Growing Concerns 494: Male-female differences in bushes

Late Fall!

Male-Female differences color the show of berries on shrubs in a hedge


Dear Janet,

I'm planning a hedgerow with plants that will attract birds. My question is whether all fruiting shrubs require male and female plants in order to set fruit. I know that certain plants do, such as northern bayberry ("Myrica pensylvanica") and holly ("Ilex verticillata"). But what about chokeberry ("Aronia arbutifolia"), spice bush ("Lindera benzoin"), American cranberry bush ("Viburnum trilobum"), fragrant sumac ("Rhus aromatica"), and Oregon grape holly ("Mahonia aquifolium")?


Dear S.L.,

Flowers have structures we've dubbed female and male -- a female pistil can produce fruit if it's fertilized with pollen from a male stamen. Many plants grow both pistils and stamens, so that even solitary individuals of that type can produce ripe berries. Many shrubs, including chokeberry, cranberry bush viburnum and grape holly are in this group.

Spice bush is different. Like true holly, it's dioecious -- a single plant produces either pistils or stamens but not both. In such species we call a plant that has pistils a female and understand it can't set fruit unless a stamen-producing male plant of that species is nearby.

Bayberry and fragrant sumac walk the line between the two groups. Usually they are dioecious, but sometimes one plant can berry on its own.

When a top-selling species has separate male and female plants and the buying public is interested in that shrub or tree for its fruit, growers identify plants by sex. Holly bushes are commonly tagged this way -- 'Blue Princess' and 'China Girl' are berry-bearing females meant to be paired with compatible pollen-producing males 'Blue Prince' and 'China Boy.'

It's not common to find male and female tags on less popular dioecious species. Although many garden centers sell bayberry and a fair number offer spicebush, only a few specialty nurseries might have spicebush in the male variety 'Green Gold' and female 'Rubra,' or female 'Myda' and male 'Myriman' bayberry.

To be sure to get fruit on spicebush, bayberry, and sumac, buy only when they are blooming so you can look closely at the flowers. You've found a male when the fresh flowers -- those that have recently opened and show no signs of fading -- are producing powdery pollen. If you do not find any pollen, chances are very good you've found a female. One male is all you need to pollinate a yard-full of females.


Dear Janet,

In November I put a bittersweet branch in water and am keeping it in the house by a south window. Will it take root and can I plant it outside next spring? I change the water every so often and add a bit of liquid fertilizer. I've also found the little seeds in the bittersweet and have tried to plant these but it doesn't look like anything is coming up.


Dear M.O.,

To grow bittersweet from a cutting, take a six- to twelve inch hardwood cutting while the vine is dormant between November and late March or a semi-hardwood cutting in midsummer.

Wrap and store hardwood cuttings like you would carrots, in a moist 40 degree crisper drawer or buried outdoors in sand. In March, re-cut the base of a hardwood cutting and "stick" it -- insert half its length into moist sandy potting mix. Then wait for it to leaf out, grow it in good light, water it carefully, keep the foliage from drying out and apply just a bit of dilute fertilizer. Roots will begin to form after a month or two.

Stick more cuttings than you need because some will fail to root.

Bittersweet is dioecious, having separate male and female plants. So if you want the bright orange berries, grow two. Take hardwood cuttings from a female -- one that had berries last fall. Then at blooming time in June, identify a male so you can take semi-hardwood cuttings from that one at midsummer. Stick semi-hardwood cuttings right away.

Although you looked for berries and flowers as identifiers, take cuttings from new branches that did not yet flower or fruit. These usually root best.

The seeds will sprout in spring if you clean away the fruit, plant them in moist potting mix, then set the planted pot or tray in a refrigerator or outdoors. The seeds require two to three months' chilling before germination time.


Short reports

Nightlights for poinsettias...

Paul Ecke, one of the leading names in U.S. poinsettia production, writes in "The Poinsettia Manual" that a poinsettia's show lasts longer if a small light is left burning near the plant at night.


Green thumbs

up to retailers who keep gardening tools out for the holiday shopping season. We gardeners love to give practical gifts and prefer the real thing to gift certificates. We're faithful to you all year when you cater to us during the mis-labeled "off" season!


Green thumbs down

to snowbirds' covetous ways. Stop dreaming about growing southern plants in northern landscapes. Those attractive trees and shrubs you see during your winters down South are almost certainly not hardy here or you would already be familiar with them.


Originally published 12/14/02