The procession of spring flowering continues to unfold and is heading toward a glorious crescendo! It has been so exciting to witness the constant shifting of focus in the garden from one species or group of plants to the next. Hellebore, Daphne, Creeping Phlox, Golden Currant, and fruit trees, along with Crocus, Tulip, Narcissus, and other early bulbs give way to the first Penstemons, Basket-of-Gold, Catmint, Filigree Daisy, Sunrose, Evening Primrose, Blue Flax, hardy Geranium, and the dance goes on through the season! (Pictured left, Eve’s garden the week of May 24.)
Have you noticed that your daffodils and narcissus have been struggling and lost their vigor? Here are several possible reasons why and ways to address reviving them.
As with perennials, many flowering bulbs do best with fertilizing when planted, as their leaves emerge, and as they bloom, with a slow-release organic fertilizer such as Root Rally, from Age Old.
These are native plants that we often have for sale. Availability does change every year, but we grow and buy a wide variety of natives because they are so successful in our gardens.
KEY: t = tree, s = shrub, v = vine, gr = grass, gc = ground cover, p = perennial,
b = biennial, a = annual
Abronia fragrans (Sand Verbena) (p)
Acer glabrum (Rocky Mt. Maple) (t)
Acer grandidentatum (Bigtooth Maple) (t)
Achillea lanulosa (Native White Yarrow) (p)
Agastache cana (Hummingbird Mint) (p)
Agave parryi (Hardy Century Plant) (s)
Achillea lanulosa (Achillea millefolium var. lanulosa) (Yarrow)
Agave havardii (Havard’s Century Plant)
Agave parryi neomexicana (New Mexico Century Plant)
Amelanchier alnifolia (Serviceberry)
Amorpha canescens (Leadplant)
Amorpha fruticosa (False Indigo)
What a storm we had last week! With the windy conditions and record-setting low temps, everyone’s gardens looks very different this week and may need some attention. If you haven’t already, this is a good time to review our blog about garden cleanup. The good news is that soil temperatures have cooled down to the optimal soil temperature for bulb planting, ~50 degrees. And, our current mild daytime temps and above-freezing nighttime temps are ideal for planting perennials, and still good for planting roses, shrubs and trees. Inoculating with mycorrhizae and attention to fall and winter watering are the keys to success.
Starting with bulb planting: Recommended planting depths are to the bottom of the planting hole where the base of the bulb rests. Planting depth can vary depending on how light or heavy your soil is – plant deeper in light soils, shallower in heavier soils. (If you’re in doubt, a general rule is that planting depth is 3 times the height of the bulb.)
You don’t have to dig a single hole for each bulb! You can dig a large hole, say 8-14″ wide by 16-24″ long, to accommodate a large grouping, or swath of bulbs. This is a great way to save time, to create a more naturalized look, and to combine two or three types of bulbs in one grouping.
Single Early, Triumph, Darwin Hybrid, and Multi-flowering tulips should be planted 8″ deep to perform as perennials, and fertilized each year just after bloom. Be sure to allow the leaves and stems to wither naturally before cutting them down.
You may want to sprinkle bone meal in the bottom of the hole so that it can touch the bulb roots. We love Root Rally, which is a blend of bone meal and Endo/Ecto mycorrhizae spores and plant nutrients, providing mycorrhizae life support for all plants. (See more on mycorrhizae, below.) Refill the hole and water well.
Planting perennials, roses, shrubs and trees: The fall is a great time to plant perennials, roses and shrubs as they can focus solely on root growth instead of trying to reproduce. After gently removing its pot, gently swish the root ball in a bucket of unchlorinated water with water-soluble mycorrhizae (let the water sit overnight to release chlorine and add the mycorrhizae later). Mycorrhizae is a beneficial fungi that attaches to roots, allowing them to better absorb water and nutrients. This results in faster plant and root growth, and better transplanting success. If you only have granular mycorrhizae on-hand, sprinkle it on the roots as you are planting. Read more about mycorrhizae in Mikl’s article, “Mycorrhizae: The Hidden Marriage of Plants and Fungi”.
By gently swishing the root ball in water, the root mass will loose its pot-shape and individual roots will be lengthened. This allows the ends of the roots to be planted deeper, helping to ensure long-term drought hardiness.
After late-season planting, be sure to (hand) water deeply and frequently, at least twice a month for woody plants, throughout the winter.
For specific info on rose planting, see Eve’s rose planting instructions.
Finally, a quick additional word on garden clean-up. Some of our Southwestern plants should not yet be cut-back. Wait until April to do so, which will give them additional time to gather and store nutrients, and keep the crowns of the plants from getting too cold. These plants include, but aren’t limited to, Agastache, Salvia (S. lemmonii ‘Desert Rose’, S. reptans, S. x microphyllus ‘Royal Ruby’, S. greggii ‘Furman’s Red’, S. darcyi), Zauschneria (Hummingbird Trumpet), Scrophularia macrantha (Red Birds in a Tree), Scutellaria suffrutescens (Cherry Skullcap), Gaura lindheimeri.
Plant Select is a 25 year old cooperative program combining the efforts of Denver Botanic Garden, Colorado State University and some members of the local green industry. Their intention is to chose, propagate and promote plants that are well-adapted to Colorado conditions, colorful and are either little known or underutilized. The 2011 choices are a particularly excellent group.
Below is a list of many of the varieties of Penstemons that we usually have for sale at Harlequin’s Gardens. Penstemons are in general very well adapted to xeriscape gardens in Colorado. Many of them are regional natives and there are several that are native in Boulder County. In general, they like full sun and good drainage, however many can be grown in our clay soils if they are not overwatered. Some are 3′ tall, some are ground covers. Many are blue or purple, some are orange or red and there are a few whites. It is good to sow their own seeds in the fall to create sustaining populations. Try them; they are beautiful and fun AND nearly all LIKE hot and dry conditions, once established.
Many gardeners think of Spring as the height of the ornamental gardening
season. Sure, so many of our best-known flowering plants – Tulip,
Crocus, Daffodil, Primrose, Peony, Lilac, Forsythia, Oriental Poppy,
Basket of Gold, Bearded Iris, are at their showiest in spring. But as we
pass to the other side of the Summer Solstice, a whole new palette of
blooms arises, including many Natives, lots of Prairie-dwellers and
Steppe plants, and hardy plants from South of the Border, bringing bold
color and attracting more and different beneficial insects and
pollinators to the garden. Here’s a list of many of those flowers to
Note: plants listed in bold are native to our region
Achillea filipendula ‘Moonshine’
Achillea millefolium ‘Cerise Queen’
Everybody seems to love columbines with their delicate, exquisite beauty, both elegant and elusive. The Rocky Mt. Columbine is the state flower of Colorado and yet we seldom, if ever, see front yards swaying with masses of their classic loveliness. What is the story or trick to growing these plants successfully in Colorado? Because of my own mixed success with columbines, I decided for this article, to add the experience of other gardeners to my personal views.
Flood recovery is not a problem most of us have had to deal with before so we can only try to solve the problems individually and make adjustments in the future.
The main problems seem to be:
1) Soil washed away-erosion
2) Soil dumped on top of plants, trees and existing soil
3) Plants washed away
4) Weed seeds deposited on the soil 5) manure and sewage and unknown contaminants deposited on the land
The best chance of having delphiniums that don’t blow over is to plant them on the east side of the house or garage where they get good early day sun and where they are protected from the west wind. Next is to put in varieties that are not so tall and top-heavy. Here are a few varieties that fit that bill.
There are many varieties of Dianthus that are successful here in Colorado. Since there are about 250 species and 30,000 registered names of Dianthus, this article is only going to cover a fraction of the subject. Most of the species dianthus come from the Mediterranean region, the Balkan Peninsula and Asia Minor. They grow mostly in sunny, dry, well-drained soils among rocks or with short grasses in meadows, and most are happy in a more alkaline environment. These are reasons why they are often well-adapted to our natural conditions. Many varieties are easy for us to grow, and they satisfy us in many ways because some 1) are very fragrant 2) are excellent cut flowers 3) are durable, evergreen ground covers 4) are good in borders, cottage gardens, rock gardens and xeriscape gardens.
Here’s a shrub that won’t grow over the living room windows, spread half-way across the driveway or send suckers up in the perennial border. It stays a compact 2’-3’ high and a little wider. It’s name comes from its spring leaf coloration which begins a russet or bronze-red mixed with yellow, changing to yellow-green and then green. The flowers are pinkish and bloom for a long time. Then again in the fall the spring leaf colors return to a golden copper-orange. This variety is very heat tolerant and has been successful in my xeriscape garden for 7-8 years. Occasional winter dieback has been slight and easily sheared off with hedge clippers. I also use the hedge clippers to remove the spent flowers after blooming.
In the last issue I mentioned that Dianthus in general like sunny and well-drained conditions, and that because they cross-pollinate freely, you can only be sure you are getting a named variety like ‘Pike’s Pink’ if it has been propagated by cuttings.It is also significant that the strong fragrance common to many of the Dianthus tribe is not only pleasing to us humans, it is very attracting to many butterflies.
Here are a few more varieties that do well in our area:
As gardeners mature, we begin to loosen our fixation on flowers and learn to see and appreciate other aspects of plants that can be equally beautiful and enjoyable. Besides foliage color and sculptural form, texture is one of the important aesthetic elements in a garden.
Fine-textured plants can move with the breezes, glow when backlit and express gentleness and a delicate grace which is appreciated here in the rugged west. At the same time, fine leaves can be an aid to drought and heat tolerance.
We gardeners are always looking for tough plants. And those of us who are pursuing the elusive “sustainable garden” are searching for Colorado-adapted plants that do well with little or no care. But that is not enough. A sustainable garden is one where there is a balanced ecosystem of plants that can change as conditions change, to favor first one species and then another, but no plant should take over the entire space. Those dominating plants are the ones I call real weeds: the garden bullies.
Hardy Geraniums are in general very serviceable and these four have been very useful and successful for me. They are tolerant of diverse and adverse conditions and are especially useful in dreaded dry shade.
In 1993 I sent a survey to 29 local horticulturists to get their suggestions on the best groundcovers for a demonstration project we were planning at Harlequin’s Gardens. I asked them to list 5-10 groundcovers that could be used to replace bluegrass in low traffic areas, that would need a quarter to a half the water of bluegrass, have few pests and diseases, would grow densely to limit weeds, would look good in most seasons and would not be invasive in gardens. The survey was typed on a typewriter and most of the replies were hand-written. People did drive cars back then. But that was a long time ago and I had a lot to learn.
Hardy Geraniums are one of most versatile an adaptable perennials for our area. Available in many colors and habits, they can be useful in sun and shade, moist and dry, as a single specimen, as companion plants and as ground covers. These are not to be confused with the Pelargoniums which are the house plant, container and bedding plant “geraniums” which are not hardy outdoor plants in Colorado. The name “geranium” is derived from a Greek word meaning little crane, hens the common name “cranesbill” which refers to the appearance of the seed heads. The majority of the species of geraniums are native to the northern and mountain regions of Eurasia and North and South America although some are found in South Africa, India, Indonesia etc. Most grow in grasslands, meadows, roadsides and open woodlands. Therefore the natural habitat for most hardy geraniums seems to be sunny and moist or part-shade and moist or dry.
Most of our native plains plants and shrubs including:
Desert Four O’Clock
Sulfur Flower (Eriogonums)
Lavenders are great xeriscape perennials for Colorado, which bloom in the heat and dry of July and August. They are native to the rocky hillsides of the Mediterranean region. Here as well, they like good drainage, full sun, our alkaline soil and dry, loamy humus. Lavenders are aromatic herbs with gray foliage, the leaves as well as the flowers being strongly fragrant.
Plants are one of the most successful life forms. In fact, we could say that they are the most successful life form, because plants are self-sufficient. They can live without eating other beings because they can make their own food. Only plants, phytoplankton, algae and cyanobacteria can synthesize food from sunlight, carbon dioxide, minerals and water.
At the same time, plants have a serious limitation: they are rooted to the earth, so they can’t run away from pests and they can’t pursue another plant in order to have sex. But are plants helpless. Oh, no. They have developed chemical warfare and chemical magnetism to protect themselves from predators and attract allies.
“You can join the fight to save the honeybees by planting a pollinator-supporting garden.” This is a recommendation made by a Penn. State Master Gardener program. Is this weird? Not at all. The European Parliament has approved creating bee “recovery zones” across the Continent. These recovery zones will provide bees with nectar and pollen in areas that are free from pesticides. Why is it a big deal that honeybee populations around the world are declining? One reason is that one third of the human diet comes from plants that are pollinated by honeybees. Another reason is that honeybees may be the “canary in the coal mine”; just the first to show that there is a problem that hasn’t yet surfaced in other pollinators and other beings.