“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.

Canna Lily

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!

Helleborus orientalis hybrid early April

Hellebores, with their neat mounds of evergreen foliage and showy flowers in early spring are hard to beat as plants to cheer up shady spots under trees or on the north side of a house. They are members of the Ranunculaceae family and are generally native to southern and eastern Europe. Clumps of handsome leaves about 12 inches high produce many stems of nodding flowers early in the year. These are rather similar in shape to a cupped wild rose, but close inspection shows that what appears to be petals are in fact sepals. As is often the case where sepals are the showy part of the plant, this has the advantage of giving a prolonged blooming season with the “flowers” staying in good shape for several weeks. The mainly green or white colors of the wild plants have been improved by hybridization and now include a vast array of pinks, slate gray, maroon, spotted and picoteed, but they generally revert to green as they age. Double flowered varieties have also been introduced. Although they are poisonous to humans and animals they all have productive nectaries and are beloved by bees which will visit in large numbers on warm days.

Unlike most shade-loving plants, hellebores prefer a slightly alkaline soil in order to thrive. They do require regular irrigation and a mulch of leaf mold to help retain moisture is beneficial although large clumps can tolerate occasional drying out. The clumps are tightly formed, so they do not invade their surroundings but they resent disturbance once established so a mature plant will often take a couple of years to recover if it is moved (that is, presuming it survives). Likewise it is almost impossible to split a mature clump successfully. However, they frequently seed in large numbers around the parent plant, and it is a simple matter to dig up and transplant the seedlings, but of course the hybrids will not be the same as the parent in color or form.

Hellebores are not touched by deer or rodents, and are renowned for being pest-free; however, in my garden H. orienalis has had a quite serious aphid infestation in just the past two years, perhaps due to the mild winters.

Helleborus orientalis and its hybrids (sometimes described as H.x hybridus) need some winter chill and comfortably grow in Zones 6 and up. They have the widest selection of colors and are probably the most commonly grown and, therefore, most likely to be found in local nurseries. This species is often called the “Lenten rose” (although, of course it is not related to roses) and in my Bishop garden it generally produces a generous crop of 2 inch, white, cupped flowers between March and April. It happily grows as a large clump of dark green leaves on the north side of the house which is mostly in the shade, but between the equinoxes it does get a blast of afternoon sun which sometimes burns the leaves.

Helleborus niger or "Christmas rose" is winter hardy to zone 4 and is lower growing and produces glistening white flowers with yellow stamens in mid-winter. Variety 'Potter's Wheel' has larger flowers than the species and is much sought after, but it is hard to propagate. There are also pink and double flowered varieties. This must have alkaline soil, be protected from strong direct sun, and have a reliably moist soil.

Helleborus argutifolius or Corsican Hellebore grows in Zones 6-9, has coarse, blue-green toothed foliage and clusters of green nodding 2” flowers held on 2ft-3ft long stalks which have a tendency to sprawl. It can become almost shrub-like. Although more sun tolerant, it is not as hardy as the previous two species but has grown under heavy shade on a west-facing wall in Bishop for 6 years without mishap.

Helleborus foetidus or the Stinking Hellebore, is often grown more for its foliage than its flowers. Clusters of small, bright green flowers on long stems arise from clumps of handsome, evergreen foliage. Newer hybrids have been bred to produce interesting foliage such as finely divided leaves or bronze coloring. The plant is hardy to Zone 5, although the flowers will be damaged in those temperatures.

To see a sample of the huge variety of flowers available check out some of the specialist nurseries such as:

• http://www.thimblefarms.com/hellebore.html
• http://www.plantdelights.com/Hellebores/Helleborus-for-sale/buy-Lenten-Rose/Hellebore-plants/?view_all

The hour of the Dahlia

August and September are when dahlia plants are at peak performance. It is also when heat encourages spider mites to attack. The damage looks as though the plants are drying out at the bottom. If you look under the infected leaves, they will feel sticky and you will find black specks.

The best practice for controlling mites is removing the infected leaves at the bottom of the plant and washing the plants with a strong spray of the hose. Using an insecticide can make the problem worse by killing the beneficial insects that feed on the mites. If you catch it in time the plant will continue to produce beautiful flowers for you, they just won't have any leaves on the lower part of the plant.

Preserving Dahlia Blooms

Cactus dahlia.

Bring them in the house and set them in 2-3 inches of very hot water. Use either a plastic or metal container that doesn't retain heat. I use an automatic hot water pot and get the water to boiling before filling the plastic/metal container.

Leave the blooms in this water until it has cooled and then transfer them to your vase. You can cut the discolored ends of the stems off or leave them on, it doesn't matter.  This method of preserving blooms works on any woody stemmed flower.

I recommend that you change your vase water daily. You may also use a homemade flower preservative of 2 tablespoons sugar and 2 tablespoons vinegar along with a 1/4 teaspoon of bleach to a gallon of water.

Digging

Dig up your dahlia tuber about two weeks after a killing frost or November 15th, whichever comes first. Do not dig too early. Cut the stalks down to 6”. Gently lift with a spade being careful not to break the tuber necks. Wash off the tubers and let them dry, protected from the elements, for 24 hours. Ensure that they don't dry too much - our climate dries quickly.

If you have an area in your yard that will protect your tubers from winter frost you may try leaving your tubers in the ground over the winter. An area that is up against a southwest facing structure which will hold heat from the winter sun would be such a spot. For healthier, more productive plants be prepared to dig, divide and give these a winter rest every 2-3 years. You will have to experiment with this.

Storage

I'm still experimenting with this, so here is what the experts at Swan Island Dahlias say:

Use a storage medium such as slightly dampened peat moss, sand, or pet bedding material (sawdust/shavings). Tubers should be stored in crates or cardboard boxes line your boxes with 10 - 12 sheets of newspaper. Start your packing medium in the bottom and alternate layers of tubers and medium until the container is full. Never store your tubers in plastic or completely sealed containers. Store them in a cool, dry area. Ideal temperature of the storage location is 40-50 degrees. If the tubers are kept too warm they will wrinkle and shrivel, too cold they will freeze and rot. Check on your tubers thought the winter months.

During one August vacation my husband and youngest son happened upon the Swan Island Dahlia farm in Canby, Oregon (dahlias.com). “WOW!!” I was hooked.

I have now been growing dahlias for many years. There have been more successes some years that others, and I share my experiences below. Dahlias can be temperamental, so be patient until you find what works for you.

Location:  Dahlias like warm sun, not hot shade and they don't tolerate frost. They are best located in a situation that gets morning sun, but is protected some from the hot afternoon rays. Since they bloom late in the summer, the sooner you can get them started the better. They will wait for the soil to warm up before starting growth which can be hastened by planting in raised beds that warm quickly.

Preparation:  Dahlias like acid soil so I add 1 cup of sulfur per 100 square feet when preparing the ground. My dahlias performed best on the southwest side of the house in raised beds with good drainage.

Planting:  The tender tubers need to be planted well down in a 10-12 inch deep hole. Incorporate 2 tablespoons of bone meal into the bottom of the hole. Place the tuber on its side and drive in a sturdy stake next to it. By placing the stake now it serves as a marker, and also avoids the risk of damaging the roots or growing shoots which can happen once the hole is filled. I used 5ft 1inch redwood stake for my larger varieties. Cover the tuber initially with 4” of soil. Watch for sprouting and gradually fill in the hole as the plant grows.

Timing:  Because you plant your tuber underground, and you build soil around the new growth as it comes up, you can start your dahlias early. Spring planting is always a gamble in the high Desert. We have recorded frosts as late as June 8th. Getting a head start in the spring gives you more rewards from your plants. Be prepared to protect your dahlias from a sudden frost - Walls of water, frost cloths, etc.

I started my tubers on April 5, 2014 and had my fist flower on June 1st. Choose an early blooming variety if possible. I have had late varieties that never bloomed before the first frost in the fall! If your plant does get hit with a frost, it won't kill it, but it will have to start over.

You can also start your tubers indoors. When I tried this last year, I had more success with the tubers started outdoors. Although I can see where this might be a good option during a big winter and cold spring (If we ever get one of those again.)

Water:  Dahlias love water but usually the tubers don't need water until they sprout. In our climate (high desert) a light watering is often necessary until the plants emerge. When established you will want to give your plants a through deep watering about three times a week. I recommend a system that can deliver water to each individual plant so you don't waste the precious resource. Hand watering is not recommended because you won't get the necessary deep soaking needed. I have mine on a drip system which runs three times a week with a 1GPH emitter for 20 minutes. I supplemented that with a hose bubbler and flooded the beds every other week.

Fertilizer:  Use a fertilizer with a lot of Phosphorus for the blooms (this is the middle number of an NPK fertilizer.) A good choice is the same one you would use for your tomato plants. Follow the package directions. Fertilize after the first 3 weeks and then once a month until September. Stop fertilizing in September to promote a healthier tuber for winterizing.

Pests:  Slugs and snails love dahlias, especially little tender baby ones. Once you've filled in your planting hole, apply snail control around the top of your hole before the plant emerges to discourage them. Continue to apply throughout the season if the snails persist.

Later in the season as things warm up, watch for mites. If the lower leaves of your plant dry out and look like they need water, but you've been watering, you may have mites. Rinse the lower part of your plant to discourage mites. If you catch it early you may be able to wash them off, and remove the affected leaves. Mites won't kill the plant right away and you'll still get flowers on top. Normal fall frost is the first of October, so take all that into account before you resort to chemicals. Pesticides kill. Nature needs all of its checks and balances. For integrated pest management see http://www.ipm.ucdavis.edu/PMG/GARDEN/FLOWERS/dahlia.html .

Pruning:  This is the hardest part. As the stem emerges from the ground, the main stalk develops two branches on either side. After three of these branching pairs form on the stalk you have to pinch out the center. This encourages lower branching of the plant and will give you a stronger plant and more blooms on top!

Staking:  Staking is a must. Dahlias have hollow stems which often have to support very large (totally awesome) flowers that fall over easily, especially in our windy conditions.

Using the stake you placed at planting, every once in a while check and wrap a piece of garden twine around the entire plant with the stake in the middle, it will hold the plant up (unless you guessed wrong and your plant got too big, just add a second taller stake on the other side.) You don't need to tie up each individual stalk.

Harvest:  Sometimes this is a hard part - you might think that if you cut the flowers the plants will finish sooner, but the more you cut the more you get. One Fall I had several blooms on a couple of plants and thought we might get a frost so I cut them all off thinking that they were going to die anyway. Turns out we had a late frost that year and I was loaded with blooms after that! So now I feel guilty if I let a bloom expire on a plant without anyone enjoying it.

Cut your flowers in the cool of the morning, or evening before they are at the end of the bloom cycle. Not all dahlias are suitable for cutting, but I choose varieties that have long stems so I don't have to cut off the immature blooms in the same bunch. Have a pail of water handy to put them in as you harvest.

In the late summer, if your plants have a lot of buds, but don't seem to be blooming, they need more water.

Set the Bloom:  Some growers feel setting the bloom extends the life of the cut flowers. One way to set the blooms is to get several small containers of plastic, or metal (not glass, it holds heat.) Put 2-4 inches of hot (160-180 degrees F) in the bottom of the container. I use an electric hot water pot. I've also used the microwave, but don't use the container you use in the microwave to put your blooms in; it will be too hot since it is usually glass. Put the blooms in the cool containers with the couple inches of hot water with plenty of room for the steam to escape without affecting your flowers. Let the water cool for an hour or so, then transfer them to your vase.

Floral preservative will further extend the life of your cut flowers, although I just give my arrangements fresh water every day. The internet has many homemade preservative recipes, or you can buy commercial preservative.

A simple homemade preservative:

• 1gallon water
• 2 Tablespoons Sugar
• 2 Tablespoons Vinegar
• 1/2 Teaspoon Bleach

This is a good recipe to have, although I just give my arrangements fresh water every day. I'd like to do an experiment testing preservative vs daily fresh water or a combination to see what works best. But keeping it simple works best for me.

A subsequent article will cover lifting and storing the tubers at the end of the season.