days of my youth. The climate was warm in summer, but far too cold in winter for oranges to survive without winter protection. Oranges grown under these conditions were simply delicious and we had fresh-squeezed juice every morning, as I still do today. But in those days (late nineteen-forties and early fifties) farmers used smudge pots, creating clouds of black smoke and smog in winter.
Every time I revise my book (every ten years) it gets longer and longer, but I must try to mention some of these ideas when I do the next revision. I am surprised that your Extension agent suggested a gap around the bottom of the mini-greenhouses you are trying out. I would think heat would still build up inside during the daytime and burn foliage. I think your side-vent idea is better. In Yorkshire England where I spent my childhood, my grandfather had greenhouses of glass with rock walls below and these had vents that the gardeners cranked open on sunny winter days. There was a fish tank in each greenhouse and it helped preserve heat and a sort of steamy atmosphere. In summer Viney, our head gardener, grew tomatoes and zinnias in the greenhouses, but most other veggies and all fruits were grown outdoors. When you cover a frame with heavy plastic you are in a sense building a greenhouse, but the plastic ones are called “range-houses” by flower growers and house-plant growers here. Books explaining proper management of greenhouses should be of help. One problem for homeowners is that most plastic sheeting degrades when exposed to sunlight.
What brand do you use?
I look forward to the other topics you plan to discuss later.
Loved your email, especially the magical memories of the smudge pots, orange groves, and fresh orange juice when you attended Scripps at the foot of Mt. Baldy! Truly enchanting! (Love those purple and lavender San Gabriel mountains!) That sent us on an Internet adventure re smudge pots–nice Wikipedia entry… which says that it’s actually the particulate matter from the smudge pot smoke that prevents the frost damage, not the heat, which is almost negligible. There are smudge pots still for sale, but they won’t work with the plastic tents.
The reason Paul Vossen, our Cooperative Extension guy, gave for the bottom vent being adequate is the coolness of our winters here (rarely above 60).
What do you think of Wilt Stop, a pine-based substance that coats leaves and protects them from the elements while not inhibiting growth? They recommended it at our local farm supply store, which caters to organic farmers and gardeners. Not OMRI certified, but they seemed to think it was basic and harmless, and that it helps plants cope with freezing temps. I tried it on two guinea pigs trees, and noticed that the insects that lighted on the leaves, left quickly… This may be ok for the citrus, which blooms primarily in spring and summer, but several of the avocados, and the strawberry guava, are blooming now, and I don’t want to inhibit pollination. It could be that the insects will not be repulsed once the substance has set and dried. I will check tomorrow. Let me know your thoughts and experience!
The Christmas lights I have heard about, but placing them tends to mangle the very thing I am trying to preserve 😉 Still, another tool in the box!
Typically, we have a very few short blasts of sub-freezing temps, which made me feel the citrus and avocados are do-able. I am still very optimistic!
More soon! Many thanks!
How exciting to find out that you have discovered WiltStop, a newer and (according to its inventor) far better kind of anti-transpirant than others invented earlier. If you look at my summer-veggie garden videos, (taped the year before last at my younger daughter’s home), you will note I sprayed it onto the large leaves of a mildewed squash plant. It instantly cured the problem and left a clean,shiny leaf and will do so on such plants as cucumbers, melons, pumpkins, and other plants prone to mildew. I recommend always planting a disease-resistant variety, but unfortunately the great majority of gardeners don’t know of these things. (Many varieties of cucumber, melon, pumpkin, and squash, are susceptible to mildew, but a few, heritage, open-pollinated varieties and the best hybrids are immune and should say so in the seed catalogues and sometimes on the seed-rack packages.) On the subject of mildew I should mention that I also used Serenadeâ„¢ on the leaves and it cleared up the mildew just as expeditiously and it is OMNI certified.
I have never thought of using an anti-transpirant as a protection against frost damage. Twenty years ago I learned from the then head Horticulturist at the San Diego Zoo that he was using anti-transpirants as barriers against pests, including snails and slugs. He was not allowed to use anything that would harm birds or other animals in the zoo so that sounds as if it’s perfectly safe. (It was a different kind than this pine-based variety of anti-transpirant and I think was made of plastic which does not sound harmless if animals ate it.) Of course, as you doubtless know, one of the earliest uses of anti-transpirants was as a spray to keep Christmas trees fresh and green longer by holding in the moisture.
I have not thought of the possibility that anti-transpirants might scare off bees. I tried years ago to spray an entire climbing rose with the stuff in the hopes of preventing mildew, rust, and pest damage. I think it would have worked but it was too time-consuming since I didn’t buy it by the gallon as does the San Diego Zoo. If one accidentally got it onto flowers and pollen this would definitely prevent pollination. But if one could protect the flowers by wrapping them some way then it would be fine. I am always warning people not to use Spinosad where bees visit because despite the OMNI label of approval, Spinosad kills bees. This is one of those cases of good-doers run amok.
The same goes for Sluggo Plus. The “Plus” means it contains Spinosad and thus kills sowbugs as well as snails and slugs, but what if honeybees come to drink water from wet ground where Sluggo Plus has been spread? Or what if native bees and beneficial mud-daubers gather mud where this product has been used? Then death to the bees or their “children” back in the hive and death to the wasps too. Some people might be happy about that but not me. Wasps kill scads of pests. Like you, I believe in the balance of nature.
When we had a few freezing winters twenty or thirty years ago, I always covered my foxtail agaves (Agave attenuata) with old sheets and pulled them off first thing in the morning. Same with cineraria. (Cinerarias love cold weather into the forties and thirties but melt if hit by frost.) If you have only a few freezing nights, blankets and such would definitely work to protect trees against frost but you would always have to be home to spread them and you would need enormous blankets. Your individual greenhouse idea is much better, covered with UV-resistant plastic. I can intuit how much fun it is just dreaming this up and trying to win out against the climate, as you are trying to do.
Have you ever thought of growing lemons and limes and other citrus in large pots and then making an Orangerie, as in the eighteenth century in France? —Think Marie Antoinette, Versailles and Le Notre. It’s still done there today on great estates and not just in France but also in Italy. The pots are brought out again in spring and make elegant garden decor.
Mildew and Peach Leaf Curl
Thank you so much for relating your positive experience with WiltStop! We had serious mildew and peach leaf curl problems the past two years–even the resistant varieties were getting the fungus!–due to late spring rains (as late as the end of June). We treated both with Serenade: Just this year, the manufacturers discovered that when used at twice the concentration, Serenade kills the peach-leaf curl fungus: THIS WORKED LIKE A CHARM on two of our three non-resistant varieties (Harkins and Lorings) and also the Late Santa Rosa plums (which are very susceptible to PLC), but did not work at all on the O.Henrys. Oddly, despite many applications, the Serenade was not effective on the wine and table grapes that got mildew, except the ruby reds which I caught earlier on…not sure why. Will try the WiltStop on the grapes this spring, perhaps.
We were prepared this winter after they go dormant to try our hand at Bordeaux mix (lime, copper sulfate, and water) on the O.Henry’s and possibly some of the worse-hit grapes. However, Stella Otto warns in her Backyard Berry Book that not all table grapes can withstand Bordeaux mix. Also, mixing it is a challenge. In your book, you recommend Bonide (same people who manufacture WiltStop) Organic Lime Sulfur Spray, which I intend to get and try, before I resort to Bordeaux mix. I am not sure which creates more collateral damage/side effects, the Serenade or the lime sulfur spray–copper in the soil is an issue with the latter, and perhaps the Serenade eats good fungus as well as bad–any thoughts?
Frost Protection
Yes, I love the potted, sculpted, poodle-tail citrus in formal gardens like Versailles! I made a movie when I was a film student at AFI called “Courtyard” in which the main setting was just such a garden with potted orange trees, fountain, koi pond, and so on! Still one has to have a lot of greenhouse space to overwinter the potted plants, or the covering and uncovering of them becomes too time-consuming and labor-intensive a task, wouldn’t you say? ! I like the formal structures we have built out of rebar, which rusts beautifully and actually looks attractive in the gardens when the plastic is off, so can be left up year round. I want to replace the SUV-in-a-box (you can imagine!) with such structures. And Chalice Farm is a bit more rustic than Versailles–or your exquisite flower gardens!
I think I will refrain from using the WiltStop on the flowering avocados–their flowers are so tiny and profuse, it would be difficult to isolate and cover them when applying the WiltStop (but it might work with light weight paper towels). My four-year-old Bacon has at least four dozen fruits on it at varying degrees of maturity (harvest is December)–my gut feel is not to apply the WS on it, though I would love to stop the grasshoppers from eating its leaves! However, I will go ahead and use WS on all the citrus (even though the Meyer lemon was flowering throughout October, and may still be!). I think I got the Stewart avocado before the buds opened. Before spraying the citrus with it, I will give them their dose of micro-minerals, including iron… I suspect that the foliar mineral spray will not penetrate the WiltStop.
All for now, Pat Dear!
Many thanks!
I am afraid if we overuse Serenade it will stop working since new resistant strains of harmful fungus might occur. I suggest using fixed copper and oil against peach leaf curl and spraying more than once in winter. I have stopped recommending Volk Oil since it is a poisonous petroleum product but I still recommend horticultural oils to smother pests. Sounds as if you already read what I said in my book about organic gardeners and using dormant spray in winter. Even organic gardeners need to use dormant spray several times in winter. (repeat at least once a month, more if rain happens soon after application.) Scraping off loose bark first and paying special attention to cracks helps. Spray up close, not like a blanket. It does not make you a non-organic gardener to use dormant spray. Rake and clean up the ground and renew mulch with fresh, but we should try to keep spray off the ground, just as you said, when using copper-based sprays.
We used to be able to get Bordeaux spray, now no longer, not sure why or what is going on with regulations. My stepfather always mixed his own on our farm.
You are a more devoted gardener than my current strength enables me to be. I no longer have the massive flower gardens, but instead have planted many succulents and I love the way they look, especially now as the rains have begun. A few years ago I planted Korean grass (Zoysia tenuifolia), small rock-garden type achilleas, and succulents on the island bed where I once grew poppies, wildflowers, and occasionally in summer, zinnias or melons. It looks lovely. As I age I keep simplifying and making everything easy care and drought-resistant. Nonetheless, the garden is still attractive and atmospheric. I fear I may lose a mature Senegal date palm (Phoenix reclinata) to a newly imported and horrendous tropical pest of palms, the red palm weevil (Rhynchophorus ferrugineus). There is no known cure.
Poor Pat! I am so sorry for you and your beloved date palm! How terribly sad! Prayer–San Ysidro, and beyond, for intervention there! I love date palms–so majestic and just simply gorgeous!!! It’s wonderful that you have grown them! May they overcome!!! …On a happier note, I love succulents too–they can be so beautiful, and I am right behind you when it comes to seeking homeostasis in low maintenance and optimum beauty! I just want to hobble into my redwood forest when I am 97 and bask in their radiance. Getting there is the challenge! Thank you for your dormant spray suggestions; I will use them. I only discovered Serenade this past season, so I personally have not overused, but I hear you. Much empathy, Dear Pat! –Mary
auge of frost blanket that I used was 8-degrees (warmer than outside temps) while allowing 50% of the light to penetrate (of course, air and rain also penetrates the spun poly cloth). Despite this effort, I lost 2/3 of my beautiful Bearss lime, the central leader from my Stewart avocado, and sundry new growth from others during a 5-day cold snap of 25 degrees last winter. After that, I resolved to construct larger mini greenhouses and drape them in clear plastic greenhouse 5–6 mil sheeting, which does not breathe, therefore keeps more of the hot air in: We bought an SUV-in-a-box from Shelter logic to cover the two biggest Bacon avocados, and tried a Shed-in-a-box for another; secured them to the ground, and then draped and clamped the plastic over these. We still need to add guy wires to secure them further against the 70 mph winds we occasionally get. We switched to constructing frames from rebar, which was far less expensive and looks a lot better. As you point out in your book, heat can be as much of a threat as cold, and must be attended to. My local cooperative extension agent said to leave a gap around the bottom and this would be adequate. The plan is to open the two short side of each mini-greenhouse during the day when it is sunny to allow for pollination, ventilation, etc.
Thank you so much for your sympathy. I phoned the Department of Agriculture today and reported my find of one red palm weevil and the fact that fronds look scraped, but my palm might still be okay since the green fronds emerging from the tops of the seven trunks still look healthy. The weevil, which I found under a yellow and red table cloth just prior to my departure on vacation, might have been a single one alighting in my garden after a stricken palm across the street was cut down.
Okay, having just returned from New Mexico—Albuquerque, Santa Fe, and Taos—and 3 days painting in Sedona en route home, I have now become acquainted with San Ysidro. (Having previously been friends with St. Fiacre and having a handsome terra-cotta statue of him in my garden.) So I will consult with San Ysidro. God knows I need all the help I can get and seems as if San Ysidro had enormous success in that department while not being all that responsible himself. But on the other hand, I am of the opinion that we have to bend with the wind and not kick and scream too much. Hence, I am already thinking of replacements, if one is necessary, such as a sub-tropical flowering tree that can take ocean breezes. Tipuanu tipu, for example—I already have a beautiful Markhamia hildebrandii. I am also planning how I might manage to remove and preserve a magnificent moosehorn fern (Platycerium superbum) that I have grown on one of the trunks of this majestic, multi-trunked palm. (See video http://www.youtube.com/watch?v=iTaNSjK2es0
. Thanks to the banana peels, it’s twice as big now as it was one and a half years ago when my web-partner, Loren Nelson, taped that video.)
I really enjoyed your email–it made me laugh outright several times.
Glad to hear that the date palm may not be infected after all!!! Regarding your replacement in the sad case that it is, I have loved jacarandas since childhood, when I lived in South Pasadena on a block lined with them. The tipuana tipu is also known as the yellow jacaranda (though the former is more lovely to the ear)–indeed, it looks just like them, substituting yellow blossoms for the lavender.
Besides the tipuana tipu, your email sent me on an Internet search for St. Fiachra which was very rewarding. Have you seen pictures of the garden that Ireland opened at the Millenium called St. Fiachra’s Garden in Kildare? It’s wonderful, with what appears to be an Andy Goldsworthy giant, dry-stacked stone bee hive as one of the landscape features (I love his work!). Too bad St. Fiachra hated women–maybe we can win him back over (maybe you already have)!
WE LOVE NEW MEXICO! And this is indeed where I discovered San Ysidro. My sister and first cousin (like a second sister to us) have both lived there (ABQ, Santa Fe, and Medanales) for the past 12–15 years or so, so we have had occasion to visit fairly frequently in all seasons. There is no place on earth like it for natural beauty or awesome spiritual sites, and the incredible Pueblo Indian cultures! We always go overnight by train (the Southwest Chief out of L.A.), which is an adventure in itself! Two years ago Thanksgiving we put in an entire irrigation system at my sister’s ranch in Medanales (a tiny town about a 45-minute drive NW of Santa Fe, and an hour south of Taos). I love their use of Russian Sage in Santa Fe, and attempted planting it at the farm, but it does not thrive here–the climate, no doubt.
A couple of things I had meant to mention:
I believe that WiltStop works against frost damage in the same way that smudge pots do: they insulate the leaf from freezing moisture with a layer of pine lacquer in the case of the former and soot with the latter. My greatest concern with the product is possible adverse impacts on insects and spiders. So far, I have seen none die outright, and saved a couple of Japanese beetles from drowning in in. I hate killing anything is the course of my gardening, and leave it to Nature to effect the balance, while I attempt to follow her lead with as much diversity and structural mimicry (e.g., modeling our food gardens after forests) as I can achieve within my personal limits…
I look forward to your video, once I figure out how to enable sound on this machine ( a nifty hand-me-down apple laptop from my tech-whiz brother in law).
PS Wonderful that you have children who are also into gardening!
Well, fie on St. Fiacre. Mother Nature would NOT be pleased. (Could this explain why he met an untimely end in his garden?)
Re: WiltStop, I don’t believe such products kill pests or beneficials. They only coat leaves so pests cannot chew through them. Spiders can freely walk across coated leaves, but will need to search elsewhere for pests.
Re: Jacaranda, I love this tree but it does not bloom well in cold wind, such as ocean wind, thus would probably not be worth growing in my garden.