Winter Review: Frost Heaving

Winter is the ideal dream time for cold-climate gardeners, but it’s also a perfect time to review good gardening practices and increase your gardening knowledge. For this Winter Review we’ll examine frost heaving.

Frost heaving can occur when winter weather brings wide temperature swings for days on end. Soil, originally frozen when cold temperatures settled in, will thaw. When the soil refreezes the ice that forms in the previously thawed layers expands. When this occurs at the base of some plants it can cause the crown and root systems to rise – or heave – from the soil, which exposes the roots to cold and drying temperatures.

If this happens multiple times, a plant can be pushed completely out of the soil. The result is a significantly stressed or dead plant.

Now factor in multiple frost/thaw cycles with heavy rainfall during an extended thaw cycle. Some of the rain settles into the top layers of soil making it even more likely to heave during a subsequent freeze.

The wide temperature swings we’ve experienced in Connecticut this winter, coupled by the lack of a constant heavy snow cover, has led to significant frost heaving. Shallow-rooted perennials – think strawberries, heuchera and scabiosa – are very susceptible to frost heaving, as are any plants in naturally moist soils and late-planted shrubs and perennials that did not have adequate after-planting time to extend their roots far into surrounding soil.

A heavy snow cover helps mitigate frost heaving. I noticed very little frost heaving after last winter, when three feet of snow blanketed my gardens and held soil temperatures constant throughout the winter. I’ve likewise found little frost heaving during winters that remain cold but have little snow cover.

If you’re a fan of frost heaving – which no right-minded gardener would be – this 2013-2014 winter weather has been ideal. We had cold temperatures and 3” to 5” snowfalls in early-mid December, but on the first day of winter outdoor temperatures were in the 50’s. By the first of January it was again cold, but all snow was long-gone until 5” fell on  January 3rd. That snow melted when heavy rains, along with a few days of temperatures in the 40’s and 50’s, followed.

January 15 brought frosty morning fog, quickly dissipated by the rising sun, and afternoon temperatures warm enough to entice this little caterpillar guy to wander.



OLYMPUS DIGITAL CAMERANow, on January 22nd, we’re back to a deep freeze – a low of about 5 degrees this morning – and 10” of new snow.

I hope this snow blanket remains – and is replenished – until spring begins to push this fickle Old Man Winter away. Though all my plants are well mulched, which offers some protection from frost heaving, I’ve already noticed heaving of one late-planted lavender and in the strawberry bed.

Sometimes there is nothing a gardener can do to prevent frost heaving, but a good blanket of snow until spring may help protect heaved plants from further damage – it may even save them from demise.

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Tend to Japanese Stilt Grass NOW!

Japanese stilt grass, an annual non-native plant that is invading many U.S. regions, is entering its final maturity stage in Connecticut landscapes. Tiny flowering units that will form the seeds for next year’s crop are emerging from each stalk. In Connecticut the time to tend to Japanese stilt grass is NOW!

OLYMPUS DIGITAL CAMERA As an annual, Japanese stilt grass (Microstegium vimineum) germinates, grows, flowers and seeds in a single growing season. Each tiny flowering unit will generally produce 100 new seeds. In three to five years Japanese stilt grass can completely overtake an area. The tiny stilt grass seeds easily spread in flowing water and strong winds, on passing creatures, and with any soil disturbance.

One key component in controlling Japanese stilt grass is preventing as many plants as possible from going to seed. Each of the 100 or so seeds produced by each plant can remain viable in the soil for seven years. This produces a Japanese stilt grass seed bank that can sprout to life in any disturbed soil for up to seven years after it is deposited.

In Connecticut, Japanese stilt grass generally germinates during late spring – late-May through mid-June. It flowers any time from mid-to late August through early September, and produces seeds from September through frost.

Because of its prolific spreading attributes, it’s easy to feel overwhelmed by a Japanese stilt grass. It will overtake your gardens, woodlands, and lawn if left unmanaged. Stilt grass management in home landscapes takes time and vigilance. It helps to know that each Japanese stilt grass plant that is prevented from going to seed will limit about 100 more plants over the next seven years.

Since my home landscape is in a Japanese stilt grass bull’s-eye zone, I’ve read as much as possible about it, observed how the plant grows along roadsides and on area properties, and asked experts for their management advice. Management requires a multi-pronged approach that depends on the size of the Japanese stilt grass stand and the area in which it is found.

Large stands of Japanese stilt grass, such as those along roadside edges, should be mowed while mature. In Connecticut that is now – early September – when plants are just forming flowering stalks but have yet to develop seeds. Remember: each Japanese stilt grass plant that is prevented from going to seed will limit about 100 more plants over the next seven years. Leave cut vegetation to dry in place since any raking or disturbance of the soil will encourage growth of stilt grass seeds laying in wait in the soil.

Smaller stilt grass infestations can be hand-pulled by spreading your fingers through the base of the plant and gently pulling upward.  With mature plants out, any smaller Japanese stilt grass plants are easier to see and pull. When pulling, try to get as many roots as possible without disturbing the soil too much.

Three years ago we first discovered maturing stilt grass growing among native grasses and ferns along a woodland edge of our property. We weed-whacked the area flat during late August, left all vegetation to dry through September, then piled about 6 inches of wood chips to cover the 6×8 foot area.

The following June, July, August and September I watched for and pulled every stilt grass seedling and plant from the mulched area.  But we also noticed maturing stilt grass in adjoining areas that must have come from previously unnoticed seeding plants. We weed whacked these areas in early September, before the stilt-grass produced seeds, and left cut vegetation to dry.

This year, 2013, is the third season of managing stilt grass in this area. Fewer plants sprouted this year than in previous years. During June and July, I was able to hand pull young stilt grass plants from the mulched area which is now nicely re-establishing with native ferns, grasses and wildflowers. In the areas without mulch (seen in the photo at the beginning of this post) we allowed this year’s stilt grass to grow through August and hand-pulled mature plants just yesterday.

Some close-ups of Japanese stilt grass show how the smaller plants, easily hidden among ferns and other native vegetation, will grow to become more visible.


The leaves of Japanese stilt grass often develop a white stripe along the central vein. Flowering parts emerge from the top of each stalk.

This photo shows a small portion of the wood-chip mulched area as well as the heavily infested area after we finished pulling Japanese stilt grass. Hiding amongst mature Japanese stilt grass plants were wildflowers, grasses, ferns and moss.


Japanese stilt grass will grow in sun or shade and in dry or moist soil. To keep it from establishing in the native woods around our cultivated landscape, I take a stilt grass management walk through these areas in June, July, August, September, and October. It seems most likely to first appear under trees and where soil has been disturbed, but it will grow most anywhere. I pull young plants and leave them to dry and die. Any plants found in late August or later – those that potentially have flowering stalks – go into a bucket for disposal into the trash.

Any stilt grass plants found growing in my perennial beds also go into the trash for disposal. To be safe, do not place Japanese stilt grass or any other invasive plant into compost.

Japanese stilt grass control in the lawn is a whole different topic. Because Japanese stilt grass is an annual, its entire existence centers around producing seeds. Therefore, Japanese stilt grass plants that are mowed regularly along with lawn grasses will flower and seed even when cut to lawn height.


Yes, those mini stilt grass plants – the wider leaves with the white stripe – will often produce seed even at this height.

We currently pull out any small, individual plants found growing in our lawn areas. Unfortunately, stilt grass has also invaded a 20×50 foot area of lawn grass on our property. Since the area is a bit large for hand pulling, my husband resorted to torching it. Using a propane-fueled torch, he burned the tops of the stilt-grass – and all other grass. Since stilt grass is an annual, the torched plants should not regrow. We hope the perennial lawn grasses will regrow, and we are currently watching the area to see if they will. If not, we will overseed to re-establish a good thick lawn which will should help minimize future germination of new stilt grass plants from seeds still in the soil.  Watch for a future post to see how this experiment works.

Controlling Japanese stilt grass has become a critical part of our landscape management plan. If it is growing on or near your property, you’ll have to adopt similar measures to prevent it from overtaking your landscape.

Remember: Each Japanese stilt grass plant that is prevented from going to seed will limit about 100 more plants over the next seven years.

Read UConn’s advice for good background information on Japanese stilt grass.

The Invasive Plant Atlas of New England has more information and color photos of Japanese stilt grass.

Go Botany also provides good Japanese stilt grass info.

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June in bloom in rain-drenched Connecticut

The first half of June dropped 10 inches of rain on my Connecticut garden, making the days leading up to June 2013 Garden Bloggers’ Bloom Day soggy. Temperatures remain in the 50’s at night and 70’s during the day when, so often, the sun struggles to shine.

Lush greenery abounds throughout the rain-drenched gardens, dotted by shades of yellow, and blue, and shades of pink ranging from deep to pale to peachy tones.

Native Mountain Laurel, the Connecticut state flower, have been spectacular this year. They line and dot the edges of the woods surrounding our more cultivated land.


In places, foxglove (digitalis, unknown variety) have self-sown along the woodland edge, particularly near my compost piles where seeds must have escaped when spent foxglove spires went into the compost.


I don’t mind the self-sowing foxglove. Bees and hummingbirds love the flowers and deer leave the flowers and foliage alone.

Foxglove spires stand tall above yellow-blooming sedum that mimic the foliage of the small Spiraea ‘Double Play Gold’ in the foreground and Hakonechloa macra ‘Aureola’ at the far end. Blue-green Lady’s Mantle (Alchemilla mollis) and blue-silver Lamb’s ear (Stachys byzantina) contrast against these yellows and the yellow-green Hayscented fern that loves to spread from the woodland edges into my perennial beds.


No matter the time of day these combinations provide a cheery view from the front porch and my office window and help transition into the area just beyond where I hope young viburnum, magnolia, kalmia, summersweet, juniper and clethra eventually form a shrub/small tree backdrop. But for now, ornamental grasses serve as backdrop foliage.


Along the west side of the house, what I call the triangle bed is filled with a river of sedum surrounded by Rose campion (Lychnis coronaria), Lamb’s Ear, and Santolina in the foreground. I’ve planted many different combinations in this bed, many were plant combos deer have found quite yummy. But deer mostly leave this combo alone, only occasionally browsing the tops of yet-to-bloom veronica in the background.


In the rear garden, totally fenced from deer, roses are the most prominent blooms at the moment. They seem happy to take over now that earlier iris have passed and later iris have yet to open.


This peachy Star Rose is accompanied by nearly-open lavender blooms and nearby scabiosa.


Further along in this long narrow bed blooms another Star Rose, Pearl Sevillana (left).


At the far end of the bed is my newest rose, the Blushing Knock Out Rosa ‘Radyod’ (right) which holds her own between two holly shrubs and a white-blooming lilac, and blooms from early June through frost.

Now that you’ve seen my top June picks, it’s time to visit May Dreams Gardens, where Carol hosts Garden Bloggers’ Bloom Day. There you’ll find many, many more gardens to visit.

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