- Author: Alison Collin
As those faithful harbingers of spring, the daffodils, hyacinths and tulips fade it is time to get deadheading. This is done in order to prevent the plant from wasting its energies producing seeds and to divert the food that the leaves continue to produce towards the bulb so as to enlarge and strengthen it for next year's flowers.
The spent flowers should be cut off just below the swelling seed pod as soon as possible after the flowers fade. Tulips and daffodils are obligingly easy since the flower heads snaps off quite readily. It is a rather tedious business but I discovered that it was a job that my small children seemed to enjoy doing (for pay) once they were old enough to do it safely, and this gave them an appreciation of how plants grow and engendered a certain amount of competition so the job got done very quickly!
Bulbs will not produce a second flush of bloom, but other plants that come later - annuals and perennials -will often rebloom more than once in a season if they are prevented from producing seed. After all, from nature's point of view flowers are produced purely for the purposes of reproduction of the species, so if seeds are not allowed to form the plant will continue to keep trying.
To know exactly where to cut off the dead flowers can be a bit of a challenge until one has some experience of different species:
- Petunias, pansies, California poppies etc – dead flowers are pinched off just below the flower head.
- Roses: Prune back to a five-leaflet leaf, making a slanting cut as you would for winter pruning. Carpet roses can be lightly sheared, cutting just below the spent clusters.
- Perennials e.g. dahlias, asters, delphiniums, dianthus. If the flower stem also has leaves or obvious buds, cut back to just above those since that is where further growth will start from. With these plants if just the flower head is removed it leaves an unsightly spiky stem, but by taking the stem down to the first set of leaves it looks more natural.
- Plants with flowers held on naked stems, such as daylilies are cut back to the base.
- Lilacs, viburnums and hydrangeas: These need to be cut just below the flower head, and should be done as soon as the flowers fade since the plant will rapidly be preparing the buds for next year.
Remember to take a container around with you to receive the dead flowers – there is not much point in cutting these off and then leaving them around on the ground where they could harbor disease!
Nothing detracts from the overall appearance of a flower bed more than dead or dying flowers. Often one is tempted to leave a cluster if there is just one floret with some color remaining, but it is much better to cut off that inflorescence and get a replacement growing.
- 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: 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
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:
- Author: Lori Plakos
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
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:
/h2>/h2>/h2>/h2>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.