Do I leave my Siberian iris alone through the winter, then cut them back in the spring when new growth starts to show, as I’ve done in the past, or do I cut them back now? My neighbor has had hers cut back for months now and insists her way is best…
According to the book The Siberian Iris, by Currier McEwen, 1996, you should
“allow leaves to remain on the plants as long as they are green and adding energy to the plant through photosynthesis. When they turn brown in the fall, cut them off as low as possible and burn them.* It is risky to add them to the compost pile, as they may carry fungal spores, insect eggs, and other disease agents.
*Or put them in your trash (in a sealed bag).
When is the best time to divide and transplant Irises? I have Japanese, bearded and yellow flag (I think) irises.
Rhizomatous irises (the kinds you have) are best divided in midsummer:
Lift rhizomatous kinds, such as bearded iris, in midsummer and cut rhizomes into sections, each with roots and a fan of leaves; replant, with tops barely covered, 6 inches apart. Flowers will be sparse the next year, but good thereafter.
(Source: American Horticultural Society Plant Propagation, ed. by A. Toogood, 1999, p. 202)
“The optimum time..is six weeks after flowering. This is usually in midsummer, allowing time for the new rhizome to become established and make sufficient growth to produce fans to flower the following year. New roots that began growing immediately after flowering will then be strong enough to help anchor the new plants. Early spring is another suitable time, just as the other main period of root growth is about to start, but flowering may be forfeited, and if flowers are produced the stems will almost certainly need staking. Bearded iris cultivars are tough, and if the rhizome is large they can survive out of soil for many weeks. This is not an ideal situation, but it makes transport of the plants easy.”
(Source: The Gardener’s Guide to Growing Irises, by G. Stebbings, 1997, p. 93)
Good instructions can be found in these articles:
Digging, Dividing, and Replanting Bearded Irises
Garden Experiences: Dividing Bearded Iris
I bought a nice kit of paperwhites this year. Now, they are done blooming. The only directions about aftercare are: “After flowering, remove the dead flowers and stems, the leaves should continue to grow.” Is this plant ever able to flower again? Can they be planted in the garden, and if so, when? Should I not cut the yellow leaves off, like tulips, until they are all yellow, to promote bulb growth next year? Or should I simply throw them out, as they are not capable of re-blooming?
Most sources I consulted say it probably is not worthwhile trying to get your paperwhites (Narcissus) to rebloom. It can take several years for the bulbs to build up enough energy to rebloom. (If you still want to try this, do not cut off the wilted foliage, store the bulbs in a cool but not cold place, and try planting them out in the garden in spring. Paperwhites will naturalize outdoors in warmer climates–zone 9 or 10.)
When and how do I divide Tradescantia?
Divide in spring. “Cut away excess foliage, keep divisions moist and sheltered.” (Source: American Horticultural Society Plant Propagation, ed. by Alan Toogood, 1999, p. 148, 210).
What causes my chrysanthemums to do the big flop? One even came out of the ground! We have had a lot of rain lately, and it seems like a lot of plants did the big floppy, from roses to sedum, and now the mums. Is it all weather-related?
Yes, certainly the weather contributes to the big flop. Certain perennials just can’t stand up to heavy mist and rain.
Some gardeners stake their flop-prone plants before they flop over, while others dig them up and grow things that don’t flop.
You can prune perennials to help prevent flop. Typically you cut a perennial back by 1/3 a few months before it flowers. This causes the plant to branch out, producing a bushier, shorter, less floppy plant. In The Well-Tended Perennial Garden (Tracy DiSabato-Aust, 1998), the author suggests that staking be done early: …after the first flush of growth but before full growth. The stems need to be sturdy, and flower buds should not be formed yet…[stake] without adulterating the normal habit of the plants. Follow the natural line of the stem. (p.63)
My question is about Oplopanax horridus. I planted one last winter in deep shade. It has lost its leaves and appears to have gone dormant. 1) Does devil’s club go dormant in the winter? 2) If not, then could it come back with watering in the winter climate or am I better to rip it out and put in another one? 3) How frequently should devil’s club be watered in a normal summer and assuming good loam soil?
Devil’s club does lose its leaves in the winter. Quoting from the source cited below, it is hardy down to at least 5 degrees F, although the young growth is likely to be cut back by spring frosts…On cool moist soils, it forms tall, impenetrable thickets…Plant in sun or part-shade.
(Source: The New Royal Horticulture Society Dictionary of Gardening, Vol.3, 1992, p. 378)
Additionally, devil’s club “grows in well-drained to poorly drained soils with sandy, silty, or loamy textures,” which indicates that it will appreciate regular watering that ensures moist soil in the summer.
(Source: Propagation of Pacific Northwest Native Plants, R. Rose, et al, 1998, p. 129)
I have questions on general maintenance for the ferns in my garden. It is winter and the wood ferns (now about 4 feet in diameter) have fronds which are now partially brown. The deer ferns look similarly forlorn.
Should I prune all the old fronds off and let the new ones take over? How and when to do this without damaging emerging new growth?
Sources are divided on when and whether to prune wood ferns (Dryopteris). Some consider Dryopteris “self-cleaning,” meaning that the old fronds will eventually disintegrate on their own (Gardening with Woodland Plants by Karan Junker; Timber Press, 2007). If you are inclined to tidy up the look of your plants, they can be pruned of their old fronds after new growth begins in the spring (this can be risky: be careful not to cut the new fronds), or according to Pacific Northwest sources, in late February or early March before new growth starts. Rainyside Gardeners and Great Plant Picks, two Pacific Northwest resources, offer more information. Rainyside advocates pruning once there is new growth, and Great Plant Picks advocates pruning before new growth begins. The same is true for deer fern (Blechnum spicant, now renamed Struthiopteris spicant): “Old fronds should be cut back in late winter or early spring before new growth starts.”
This is a good general guide for pruning maintenance of ferns, written by Richie Steffen of the Hardy Fern Foundation. The first thing he points out is that cutting back ferns is purely an aesthetic choice; it is not necessary. If you do want to cut back, consider the type of fern: is it evergreen, winter-green, deciduous, or semi-evergreen? The answer to this question will determine the best practice.
Our Asters are green and getting ready to bloom but the
lower 8″ are “rusty” or burnt looking. Did our bark mulch hurt them? Too much
fertilizer? This is their third year in the same spot.
There are quite a few potential causes of the rusty leaves you are
seeing. It might be entirely normal, as mature Asters (renamed Symphyotrichum) can start looking a bit ragged in late summer. It could be due to excessive heat,
overwatering (symptoms include yellowing and dropping of lower leaves),
or fertilizer burn (Asters are sensitive to soluble salts in chemical
fertilizers). It could be a fungal disease, rust, or Aster yellows, a
common disease caused by a microscopic organism (phytoplasma) and spread
from plant to plant by leafhoppers. With Aster yellows, you would notice
a loss of green in the leaf veins, and yellowing of new leaves.
Sometimes, infected outer leaves turn a rusty or reddish purple color. A
good general practice to keep your Asters looking full and less leggy is
to cut them back by one-half to two-thirds when they have reached 12 to
16 inches in late spring/early summer. (Source: The Well-Tended Perennial
Garden by Tracy DiSabato-Aust, Timber Press, 1998).) Here are
links to resources which describe other possible causes of the leaf
problem.
Connecticut Agricultural Experiment Station
Missouri Botanical Garden
To determine the exact cause, it might be worth bringing a sample to a
Master Gardener Clinic.
My question has to do with the fall/winter foliage of bracken fern (Pteridium aquilinum). A friend trimmed the bracken to the ground. Will the bracken grow back next spring? This led to other questions. Does bracken lose only its leaves in the winter or does the entire plant die off? Does it spread through its roots or spores? Any information you have would be appreciated.
Bracken is deciduous, that is, the fronds die to the ground in winter and then regrow from the rhizomes in the spring. If your friend cut her bracken down to the ground late in the year there would be no problem. Even if it was earlier in the year, the bracken would probably survive. According to the fern books I read, people have tried mowing to remove their bracken with no success. The books also warn that bracken is very invasive and not recommended for small gardens. It spreads by underground rhizomes, maybe by spores as well, and can take over a large space in a very short time.
It might be a good idea to take a look at some pictures either in books or online (just enter the name in Google and select Images above the search box) to make sure this is what your friend has. Any deciduous fern (and even some evergreen ferns) can be cut to the ground in fall, but generally it is better to wait until the new fronds appear in spring to cut out the old fronds of evergreen ferns.
The USDA Plants Database provides further information.
Sources consulted:
The Plantfinder’s Guide to Garden Ferns (by Martin Rickard, 2000)
Ferns to Know and Grow (by F. Gordon Foster, 1984)
Can tall asters be sheared or lopped off early in the growing season to control height and make them bushier? I have Aster novae-angliae ‘Wild Romance’. I love the color and bloom-time, but would like them shorter.
Yes, asters (now renamed Symphyotrichum) can be pruned. This is sometimes referred to in England as “the Chelsea chop,” and it is a technique that may be used for a number of different perennials, as this article by Bunny Guinness in the Telegraph describes. An excerpt appears here:
“Plants now commonly manicured by their snip happy owners are Campanula lactiflora, sedums, rudbeckias, echinaceas, asters and heleniums. These have their shoots chopped back by around a third in late May/June. The basic rule is that perennials which only flower once should not be chopped or you will lose the flowers; varieties such as peonies, irises and aquilegias.”
Here is similar information previously available from the Colorado State University Cooperative Extension website:
“…control the height and shape of an aster by pruning. Gardeners can pinch asters like mums, regularly removing little bits of new growth until the first of July. However, an easier approach is to cut the aster back by one half in mid-June. At this time, the aster can be shaped. Outer stems can be cut lower than inner ones to produce a nice mounded plant. This shaping tends to encourage bloom near the base of the aster and discourage ugly brown stems. Although this pruning may sound extreme, it tends to delay flowering by only a few days and produces a much prettier plant.”