- Author: Jan Rhoades
“You can't grow Canna Lilies here. They are tropical plants, not meant for our zone.” This was a recent statement made by a “dyed in the wool” British gardening friend. If you are an adventuresome gardener, like me, you recognize a challenge when you hear it.
When you go plant shopping at a nursery or garden center, most plants will have a tag that shows the United States Department of Agriculture (USDA) Hardiness Zone. Hardiness Zones were created in order to guide growers and provide gardeners with an easy way to determine which plants are most likely to thrive in any given location. The Zones are defined by the average annual minimum winter temperature. They are then subdivided into sections A and B, based on 5-degree F increments. If you visit the Agriculture Research Service (ARS) (http://planthardiness.ars.usda.gov/PHZMWeb/) web page, it is simple to enter your zip code and find your Zone.
Charlie Mazza, Senior Horticulture Extension Associate at Cornell University, put it best when he said, “In the real world, we garden in microclimates, not hardiness zones.”
A microclimate is the climate of a small area that is different from the area around it. It may be warmer or colder, wetter or drier, or more or less prone to frosts. These areas may be quite small – a protected courtyard next to a building, perhaps, – or it may be quite extensive, an area extending several miles inland from a large body of water, for example. In general, large bodies of water tend to moderate air temperatures of adjacent inland areas - low temperatures in winter are not as extreme, and these areas are less prone to late spring and early fall frosts. Smaller bodies of water, like a pond in your yard, have the same effect, just to a lesser extent.
Another example is urban areas which tend to have less extreme low temperatures that the surrounding countryside because buildings and paved surfaces absorb heat during the day, then radiate it back into the air at night. These buildings also offer protection from the wind.
Topography also has an effect on micro climates. Cold air flows downhill and collects in low spots so hilltops may not suffer as much from frost or cold temperatures. For example, here in Bishop, it is generally colder down at the airport by the Owens River that it is up at Apple Hill Ranch in Wilkerson. Of course, north facing slopes are slow to warm up because they receive less direct sun compared with south facing slopes.
Large scale micro climates dictate how our area is USDA Zoned. There is not much one can do about these effects except to be aware of them and let them guide plant selection and garden timing. However, you can look for smaller scale micro-climate effects at work in your yard and take advantage of them. Just like urban areas, your house absorbs heat during the day and radiates it back at night. It also offers shelter from prevailing winds and presents areas of shade and warmth. Fences, walls and large rocks can provide shelter and radiated heat. Raised beds, terraces and balconies can, like hillsides, offer a warmer, well drained space for growing. Paved surfaces, trees and soil types also offer opportunities and challenges, depending on what you might like to plant.
In addition to the USDA Hardiness Zone, other things that must be taken into consideration when choosing plants include its needs for light, moisture and care throughout the growth cycle. There are also environmental factors such as wind, pollution and localized microclimates.
Be aware of driveways, sidewalks, patios, and paved paths that can absorb heat during the day and re-radiate it at night, moderating night-time temperatures. If impervious, these areas can't absorb water, and may create wet spots if the water that flows off of them goes into one, concentrated area. The same can be applied where water flows out of downspouts and gutters or off of roofs.
Focus, also, on height, spread, and orientation of trees and current plantings. Tall trees can create excellent micro climates on your property by shading and protecting plantings, but they can also prevent rain from reaching the ground and provide too much sun protection in the summer, too little in the winter, especially if deciduous. Another consideration about trees: competition for water and nutrients created by the roots may make it problematic to grow less-competitive plants around the base.
Remember, no hardiness zone map can take the place of what you know and have observed in your own garden and yard. For instance, I made the mistake – some years ago – of planting a sapling cherry tree in what I thought was a fine place – and now I realize that it is in the shade of my large, old apricot tree, so it doesn't get much sun. By the same token, I have learned to plant my lettuce in the shade of other, taller vegetables so that I can have lettuce all summer, right along with my tomatoes!
While we cannot easily arrange and rearrange structures, hard surfaces, and trees on our property, we can incorporate a number of so-called season extenders to add productive days to the normal frost-free growth cycle for your Zone and create microclimates to our advantage:
- Raised beds and containers promote early growth, since they warm up sooner in the spring than the rest of the ground, especially if one edge of the bed or pot faces south. They can also provide optimal soil conditions.
- Use row covers. Woven polyester row covers have the advantage over clear plastic covers because they allow air circulation around the plants. Structures that surround plants...help store heat during the day and release it at night to protect plants from frost.
- Incorporate mulches to create desired micro climates by warming the soil (black plastic), cooling the soil (alfalfa and/or wheat straw), controlling weeds, and conserving moisture.
Let's say you want to have lettuce for your sandwiches and spinach for your salads outside of the “normal” growing season for these vegetables. You can tap into the benefits of creating microclimates in your vegetable garden to accomplish this goal. By utilizing south-facing raised beds in full sun you can get your seeds planted a week or two earlier in the late winter. By planting in containers you can move to a shaded area in the summer, you can extend the productive period for these cool season crops. And, by using winter-weight row covers in the fall, you can protect these tender plants from the falling temperatures...often extending well past the first frost.
Or, maybe you want to grow a canna lily in Zone 7b. Creating a micro-climate by planting in a pot and moving it to favorable locations according to the season is one solution. I chose to put mine in a sunny south facing corner by my house. The corner is protected from the wind and a warm toasty place in any season. I used mulch to keep the roots moist and covered the rhizomes with more mulch to make it through the winter. A raised bed might also be helpful in the future.
Gardening by using the concept of micro climates is, of course, a risk. We shall see what happens if the El Niño winter that is predicted comes to pass. All gardening, in the end, involves risk. And, the more I observe my garden, throughout the day and throughout the seasons, I can see where the microclimates exist, so that at least the risk is calculated!
- Author: Alison Collin
With the promise of El Niño bringing milder and damper winter conditions, this might be a good year to try growing some winter vegetables in the warmer parts of Inyo and Mono counties.
Choose your space. One of my problems is the fact that I tend to plant successions of vegetables all through the year, so I still have tomatoes, beets, parsnips, lettuce, peas, carrots and leeks taking up a lot of space! I also like to take the opportunity to leave most of the veggie plot fallow in order to cultivate it during the winter. Sometimes the areas that we choose for summer planting are not always the best ones to choose when growing in other seasons. Large open areas used in summer may well be subject to severe radiation frosts or drying winds in winter. Lower sun angles may mean that a spot that gets plenty of sun in summer might be too shady in winter due to a fence or other structure. Look around carefully to find a sheltered spot with the most light (especially if using frost-cloth tunnels which will reduce the light reaching the plants). However, those who live at high altitudes or in the colder parts of Inyo/Mono counties may be reduced to growing bean sprouts on the kitchen windowsill!
Be practical. With irrigation systems turned off, and relative humidity low, one can expect to be doing a lot of hand watering. Take the distance from a faucet into consideration. As the worst of winter recedes, and the sun gets higher, it can get very hot under tunnels of frost cloth, and in cold frames and greenhouses, so it will be important to open them up to allow air to circulate during the day, a tricky problem if one is not on the property full time.
Optimize what you have. If you have a greenhouse, this is the time of year when it can really pay dividends -one of our Master Gardeners picked ripe cherry tomatoes throughout last winter! However, if a greenhouse is not available frost cloth stretched over hoops of plastic or wire, or a hoop house, can still help modify soil temperatures to a greater or lesser degree. I make tunnels from 8' lengths of 3' or 4' wide field wire bent in half lengthwise with frost cloth stretched over and held in place with clothes pins - simple and effective. I find it easier to lift the whole tunnel off as a unit in order to tend the plants, rather than dealing with individual hoops. I have frost cloth, shade cloth and insect and bird netting cut to size so that I can cover the tunnel with what is most appropriate at any given time. High winds can shred plastic and blow mulch into the next county so make sure that covers are secure.
Other suggestions regarding cold protection: for individual plants a large upturned, hanging basket stuffed lightly with straw, dry leaves or even crumpled newspaper can help (I have even used a shower cap over the basket to keep the mulch dry during rain). The basket prevents the mulch from blowing away or getting scratched up by animals. For tender herbs growing against a wall, I use old window fly-screen panels with frost cloth cut to size and attached to the frame by clothes pins. I then lean the tops against the wall making a warm tunnel underneath. I have used old storm windows in similar fashion but found that they made the plants a little too hot. Sturdy tomato cages, no longer in use at that time of year can be placed over plants with frost cloth wrapped around the outside, and the top protected by a stout piece of cardboard attached by clips or wires.
Be vigilant about pest control: You may have found a nice cozy spot for your plants, but it is just as cozy for aphids, earwigs, sow bugs and caterpillars. I have seen cabbage white butterflies investigating my plants at the end of December! I also had to throw away several beautiful heads of broccoli one winter when they had the worst gray aphid infestation that I have ever seen. The infestation took hold during a cold spell when I had preferred to sit in front of a fire rather than caring for my plants – no amount of pressure hosing would remove the sticky mess!
Soil preparation and sowing techniques are much the same for winter crops as for any other time.
Plants should be mulched to reduce swings in soil temperature as much as possible, but of course this can only be done after seeds have germinated otherwise the tiny plants would risk getting smothered.
What to grow
- Lettuce, radish, onions and spinach, radishes, fava beans, beets and chard may be sown as seeds.
- Garlic cloves can be planted until early November.
- Well grown starts of the cabbage family: Brussels sprouts, broccoli, and small varieties of cabbage together with kale. Although these are hardy and tough plants they need to be checked regularly for pests.
- Parsley is tough and I have seen it flattened by a thick covering of ice from a leaking gutter, but a few hours later it was standing as if nothing had happened.
In the High Desert growing through the winter is always a risk and one's successes will vary from year to year but with good frost protection and possibly milder temperatures it might be worth a try, especially from Big Pine south.
Further reading:
- Author: Harold McDonald
When I moved to the wilds of West Chalfant a dozen years ago, I knew that native plants was the only way to go. Because there wasn't much available in local nurseries back then, I turned to the Internet and ordered a big box of plants online from Las Pilitas Nursery. Some have lived and some have died, but the true gem of that box has been a plant I previously did not know—Rhus ovata, commonly called sugarbush. As far as an all-around performer, it may be my very favorite bush.
Rhus ovata is native to chaparral below 4,000 feet, from southern California east to south central Arizona. Though evergreen in its native range, our colder winters can make sugar bush lose its leaves at the very end of the winter. Location can be key. The first few winters were pretty tough on my bushes, and I contemplated removing them. Instead, I cut them back to the ground and relocated them to areas next to the house. What a difference! They have thrived on the south and west sides of our house and generally retain their leaves throughout the year (though the leaves can brown along the margins around February).
As though its good looks weren't reason enough to grow it, sugarbush is incredibly low maintenance. Mine are now close to the house, so they get regular water, but they would do fine without it. On the Las Pilitas website, they say they haven't watered their mother plant in over 20 years! You can prune it however you like or even cut it back to the ground—it will only come back stronger, and unlike the deciduous Rhus species, sugar bush doesn't sucker profusely. The literature suggests wearing gloves when pruning, since, like other sumacs, the sap can cause a rash, but this is not something that has been a problem for me.
The problem, of course, is that I've never seen this plant locally, but look for it on your next trip to Southern California. Here are some native plant nurseries that carry Rhus ovata and a lot of other great plants.
- Theodore Payne Foundation, Sun Valley http://theodorepayne.org
- Tree of Life Nursery, San Juan Capistrano http://www.californianativeplants.com
- Rancho Santa Ana Botanical Garden, Claremont http://www.rsabg.org/grow-native-nursery
- Las Pilitas Nursery, Escondido http://www.laspilitas.com
Links provided for your convenience. No endorsement intended or implied.
- Author: Dustin Blakey
In case you hadn't noticed, our region is a bit different than most of California. For one thing we have this thing called "winter" to deal with. Although we may not get as much precipitation as we would like during the winter, we still have to deal with the effects of prolonged exposure to cold. In this way we are more like Missouri than California.
Recently I was asked about overwintering dahlias and gladiolus from the community garden. These are 2 plants that should not be left in the ground through the winter. In the case of gladiolus, in some winters many cultivars will survive but why risk losing your corms? (Corms are what gladiolus "bulbs" are really called.)
I was going to write a detailed post on overwintering glads and dahlias, but since I'm lazy, I checked to see if there wasn't something out there already written that would work. Fortunately Purdue's Cooperative Extension has a good fact sheet on keeping begonias, dahlias, geraniums, cannas and gladiolus through the winter.
Rather than reinvent the wheel, I'll just point you to this good resource. ⇒ https://www.hort.purdue.edu/ext/HO-085.pdf It mentions fungicides in the fact sheet. If you're in California, you should ignore those parts.
- Author: Alison Collin
On those wintry days when it is not tempting to work outside, and when one has already studied the contents of gardening catalogs, it is necessary to find other methods of sating the natural gardening urge. This is when I turn to bedside books, and videos depicting gardens around the world. While the content of many of these were not produced with “Science based education” in mind, I feel that they more than make up for this with design ideas and the sheer enjoyment of seeing accomplishments of fellow gardeners from other countries and areas. When reading or watching these I feel as though I belong to a rather select club as I can identify with the trials and frustrations of fellow gardeners and when they succeed, I can revel in their successes all from the comfort of my living-room.
There are a plethora of gardening books to choose from, but rather than choosing yet another “How To” book on the art of growing, I choose those with a more philosophical bent – those where the author mulls over a concept or thought that has occurred. Here are some of my favorites:
“The Bedside Book of the Garden” by Dr. D.G. Hessayon. This is definitely a “pick up and put down” book, packed with history, folklore, myths on all sorts of topics – famous plantsmen, carpet bedding, bats, how to skeletonize leaves, how to grow your own loofah – to name but a few. This book is my great escape, and once I have opened it I am lost to the world. It is delightfully illustrated throughout.
The Gardener's Bed-Book by Richardson Wright (1887- 1961) is another such book, written by the one-time editor in Chief of House and Garden. It does not have quite as much about gardens and plants at the above book, perhaps more of the philosophy surrounding those who garden, but it is quite amusing in places.
In the Eye of the Garden by Mirabel Osler. Although based in Britain, Ms Osler's writings are universal and this little book is described as “a book of the delight of sharing a true gardener's eye” with its elegant prose and black-and-white illustrations.
The Country Woman's Year by Rosemary Verey. This is a month-by-month chronicle of anecdotal observations on gardening and county living by one of the all-time classic garden writers. Rosemary Verey's garden in the UK is frequently open to the public and is very popular with those visiting from the US. This book is described as “offering an oasis of taste and tranquility”.
Gardener's Latin, a Lexicon by Bill Neal. It is surprising how many Latin terms you can pick up by browsing through this little book. It includes not only the meanings of various Latin names, but also their origins, and the lore surrounding them.
I have watched many DVD's on gardening, but again, rather than concentrating on the “How to Grow” type my main recreational watching is just for the pure enjoyment of seeing beautiful gardens and flowers. The following are some of my favorites. The titles are self- explanatory but a word of warning: Make sure that the DVD being offered is formatted for region 1 (north America and Canada), many are produced for Region 3 and won't play in the USA unless you have some very fancy equipment. This is especially important if purchasing used copies. If you are antiquated enough to still own a VHS player, tapes of these productions can often be purchased for little more than the cost of shipping. These are all honest to goodness gardening documentaries, with nothing of the “reality show” about them.
Gardens of the World with Audrey Hepburn. 8 episodes on 3 discs showing some of the most beautiful gardens from all over the globe.
The Great Gardens of England 6 discs featuring 58 different gardens from throughout all different regions of England featuring numerous different styles and designs. This is a really beautifully produced set likely to make those of us who try gardening in the desert green with envy (even if we cannot get our gardens to look green).
Australia's Rose Gardens Can be watched on Amazon Prime if you subscribe to that, but is not formatted to play on home devices in the US.
The Secret Gardens of England. 1 disc featuring 16 different gardens
Wisely Through the Seasons. Wisley is the Royal Horticultural Research Facility in England, where horticultural apprentices learn their craft, and where many plants are submitted for trials by hybridizers. It is an older DVD and shows many of the techniques, some quite fascinating, that they used in all aspects of horticulture as well as the beautiful gardens, the National Apple Collection containing hundreds of cultivars, greenhouses, how they assess new plants, the herbarium, and pathology department. I cannot find anything comparable that has been produced in this country, but those gardeners that I have loaned it to in this country have all enjoyed it.