Lithodora Cold Tolerance: How To Overwinter Lithodora Plants

Lithodora Cold Tolerance: How To Overwinter Lithodora Plants

By: Bonnie L. Grant, Certified Urban Agriculturist

Lithodora is a beautiful blue flowered plant that is half hardy. It is native to parts of France and southwestern Europe and likes a cooler climate. There are several varieties of this spectacular plant, all of which tend to spread and make a lovely ground cover.

Is lithodora frost hardy? Keep reading to find out.

Is Lithodora Frost Hardy?

If you want a no fuss, easy to grow, sprawling bloomingbeauty, try growing lithodora. It grows natively in a Mediterranean climate andneeds plenty of water to produce an abundance of flowers. It blooms in springbut in some climates a second bloom in summer can be expected. Northerngardeners may have to provide lithodora winter protection, due to its halfhardy nature.

Cold tolerance for these plants runs in the USDA hardinesszones 6-9. However, some gardeners have learned ways of winterizing lithodoraplants into zone 5. Severe, sustained freezing can damage the stems andpossibly even the roots, where drainage isn’t optimal. While this plant prefersmoderate temperatures and moist soil, it does not do well in southern heat andhumidity. It also cannot thrive in regions with long, extremely coldtemperatures.

Moderate conditions are best for this particular plant. Ifyou are concerned about the plant’s longevity in cold sites, provide some winterprotection with freeze shield cloth or mulch.A potted situation offers the easiest lithodora winter protection.

How to Overwinter Lithodora

Since lithodora cold tolerance is spotty, northern gardenersshould grow the plant in containers and bring it indoors for winter or providea microclimateoutside where the plant has some protection.

Select a location with some screening from drying winds andcold northern weather. A south-facing slope or tucked into a rockeryaway from wind would be ideal. When winterizing lithodora plants, mulch aroundoutdoor plants to protect roots from freezing, while also providing a barrierto many weeds.

Lithodora Winter Damage and Care

If stems are black as spring approaches, they likely gotdamaged in a cold snap. Trim off dead stems to encourage new growth and improvethe plant’s appearance. Alternatively, you can wait until the bloom is over andshear the entire plant back to promote compact growth.

Fertilize in early spring with a timerelease formula. Water in well after applying. Pull mulch away from theplant in spring to allow new stems and growth to emerge.

Harden off plants that were overwintered indoors, beforeinstalling them in the ground or leaving them permanently outdoors for the warmseason.

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How to Winter Carnations

Carnations, or Dianthus, are fairly hardy, short-lived perennial flowers. Prized for their intricate flowers, carnations usually come in white, pink or red hues, but there are some varieties that are more lavender or orange. Carnations are sometimes referred to as annuals, but they aren't true annuals as they do not complete their life cycle in a single year when cared for correctly.. Most carnations live for two to three years before they require replacing, so overwintering the plants properly ensures they live to their full life span.

Snip off the dead flowers and any dead or damaged foliage with a sharp set of shears in fall prior to the first frost. Remove all the dead and fallen plant matter from the bed so that diseases do not overwinter in it.

Lay a 4-inch layer of mulch over the carnation bed after the first hard frost in fall. Use straw or pine boughs, as these offer protection from winter cold and help maintain the soil temperature, which prevents frost heave to the roots.

  • Carnations, or Dianthus, are fairly hardy, short-lived perennial flowers.
  • Carnations are sometimes referred to as annuals, but they aren't true annuals as they do not complete their life cycle in a single year when cared for correctly..
  • Most carnations live for two to three years before they require replacing, so overwintering the plants properly ensures they live to their full life span.

Water the bed as needed to keep it slightly moist throughout winter when the ground is not frozen. In areas with mild winters, carnations may continue to bloom all winter.

Remove the mulch in spring when the carnations begin actively growing again. Fertilize with a balanced fertilizer, such as 10-10-10 analysis, at the rate recommended on the fertilizer label. This encourages fresh, healthy growth from the flowers.


Is Lithodora Evergreen?

When to Prune Lithodora Since the plant is an evergreen, lithodora trimming is common in the early spring, just as winter has ended. Cutting back lithodora after flowering can help growers to maintain plants and to ensure they remain the desired size.

Likewise, can perennials be evergreen? Perennials are long-lived plants that persist year after year. These plants do not have to be planted again each spring like annuals. Evergreen perennials keep their leaves throughout the winter, unlike herbaceous perennials that die back to the ground in cold weather.

Similarly, you may ask, why is my Lithodora dying?

Black Root Rot: This fungus attacks plant roots causing yellowing foliage and stunted plants. Scattered branches may die back. Portions of roots killed by the pathogen are brown and turn black. Burpee Recommends: Make sure the soil is acidic as the disease is less of a problem in soils with a pH of 5.5 or less.

Lithodora. Lithodora is, in any case, easy to grow and flowers well. The evergreen mats of foliage spread slowly to make good ground cover on a rock garden or scree. Unlike many rock plants, lithodora needs a humus-rich soil, rather than a gritty one, so make a special planting pocket for them.


How to Grow Lithodora Species such as Indian paint

It is not recommended to try to grow Indian Paint and other Lithodora species from seeds but to take cuttings in the middle of summer, or to purchase plants from a garden centre.

Lithodora should preferably grow in a sunny (will be ok in a partially shaded) part of the garden, and has a preference for an acidic soil that is moist and well drained. They should be planted from 20 cm (small Lithodora species) to 45 cm (large Lithodora plant varieties) apart.


Glandora, Lithodora, Scrambling Gromwell, Shrubby Gromwell 'Grace Ward'

Category:

Water Requirements:

Drought-tolerant suitable for xeriscaping

Average Water Needs Water regularly do not overwater

Sun Exposure:

Foliage:

Foliage Color:

Height:

Spacing:

Hardiness:

USDA Zone 5a: to -28.8 °C (-20 °F)

USDA Zone 5b: to -26.1 °C (-15 °F)

USDA Zone 6a: to -23.3 °C (-10 °F)

USDA Zone 6b: to -20.5 °C (-5 °F)

USDA Zone 7a: to -17.7 °C (0 °F)

USDA Zone 7b: to -14.9 °C (5 °F)

Where to Grow:

Grow outdoors year-round in hardiness zone

Can be grown as an annual

Suitable for growing in containers

Danger:

Handling plant may cause skin irritation or allergic reaction

Bloom Color:

Bloom Characteristics:

Bloom Size:

Bloom Time:

Other details:

Soil pH requirements:

Patent Information:

Propagation Methods:

From seed sow indoors before last frost

Seed Collecting:

N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed

Regional

This plant is said to grow outdoors in the following regions:

Knights Landing, California

Montgomery Creek, California

Rancho Cucamonga, California

Elizabeth City, North Carolina

Simpsonville, South Carolina

Gardeners' Notes:

On May 24, 2020, Rests from Bryan, TX wrote:

It says plant in sun, but it hates the hot sun here in Zone 8b in south central Texas. It also hates our salty water. If you live in North Texas, I'm sure you would have good luck with this. But anywhere south of Dallas, don't even try to grow it.

On Mar 25, 2019, ripgirl from Gilbertsville, PA wrote:

I have a large boulder retaining wall with a planting bed on top and granite steps in the middle. The first time I saw this being sold as a rock garden plant and being absolutely smitten with any plant that has blue flowers I bought 2 thinking they would look lovely cascading around the steps. They didn't last the summer. Too hot and dry but they are sold as rock garden plants so I was confused.
Undeterred I tried again the next year and planted them on top of the wall where they received some relief from the scorching by larger shrubs. Still dried up. One did come back the next year which I was pleased to see but it did not last the summer. I did not see it the 3rd year.
It is that time of year again and I saw them over the weekend at Home Depot and am tempted to try ag. read more ain but somewhere different. Just not sure they seem to be high maintenance to me.

On Jun 6, 2018, Ja_Al_La from Berlin, MA wrote:

I am absolutely smitten with this plant. I love it. I am still learning how to keep it happy, but so far, I have learned that it hates being soggy and will turn black & miserable if too wet for too long. We tend, here in Central Mass, to have a lot of wetness as our snow cover melts, and my garden beds are often quite wet through this process. I have 4 Lithodora, Grace Ward, in this one particular bed that has settled a bit in the middle and stays quite soggy. I have found that incorporating some expanded shale bits in the soil in which I plant it, helps take up excess moisture. The one Lithodora for which I've done that stayed in good shape, is larger and more covered with those glorious little electric blue blossoms than are the others. The others stayed too wet and turned black. They ar. read more e recovering nicely now, but are well behind the one with the shale chips. I have a fifth Lithodora, GW in another bed a raised bed with a rock retaining surround. It is at the edge of this bed, in near full sun, but with great drainage, and is very happy there spreading, full of blooms and trailing over the rocks. When this plant is happy it's a knock-out, and is one of my very favorite plants. I've had two that completely disappeared at one time and I thought they were done, but they came back. They're small, so far, but promising. Time to get more of that shale, I think, and place it around them. It seems it will tolerate some shade as long as it gets a good bit of sun as well. I do have the recommended acid soil here.

On May 22, 2017, lsjogren from Vancouver, WA wrote:

I've had mine for about 3 years and so far they are awesome. Started as 4" plants and after 3 years they are 2-3 feet in diameter. When in full bloom, absolutely stunning. And one thing that surprised me, the hummingbirds love them. (here in Portland OR area we have Anna's hummingbirds) Here in late May in a season where things have bloomed very late, the lithodora seems to be their best bet for flowers to feed on. I try to include lots of hummingbird plants like Salvias and Agastaches, but they are later bloomers and only have a few flowers so far.

Another plus for this plant: Being in zone 8 you would figure no problem since Monrovia says zone 6-9. But I have had some other types of plants, particularly Salvias, rated zone 6 or 7 that got severely damaged and in s. read more ome cases died in the harsh winter we had in 2016-2017. No problem for the Lithodoras. And they have a few flowers all the time, they even had a few in the middle of winter.

If there are any negatives for these that will affect me that hasn't happened yet. I understand they can get sort of ratty as they get older, although I suppose that is probably generally true for most perennials.

On Apr 15, 2016, 1077011947 from Greer, SC wrote:

I grow Lithodora here in Upstate Sc. It is an evergreen and a profuse bloomer. It blooms all summer and is hardy in my zone 7b/8a zone. I grow it in my Xeric bed with Delospermas , Sago, and Agave. It is beautiful scrambling over the rocks.

On Apr 5, 2015, coriaceous from ROSLINDALE, MA wrote:

The plants look great in the nursery, with electric blue flowers over neat foliage.

In Boston (Z6a), I've tried this several times in well-drained sandy loam that's acid enough to support ericaceous plants. I've had a lot of trouble with the foliage turning black and beginning to die back a few months after planting. The plants may survive the winter but never look as good the second year, and never last long.

Perhaps it's that the irrigation systems give too much water, too often (daily). Perhaps sharp sand would help. Perhaps it's the climate here in southern New England. But I've given up on this plant.

On Mar 23, 2015, mayclinhelpmeet from Alta Loma, CA wrote:

Are you willing to be challenged a bit for beauty sake?

Grace Ward Lithodora flowers in intense, deep true-blue tiny blossoms covering the plant once a year for about 4 weeks in the Southern California hot Inland Empire. The rest of the year there are a smattering of flowers throughout its low (4-5") dark green leathery narrow foliage. Takes 3 years to expand to about 3' in diameter in our poor but amended soil with moderate water the first year.

It will produce some volunteers under the main plant. I sweep away mulch from under the plant as it grows to encourage this. It can be finicky & die seemingly without cause. If I plant 3, I seem to invariably lose one. At times it will die back in the center of the plant. I attribute this to our highly alkaline, rock. read more y soil. With a little lower pH & more organic materials in soil, I don't think I would experience these problems as much.

But it is still my favorite flower of all. The blue is stunning when the whole plant blossoms in spring. There is nothing like it. I have purchased it at Lowes in March when it blooms & at Mt. Fuji Garden Center in Upland, CA, & at Sunshine Growers in Ontario, CA.

On Jul 22, 2014, tavira from Tavira,
Portugal wrote:

I have been struggling with the plant for a year. I bought it with superb gentian coloured flowers. I planted it in the shade, and it struggled, I planted it in the sun, it struggled some more, so I dug it up and put it in a pot, first in the shade, then in the sun. Still struggling, and now the leaves are going variegated, which I do not like. It is pretty hot here in Portugal, about 35C, so I will try the shade once more. Have just seen on Google that it needs acid soil, which you don't mention.
Need I say it has not flowered since I bought it? If I had not seen the flowers, it would have been compost months ago. Grateful if anyone has any suggestions??

On Feb 17, 2014, hipgranny63 from Edmonds, WA (Zone 8a) wrote:

I've had this plant in my rock garden for a couple of years now. It started out with just three or four 4" pots, which spread to an area that's about five feet square within two years. It gets full sun and drip irrigation during the summer. It drapes itself beautifully over the rocks, but now, even though it is still mostly green, looks untidy and parts of it is black, especially under the cascading areas. So, I'll take the hedge trimmers to it next month and fertilize it to stimulate new growth. All the literature says to prune only after it blooms, but I've also heard from my friends that what I intend to do should be just fine. Will report back as to my success.

On Aug 30, 2013, esteve59 from Annapolis, MD wrote:


I have planted this at least 4-5 times. the first time it lasted thru a mild winter. but most of the time it dies even if I forget to water it.
not very drought tolerant. which is confusing since because I thought it comes from a Mediterranean climate.
It is such a beautiful shade of blue.

On Jun 20, 2013, 01cookie from Halfmoon Bay, BC, BC (Zone 8a) wrote:

Love this plant, just wish I could get it to root starter plants more easily.
I planted a starter plant from a 2 inch pot into my rock garden in 2008 and now in 2013 it cascades approximately 4 feet down the rocks and is beginning to grow on the sidewalk as well as up a trellis on the fence. It is amazing in that this plant only has one center root and has not self rooted anywhere to support such a big plant.
From early spring to late fall there always are some blossoms on this plant and the bees just love it. What a beneficial plant.
I've never trimmed or fertilized this plant and it handles drought very well. All I did was mix healthy, slightly acidic well draining dirt (mainly peat, loam and horse manure) when I started the rock garden and the Pacific North West co. read more ast climate has handled the rest.
Recently my husband rolled part of this plant out of his way and left it rolled over for a day it suffered immediately but recovered very quickly.
I've never posted a picture before but I will try today so you can see this beautiful plant.

On May 21, 2012, bendipa from London,
United Kingdom wrote:

I have been growing this alpine in a container in John Innes 2 compost for the first time this year. It produced a flush of beautiful blue gentian coloured flowers. This flush is just finishing and the leaves which were a healthy looking green a few weeks ago have now turned black and died as did the whole plant a month later

Bought a second Lithodora and that one was planted in the ground. This time it thrived.

On May 2, 2012, rgoddard13 from Fort Mill, SC (Zone 7b) wrote:

I neglected my garden last year and this thing survived a mild drought in clay soil. Despite this treatment it rewarded me with the brightest, most vibrant flowers of all my plants.
After a little water and fertilizer it went crazy yielding flowers for longer. I am in season 3 and have yet to experience the doughnut in the middle.

On Aug 19, 2010, Marjaliisa from Sonora, CA wrote:

Love! the color. Folage and fabulous flower color. Problem with the center turning black w/the edges continuing to be green and flower. Too much water? When sheared back, sends up new growth and looks like a new plant. They are planted in not so great amended (mostly decomposed granit), but with good drainage. Any ideas to offset the dieback in the center?

On Nov 18, 2009, bonehead from Cedarhome, WA (Zone 8b) wrote:

This plant is a gorgeous true blue and I love it in full bloom, but unfortunatly I don't seem to have much luck with it. It often gets leggy and woody, sometimes whole sections just turn black and die while the rest limps along. I've planted it probably 4 times or more. My latest planting is doing pretty good, maybe I've found the right combo of site/drainage/etc. If so, I'll upgrade to a positive experience.

On Mar 7, 2009, skttlsno1 from Loris, SC (Zone 8a) wrote:

I've found that since I live in the South, they do best with only morning sun. They can't tolerate the full sun down here. Beautiful as a groundcover around one of my oak trees.

On Apr 27, 2008, WombatFamily from Brenham, TX (Zone 8b) wrote:

Had to try a little with this plant. Terrible in a pot. Dying in a sunny spot. Ones at the back of the garden that get some sun but are mostly shaded by other plants are doing very well.

On Mar 29, 2007, ineedacupoftea from Denver, CO wrote:

This plant tolerates absolutely no drought. That is how I killed mine. I do not mean prolonged drought, but conditions that are fairly normal in many gardens that are not damaging if not beneficial to many plants. It is, however, quite pretty and woudl be quite at home in other gardens around the country.

On Mar 25, 2007, HgNi2006 from Vallejo, CA wrote:

I'm not terribly happy with this plant. I put two in pots next to my fountain a year ago and they have looked dead/woody/leggy ever since. Now one has bloomed and looks good, but the other looks bad. Maybe they are best as a groundcover?

On Jun 30, 2006, elaine_h from Conyers, GA (Zone 7b) wrote:

Planted this last summer. It survived our mild winter (zone 7b)at the edge of the cone flower bed in partial sun and is doing very well this summer but getting somewhat leggy. I will attempt to prune back the center a bit this fall. I have enjoyed this plant for it low growing spreading color. Looks good under blooming perennials.

On Oct 13, 2002, PotEmUp from Fremont, CA (Zone 9a) wrote:

Starts off nicely as a ground cover, but becomes somewhat woody as it ages.


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