What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

50+ Flowering Pollen/Nectar Plants For Bumblebees

Posted by Hugh on January 24th, 2017

Russian sage is a bumblebee favorite

Lots of insect activity on Buddleia

Here are three key points in planning your pollination garden. To attract U.S. native bumblebees:

First, add both early(*), mid-summer, and late(**) flowers in the mix for a three seasons long garden.

Second, mass together many of the same kinds of flowers, not just one or two plants, so that bees will spot them easier and to visit the planting frequently.

Lastly, keep pesticide applications away from areas where trees, shrubs, perennials, biennials, and annuals are blooming. In particular, do not use systemic pesticides containing Neonicotinoids which are reportedly toxic to bees.

Agastache (Agastache spp.)
Ageratum (Ageratum houstonianum)
Bachelor buttons (Centaurea)
Beebalm (Monarda spp.)
Betony (Stachys officinalis)
Black-eyed Susan (Rudbeckia spp.) **
Borage (Borago officinalis)
Buddleia (Buddleia spp.) **
Bugleweed (Ajuga reptans)
Calendulas (Calendula) *
Catmint (Nepeta x faassenii)
Clovers (Trifolium spp.)
Comfrey (Symphytum officinale)
Coneflowers (Echinacea spp.) **
Cosmos (Cosmos spp.) **
Crocus (Crocus spp.) *
Cranesbill (Geranium spp.)
Culvers root (Veronicastrum virginicum)
Curry plant (Helichrysum)
Forget-me-not (Myosotis) *
Foxglove (Digitalis purpurea)
Goldenrods (Solidago spp.) **
Giant thistle (Cirsium rivulare)
Hollyhock (Alcea)
Honeysuckle (Lonicera spp.)
Heath (Erica carnea) *
Heather (Calluna vulgarus) *
Lavender Lavandula angustifolia
Lenten roses (Helleborus spp.) *
Liatris (Liatris spicata)
Marigolds (Tagetes spp.)
Marjoram (Origanum vulgare)
Mints (Mentha spp.)
Mountain mint (Pycnanthemum virginianum)
Mullein (Verbascum)
Nasturium (Tropaeolum majus)
Ornamental onions and chives (Allium spp.)
Peruvian verbena (Verbena bonariensis)
Pincushion flower (Scabiosa)
Poppies (Papaver)
Primroses and cowslips (Primula spp.) *
Pussy willow (Salix)
Red Valerian (Centranthus rubra)
Rosemary (Rosmarinus officinalis)
Russian sage (Perovskia atriplicifolia)
Sage (Salvia officinalis)
Sea thrift (Armeria) *
Sedum (Sedum spectabile) **
Snapdragon (Antirrhinum) *
Sweet alyssum (Lobularia maritima)
Sweet William (Dianthus barbatus) *
Sunflowers (Helianthus spp.) **
Thistles (Echinops)
Thyme (Thymus spp.)
Toadflax (Linaria vulgaris)
Wallflower (Erysimum cheiri) *

Our Native Bumblebees In Trouble

Posted by Hugh on January 22nd, 2017

Bumblebee pollinating

Recently, the U.S. Fish and Wildlife Service recognized ten more animal species as Endangered Species, providing them protections under the Endangered Species Act of 1973. These 10 species include 7 species of bees. Endangered status will afford the rusty-patched bumblebee protection under federal law.

Bumblebees build their nests in the ground (and other places). Honeybees, however, who are not native to the U.S., build and live in their mostly above ground hive (nest) for many years. Populations of rusty-patched bumblebee were once widespread across the U.S. and Canada. Today, their greatest populations are found in the northeastern U.S. and Canada, and their numbers are spotty in several locales.

Bumble bees face many threats including loss of habitat, diseases, pesticide usage, and climate change. Unlike honeybees, which co-habitate in large colonies (>10,000 individuals) in perennial hives, bumble bees produce smaller annual populations (50-1,500 individuals). Due to their smaller annual population sizes, life cycle, and genetic makeup, they are a lot more susceptible to extinction.

Bumblebees typically nest underground, and overwinter in undisturbed ground – one that is not planted or mowed. Bumblebees frequently nest in compost piles, woodpiles, stone walls, or empty bird houses.

According to the Xerces Society, here are some things that gardeners can do to help bumblebees:

Plant long flowering plants that start blooming early and finish late. Provide bumblebees with pollen and nectar from late winter through early autumn.
Choose flowers of plant species native to your region that the bumblebees evolved alongside with. Plant species from around the world may be beneficial as well. Flowers should closely look like open pollinating species. Don’t plant varieties with double petals that make it hard for the bumblebee to access the pollen.
Purple, blue and yellow flowers attract bumblebees. Bees cannot see the color red.
Avoid using pesticides in your flower garden.
Learn and understand the natural habitat of bumblebees
Involve gardening friends and neighbors providing and conserving bee habitats.

For additional tips on conserving bumblebees, visit the Xerces Society website: http://www.xerces.org/bumblebees/

Comparing Western Red Cedar And ‘Green Giant’ Arborvitaes

Posted by Hugh on January 21st, 2017

20 year old Thuja plicata in east TN

Needle foliage of Western Arborvitae

Western red cedar or giant red cedar (Thuja plicata) is native to the Pacific Northwest. In the eastern U.S. it is called western arborvitae and landscapers typically do not plant it. Instead, they plant the hybrid cultivar ‘Green Giant’ arborvitae, a cross between western red cedar (T. plicata and Japanese arborvitae (T. standishii).

Western arborvitae is typically found in cool moist forest areas and bottomlands from southern Alaska along the Pacific coastline to northern California and from British Columbia to western Montana (USDA hardiness zones 5-7).

Western arborvitae is the largest tree in the cypress family, averaging 100 feet and more in height and long-lived from 400 to 1000 years in the Pacific Northwest. However, east of the Mississippi River, expect dimensions 50-60 feet high and 15-25 feet wide at its base. It features horizontal branching with sprays of scale-like dark green foliage which is aromatic when crushed. Flowers are inconspicuous and small, half-inch long light brown cones follow and mature in fall.

Cultivar ‘Green Giant’ grows even faster into a large 50 – 60 feet vertical specimen tree. It is widely planted as a tall privacy hedge or screen. Screen grows to 50-feet in height and spread of 15 to 20 feet at its base. Young ‘Green Giant’ transplants grow 2- 3 feet annually if planting is adequately fertilized and irrigated. Summer needles are bright green and retain its green color through the winter, far better than Japanese cedar (Cryptomeria japonica) and Leyland cypress (x Cupressocyparis leylandii).

Western arborvitae grows best in moist, humus-rich, well-drained soils in full sun to partial shade. It thrives where summers are moist and cool. One year old established plants exhibit good drought tolerance, more so with age.

Western arborvitae exhibits no serious disease or insect problems. Bagworms may become serious pests. Root rots may occur if soil drainage is poor.

Currently, Green Giant arborvitae is replacing Leyland cypress as landscape privacy screening. Leyland cypress has proven susceptible to 3 serious disease problems in the southeastern U.S. Low growing shrub forms of western arborvitae are also available.

Landscaping Plantings Around A Garden Railroad

Posted by Hugh on January 18th, 2017

Tiny 'Curly Top' False Cypress Trained As Small Evergreen Tree

Tiny ‘Curly Tops’ Sawara False Cypress Trained As Small Evergreen Tree

Mix of Dwarf Conifers and Japanese Maples

Garden railroad layouts are becoming more popular. A number of dwarf and compact growing plants play a major role in landscaping around the layout. Many miniature forms of taller varieties are available. Here are several great plant choices to add the your garden railroad:

Trees and Shrubs – offer scale or tall canopy to the landscape:

Dwarf Japanese maples (Acer palmatum) choose from tree and shrub forms

Dwarf Korean boxwoods (Buxus microphylla)

Dwarf hornbeams (Carpinus spp.)

Drawf hinoki cypresses (Chamaecyparis obtusa)

Sawara False cypresses (Chamaecyparis pisifera)

Dwarf or compact growing cotoneasters (Cotoneaster spp.)

Dwarf hollies (Ilex spp.)

Miniature forms of Alberta spruce (Picea glauca ‘Conica’)

Dwarf (Lepidote) rhododendrons (Rhododendron spp.)

Dwarf sweetbox (Sarcococca spp.)

Dwarf hemlocks (Tsuga spp.)

Dwarf little leaf elms (Ulmus parvifolia) such as cvs. ‘Jacqueline Hillier’ and ‘Lois Hole’

Ground covers (serve to prevent erosion and added greenery in lieu of lawn grasses):

Maidenhair fern (Adiantum spp.)

Bugleweed (Ajuga reptans)

Low growing sedges (Carex spp.)

Ivies (Hedera spp.)

Dwarf hostas (Hosta spp.)

Certain euphorbia shrubs and ground covers (Euphorbia spp.)

Selaginellas (related to ferns)

Irish moss (Sagina)

Sedums (Sedum spp.)

Maintenance to your garden railroad landscape: timely pruning is an important chore. Bi-annual pruning in summer and winter is essential, particularly after the bed has been established. Plants that make good bonsai candidates may be added to a garden railroad landscape. Examples include ginkgo, junipers, plum yews (Cephalotaxus) and yews (Taxus).

Also, you may select several colorful annuals to the planting mix. Choose low growing forms such as such as petunias, snapdragons, star zinnias, French type marigolds, dwarf dahlia varieties, impatiens, moss rose (Portulaca), and annual spiderworts (Tradescantia). Taller flowering types such as select salvia species, angelonias, cupheas, lantanas, and gomphrenas may require pruning back every 3-4 weeks to maintain landscape scale and to keep plants flowering.

Feed plants with weak solutions of water soluble fertilizers such as Miracle-Gro™, Jacks™, or Schultz™ Plant Food. Regulate frequency of watering as not to flood plants or overstimulate them.

Powdery Mildew Disease Resistant Cultivars

Posted by Hugh on January 15th, 2017

Powdery mildew on herbaceous peony

Powdery mildew on Garden Phlox

Gardeners have learned to associate certain plants with a troublesome disease(s). Powdery and downy mildews have become epidemic in many regions of the U.S. Best ways for managing mildew diseases are prevention, good cultural practices, and spraying.. First, avoid planting susceptible cultivars. Plant in the proper location and space plants far enough apart so they’re not touching. Surrounding vegetation should not block air movement through the garden.

Follow good cultural practices such as reducing or eliminating overhead irrigation practices. Fertilize to optimize plant health, but avoid over-fertilization with nitrogen as it stimulates young, succulent growth which can be more susceptible to infection.

Some moderately susceptible cultivars may require protection with fungicide sprays, particularly if environmental conditions are highly favorable for onset of mildew diseases. Dig up and eliminate susceptible cultivars of lilac, roses, crape myrtle, impatiens, zinnias or summer phloxes. Plant breeders continue to provide gardeners with better disease resistant cultivars. In recent years, notable examples of resistant plants include:

Crape myrtles – ‘Catawba’, ‘Hopi’, ‘Cherokee’
Crabapples – ‘Prairifire’, ‘Sugar Tyme’, lots others
Dogwood (Cornus florida)– ‘Cherokee Brave’, ‘Appalachian Joy’, ‘Appalachian Snow’, ‘Appalachian Mist’

Dogwood hybrids (C. florida x C. kousa) – ‘Stellar Pink’, ‘Stardust’, ‘Galaxy’, ‘Constellation’ , ‘Aurora’
Sycamore – ‘Columbia’, ‘Liberty’, Yarwood, Exclamation™
Summer phlox – ‘David’, ‘Robert Poore’, ‘Delta Snow’, ‘Speed Limit 45’
Lilac – ‘Bloomerang’, ‘Betsy Ross’, S. meyeri ‘Miss Kim’, S. pekinensis

Monardas (beebalm) – ‘Marshall’s Delight’, ‘Blaustrumph’, ‘Colrain Red’.

Rhododendrons – R. yakushimanum, R. macrophyllum, R. ‘Nova Zembla,’ R. ‘Palestrina’
Roses – Simplicity™ and Meidiland™ roses, Rosa rugosa varieties
Zinnias – Z. angustifolius ‘Profusion or Zahara series; Pulcino and African varieties

One final thought: if foliage infections break out on garden plants in very late summer or fall, spraying a preventative fungicide is generally not necessary or impractical. Instead, practice good garden sanitation, a thorough clean-up of infected leaves and stems. For infected annuals and perennials, gather up infected debris and discard. Do not add it to a compost pile, but throw it curbside for pickup or add to a burn pile, obtaining the proper burn permits.

Five Simple Pruning Tips For DIYers

Posted by Hugh on January 11th, 2017

March Rejuvenated viburnum 3 months after cutback

Small Dramm pruner perfect for small 1/4 inch pruning cuts

Gardeners are frequently scared about making pruning mistakes. There are lots of gardening books filled with lots of before and after photos. Let’s face facts…your yard tree or shrub does look like the ones pictured in the pruning book.

Here are my simple 5 steps for pruning:

Why and When to prune: You can prune a tree or shrub any day of the year. The best time is generally in late winter. Choose a comfortable weather day to work outdoors so you’re not in a hurry. Remove low growing branches in any month. Branches that are dead, broken, infested with scale insects, or diseased can also be sawed or lopped off anytime. If the job involves major pruning, e.g. 30% of branches removed, spring or summer pruning is best time.
Flowering shrubs or trees — when do they bloom? Spring flowering shrubs and trees are best pruned immediately after or within one month after flowering. Can’t wait?…then prune when you’re ready. Crabapples, ornamental cherries, redbuds, dogwoods, azaleas, lilacs, forsythias, and spireas bloom on old wood in spring. Summer flowering woody plants bloom on new wood. Examples include most (not all) hydrangeas, chaste trees (Vitex), crape myrtles, althea (Hibiscus), butterfly bush (Buddleia), and roses.
Make the big cuts first. Take your time! Observe the tree from several points to determine the best cuts. Making many small cuts is okay, but they’re a lot more time consuming. Small pruning cuts heal faster than bigger ones. Completely rejuvenated shrubs are cut back 6 – 12 inches above the ground. Applying pruning wound paint is not necessary.
Use sharp pruning tools — Don’t plan to do all work in 1 year. If the tree has been neglected for several years, it may take 3-4 years to bring back desired shape and health. To repeat, don’t remove more 30% of branches in any one year.
Large shade trees — hire a certified arborist who should be properly insured and licensed. Maples, oaks, lindens, elms, birches, and others should be pruned every 5 years. Tree topping should be avoided as this practice results in a tree potentially more hazardous.

Types of Garden Irrigation

Posted by Hugh on January 7th, 2017

Irrigation system

Tree irrigation

These days there are lots of choices in watering gardens, individual containers, and newly planted trees. Before setting your flowers or veggies, install drip lines or soaker hoses. These systems are the most efficient method of watering and put less hurt on your water bill.

Drip systems deliver water at ground level and do not wet the foliage, limit evaporation loss, and result in less foliar disease infections. Soaker hoses and simple drip systems are available at full-service garden centers. They save water because it doesn’t end up on sidewalks or driveways.

Drip irrigation, also called “trickle irrigation,” allows you to custom-design a watering system for flower, vegetable, small fruit beds, and containers. Water flows through flexible tubing and out of emitters. Spacing for emitters preset by the manufacturer or set by the gardener. Always inspect emitters as they may clog up or rabbits and other critters may bite into the water line. Install a filter or strainer at the faucet to catch all debris and dirt. Clean out the filters every few weeks.

Over a 12- 24 hour intervals, drip or soaker systems deliver a column of water to a depth of 12 inches or more into the soil. This is adequate for most plants from shallow rooted annuals to deep rooted trees.

Tree watering bag

What about oscillating or overhead sprinklers? They are best confined to your lawn and not your flower or vegetable garden. Sprinklers provide an even supply of water quickly, but have two drawbacks. A sprinkler usually wastes water, spilling on sidewalks and driveways. Plant foliage gets soaked, and this may result in mildew and leaf spot disease infections.

While you’re away, an automatic watering systems may be what you need. All you do is set a timer that is attached to the hose or faucet. Two types, mechanical and electrical timers, are sold. Just attach timer to a faucet and set it to turn water on and off. Electronic timers offers the added benefit of watering at different times and days of the week.

Shopping Tips When Purchasing Plants

Posted by Hugh on January 4th, 2017

Idea: Grouping Deer Resistant Plants for Sale

Wonderful Selection of Sedums for sale

Spring and fall are excellent planting times and buying opportunities. A trips to a garden center can be very costly unless you go prepared. Here are some practical tips to make those shopping trips more enjoyable and a lot less expensive.

Create your landscape plan first before buying plants. First, visit garden centers to pick up great landscaping ideas at garden centers. Next, prepare your shopping list.

Avoid impulse shopping. You’re likely to see (and want) blooming plant at the nursery that are not on your shopping list. Check to determine how well the plant(s) will perform in your climate and soil. How much water and light do they need? How far apart to plant?
Read the plant tag. Find the plant name, its mature height and spread, blooming period, light and water requirements. Don’t be in a hurry. If the tag does not contain all growing information, search online with your phone or tablet.
Is the plant healthy? Avoid buying sickly yellow or nutrient starved plants. Pots should also be weed free.
Select plants not full with flowers. A few flower buds are ok or buy a plant that hasn’t flowered yet. Some early flowering shrub such as forsythias, weigelas, azaleas, or lilacs may have already bloomed.
Plant size on sale. Save lots of money purchasing a smaller plant.
Purchase locally grown plants whenever possible. Plants have been acclimate to your region’s weather conditions.
Plant warranty – does the garden center offer one? Save your purchase receipts.
Certified nursery professionals- does the garden center employ them. These knowledgeable employees have received lengthy training taught by state university Extension and Research Specialists. Area master gardeners are also invaluable local resources on plant care.
Other place to buy plants. Specialty online nurseries may grow some native plants, ground covers, roses, dwarf conifers, etal. that you can’t buy locally. State and city arboretums and university botanical gardens, frequently offer seasonal plant sales. You may find hard-to-find plants for sale at reasonable prices.
Fertilizer sales tip in display of hydrangeas

Southern Gardeners Should Use The AHS Heat Zone Map

Posted by Hugh on January 1st, 2017

Balloon flower (Platycodon) rated AHS 8-1

AHS Heat Map

The AHS Heat Zone Map isn’t new. The American Horticultural Society developed it in 1960 and updated it in 1990. It has become an important reference for knowing both the cold and heat tolerances of garden plants. Many perennials in southern U.S. gardens struggle in the extreme heat and humidity.

The heat zone map developed by AHS is based on heat, rather than cold, to determine a plant’s ability to survive in a specific location. It uses summer temperatures to demonstrate a specific plant’s ability to survive or handle the stress of high summer temperatures.

The U.S. Heat Zone Map is divided 12 zones. Each is derived from the number of “heat days” or the number of days the temperatures at 86ºF or higher. Each zone is identified by the average number of heat days it experiences in a year.

Heat zones are expressed with the highest heat zones listed first, followed by the lowest. For example, the heat zone rating for balloon flower (Platycodon) is AHS Heat Zone 8-1. This illustrates that Platycodon can tolerate and survive the summer heat in zones 1 through 8 (or 8 through 1). Sweetgum (Liquidambar styraciflua) is rated USDA hardiness 6 to 9, and AHS heat 9 to 6. A plant is listed as having AHS Heat Zone: 9-5, the growing season may be too short or summer temperatures not high enough for plants to flower in zones 1 to 4.

Several environmental factors, such as water, light, daylength, oxygen, and air circulation and pollutants, can skew the accuracy of a particular heat zone. Amount of rainfall is the most critical; plants lacking water are more susceptible to injury from heat.

Some plants vary in the ability to withstand heat, not only from species to species but even among individual plants of the same species! Unusual seasons- fewer or more hot days than normal- will invariably affect results in your garden. Sometimes, individual plant cultivars may survive outside their designated heat zone.

The AHS Heat Zone Map is intended to supplement the USDA Hardiness Zone Map, permitting gardeners to select plants based on their ability to survive seasonal temperature extremes in their region. Unfortunately, many plant labels (tags) still do not list their heat tolerance.

Are Your Plants Deficient In Magnesium?

Posted by Hugh on December 28th, 2016

Mg Deficient Boston Fern

Pink Double Knockout in nutritional stress

Pink Double Knockout with slight nutritional stress

Magnesium (Mg) is the central element involved in chlorophyll synthesis, a crucial nutrient in photosynthesis, and in maintaining vibrant green leaves. Like calcium, magnesium is required by plants in large enough quantities. It is a “macro-nutrient”, as important as nitrogen (N), phosphorus (P), and potassium (K), the latter three adsorbed by plants in greater amounts.

Magnesium plays a key role in chlorophyll synthesis, in fruit and nut production, and is critical for seed germination. Magnesium helps strengthen cell walls and improves plant uptake of nitrogen, phosphorus, and sulfur. Plants such as tomatoes, peppers, and roses need high levels of magnesium for optimal growth. However, plants often do not show symptoms of magnesium deficiency until it becomes severe.

Deficiency symptoms appear first in the youngest foliage. Magnesium deficiency shows up on most leaves as interveinal yellowing (chlorosis). Dolomitic limestone, frequently applied to adjust soil pH, will also supply some magnesium. Many water-soluble fertilizers like Miracle-Gro® and Schultz® Plant Food contain magnesium.

Magnesium deficiency causes yellowing of leaf edges on older leaves, compared with the interveinal yellowing present when iron is deficient. Magnesium deficiency can result in complete defoliation. In certain plants, such as geraniums, magnesium deficiency also causes the leaves to curl slightly upward.

Magnesium sulfate (i.e. Epsom salts) is an inexpensive source of water-soluble magnesium. It may also be applied as a foliar spray and is taken up quickly. It is available in drug and grocery stores and is compatible with other water-soluble fertilizers. Generally, 1 oz. per 100 gal. of Epsom salts supplies about 7.5 ppm of magnesium.

Many home gardeners are sold on applying Epsom salts to peppers, tomatoes, roses and some foliage house plants like ferns and dwarf palms. Citrus crops in sandy Florida soils and house plant citrus also respond by darker greening of leaves.