Fraxinus

( FRAX - in - us )

At-A-Glance Information

Commonly called Ash, this genus of deciduous and evergreen trees need full sun and are useful as lawn, shade, street, and patio trees. Most species tolerate hot summers and cool winters and varying degrees of soil quality and type. Flowers are followed by profuse clusters of winged fruit that can sometimes create litter problems under trees. Otherwise, these trees are welcome ornamental additions to gardens in many regions of the world. Take care when planting these trees in the landscape, as ingestion of plant parts have been found to have cause some toxicity symptoms in children and pets.

Fraxinus Species and Varietals

The genus Fraxinus is a member of the plant family Oleaceae and includes between 45 and 65 species.  The best growing zones for Fraxinus trees vary depending on the species. For more information, read the descriptions below. To find your zone, click here: Zone Map.

Fraxinus americana (White Ash)
​This deciduous tree grows well in zones 1-11 and 14-17 and is native to the eastern United States. It reaches 80 feet tall or more, and up to 50 feet wide. Leaves are dark green and turn purple in cooler fall temperatures. Hybrid variety 'Northern Treasure' is vigorous and disease resistant, reaching 40 feet tall and 30 feet wide. Leaves are glossy green and turn a pale orange-yellow color in fall.

Fraxinus angustifolia 'Raywood' (Fraxinus oxycarpa 'Raywood') (Raywood Ash, Claret Ash, Narrow Leaved Ash)
​This deciduous species grows well in zones 2b-9 and 12-24 and is native to the Mediterranean. Leaves are small, dark green and turn wine red in fall, and trees grow quickly to reach 45-60 feet tall and 30-40 feet wide. This species produces no seeds, needs moderate water, and is prone to branch dieback especially when stressed by drought conditions.

Fraxinus anomala (Single-Leaf Ash)
This species is native to the southwestern United States and northern Mexico, where it grows in scrub, desert, and chaparral landscapes. These are deciduous small trees or shrubs, and reach between 16 and 20 feet tall when mature. Flowers are brownish and 

Fraxinus dipetala (California Ash, Two-Petal Ash)
These plants are native to southwestern North America and northern Baja California. The species forms a deciduous shrub or small tree that reaches up to 23 feet tall when mature. Leaves are light to dark green and flowers are sweetly scented and white to greenish-white.

​Fraxinus 'Fan West'
Best in zones 2-14, this deciduous species of Ash is seedless; a hybrid between Fraxinus pennsylvanica and Fraxinus velutina 'Modesto'. Leaves are light orange green, and these trees reach about 50 feet tall and 30 feet wide. Tolerates cold, desert heat, and wind. Best with regular water but can tolerate some drought.

​Fraxinus ornus (Flowering Ash, Manna Ash)
Deciduous, this species is best in zones 3-9 and 14-27, and is native to southern Europe and Asia Minor. It reaches 40-50 feet tall quickly, and spreads to 20-30 feet. Densely foliaged that turns lavender and yellow in fall. In spring, fragrant and fluffy branching clusters emerge in white to green-white, and are followed by seed clusters. Needs moderate water. Variety 'Urban Bouquet' blooms heavily but does not set seed.
Fraxinus uhdei (Evergreen Ash, Shamel Ash)
This species is evergreen to semi-evergreen and grows well in zones 9 and 12-24. These Ashes are native to Mexico and love low-elevation desert landscapes. Grows quickly to 25-30 feet tall and 15 feet wide in about 10 years, and eventually reaches 70-80 feet tall and 60 feet wide. Leaves are glossy and dark green, and can burn in hot, windy climates. Will lose leaves in cooler climates. Best with regular water and occasional deep soakings. Commonly grown varieties are outlined below.
'Majestic Beauty'
Larger leaves and more reliably evergreen than the species.
'Sexton'
Compact tree with a rounded crown with larger, deeper green leaves than the species.
'Tomlinson'
Reaches 10-15 feet in 10 years, with a dense, upright habit and leathery, wavy leaves.
Fraxinus velutina (Arizona Ash)
This species of Ash does well in zones 3b-24 and is native to Mexico and the southwestern United States. It is cold hardy to -10 degrees Fahrenheit, and can also take hot and dry weather. Reaches 30-50 feet tall and 30-40 feet wide with an open form. Gray-green, velvety leaves turn bright yellow in autumn. Male and female flowers bloom on separate trees. This species needs regular water, and will attract birds to your garden. ​Southern California native Fraxinus velutina coriacea (Montebello Ash) is best in zones 8, 9, and 12-24. This subspecies has broader, more leathery leaves. Commonly grown varieties of Arizona Ash are pictured and described below.
'Berrinda'
Best in zones 3-24, this variety is tough and cold-hardy. This tree is native to New Mexico, and has an upright form to 35 feet tall and just as wide.
'Bonita'
Best in zones 8-24, this variety is great in the Southwestern United States and reaches 30-35 feet tall and is slightly more broad. Fall color is bright yellow and long-lasting.
'Modesto' (Modesto Ash)
Best in zones 3-24, this variety is native to Modesto, California and reaches 50 feet tall and 30 feet wide. It is a vigorous, fast grower with medium green foliage and bright yellow fall color. Resistant to Oak Root Fungus, but susceptible to many other diseases.
'Rio Grande' (Fan-Tex Ash)
Best in zones 8-24, this variety thrives in warm, dry climates and alkaline soils. It has large, dark green foliage that turns a golden-yellow hue in autumn. Resistant to windburn.

Caring for and pruning Fraxinus Trees

The first step in caring for a Fraxinus tree is to choose the right spot in the landscape for planting. These trees thrive in full sun, and should ideally be receiving at least 6 hours of direct sunlight each day. They can tolerate partial shade if necessary, but will not flower or produce foliage as well. Avoid placing Ash trees in areas that are prone to flooding or waterlogged soils for extended periods of time. These trees are adaptable to a wide variety of soil types, including loamy, clay, and sand. They will perform best in well-draining soils with a pH of between 6.0 and 7.5 (acidic to neutral). These trees are often found growing in riparian soils near bodies of water, but do not like to have their roots in standing water. After planting, apply a thick layer of mulch around the base of the tree to increase soil moisture retention, suppress weed growth, and regulate soil temperatures. Young trees should be watered regularly; this will help them to establish a deep, strong root system able to better withstand times of drought. Water deeply and thoroughly when the top inch of soil feels dry to the touch. Once established, these trees are considered to be fairly drought-tolerant, and can get by on precipitation during the cooler months of the year, but do need supplemental deep waterings in the warmer seasons.

These trees are not heavy feeders, and a simple application of organic compost each year in springtime should be sufficient to supply the necessary nutrients for the growing season. If trees seem to be struggling, they may benefit from a feeding with a slow-release balanced fertilizer applied in early springtime. Take care not to over-fertilize trees, as this can lead to excessive growth and a weaker tree that is susceptible to pests and diseases. Ash trees generally have a very handsome natural shape, but pruning can help to maintain an attractive habit by removing dead or damaged branches and improving air circulation. Prune during the dormant season, either in late winter or early springtime. Avoid pruning in late summer or fall, as this can stimulate trees to push out new growth that won't get a chance to harden off before cooler temperatures roll around, opening trees up to damage and disease. Canopies can be thinned from time to time to avoid developing fungal issues or powdery mildew.

Propagation

Fraxinus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your tree, follow the instructions below:

Propagating Fraxinus by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Fraxinus by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Keep in mind that in some species of Ash, there needs to be a male and female tree in close proximity to produce viable seeds. In some species, this is not the case; make sure to investigate the fertilization situation before attempting to grow from seed. Harvest your seeds. The seed pods are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Fraxinus seeds need a period of cold in order to germinate. After collecting seeds, place them in a sealable container or plastic bag filled with moistened peat moss or sand. Place the container in a refrigerator or freezer for 90 days, and then remove them.
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
The seed pods on Fraxinus trees are called Samaras, and produce ripened, winged seeds in fall.
There are between 25 and 30 seeds per seed pod.

Problems and Pests

Fraxinus trees are affected by the following pests and diseases:
  • Emerald Ash Borer
  • Ash Whitefly
  • Ash Anthracnose
  • Ash Dieback
  • Root Rot
  • Powdery Mildew
  • Wood Decay
  • Verticillium Wilt
  • Leaf Spot
  • Canker, Nectria Canker
For information on these issues, including how to deal with them if they pop up, visit the following pages:
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Gallery

These are wonderful landscape trees, and produce beautiful shows of white flowers each year.
Fraxinus greggii (Little Leaf Ash).
These trees make great additions to any landscape.
Fraxinus are wonderful in lawns.
These trees have foliage that stands out against darker backgrounds.
Mature trees have greyish-brown fissured bark.

Videos

Check out these amazing landscape trees.
How to identify Ash trees.
Check out this Ash Tree plant profile.
A great video about these landscape trees.

Resources

Care Guide for the Ash Bonsai Tree
Cutting Back Ash Trees - When and How to Prune Ash Trees
A Guide to Green Ash Trees
California Ash Tree Care and Maintenance Guide
Wikipedia: Fraxinus
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 327 - 328, Fraxinus (Ash)
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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