How to winterize perennials?

Preparing Perennials for Winter

Tips

In cold-winter areas, stop fertilizing perennials by midsummer to encourage them to slow their growth and harden off for winter.

In warm-winter areas, fall is a good time to plant perennials. However, in winter check for signs of disease, especially during wet periods, since the plants are growing slowly and conditions are right for rotting to occur.

After a season of enjoying the blooms from your perennial flower garden, late fall is the time in cold-winter regions (USDA Climate Hardiness Zones 8 and colder) to prepare the beds for winter. Taking good care of beds in fall will help them thrive next spring and summer. Gardeners in warm-winter areas where frost and snow are rare need only to keep the beds cleaned up and replace diseased or worn-out plants as needed. Gardeners in all other climates can follow these steps.

Tools and Materials

  • Pruners
  • Shovel
  • Compost
  • Mulch or row cover

Dig up Bulbs. After the first frost has struck and foliage begins to yellow and die, cut back the foliage, dig, and store tender perennial bulbs such as dahlias and gladiolus that can’t survive the winter in the ground in a cold climate. When digging, be careful not to damage the underground bulb or tuber.

Water and Cut Perennials Back. In dry-winter areas that don’t freeze or have little snow, water perennials once a month to keep them alive and healthy. In all other areas, cut back on watering to help plants harden off in preparation for winter. On perennials that have finished for the season, cut back stems to 6 to 8 inches from the ground.

Feed Plants. Fall is a good time to feed perennials by working in a 4- to 6-inch-thick layer of compost around the beds. The compost slowly breaks down, releasing nutrients to the plants and improving the soil structure.

Mulch. After the ground freezes, remove old mulch and replace it with hay, evergreen boughs, or floating row covers. This extra layer protects tender perennials and helps catch and hold snow, which will also insulate the bed.

Get Your Perennials Ready for Winter

Prepare your perennials for winter! Most perennials can be cut down after the first killing frost; others can add interest or help birds and beneficial insects during the winter months. See our tips.

CutTING BACK Perennials

After several hard frosts, most perennials can be cut back. To cut back your perennials, use bypass pruners and make clean cuts through the stems of the plant. I usually leave 6-inch stubs so I can find the plants next spring.

Plants need to be cut back after frosts to avoid disease and pest problems in the spring. Bee balm and phlox are prone to powdery mildew so cut them all back once they’re gone. Remove all hosta after a hard frost, including any leaves on the ground, as they harbor slug eggs. Other perennials to cut back include bearded iris, peony, daylily, veronica, sunflower, salvia, shasta daisy, clematis, columbine, catmint, and yarrow.

Don’t be in a rush and be sure until a few hard frosts. Even if the flowers or leaves are dead, the roots are reclaiming energy from the dying plant for healthy growth in the spring.

Leave Some Winter Interest

Leave a few things standing for winter interest. The blackberry lily Belamcanda looks great until heavy wet snow finally knocks it down. Ornamental grasses add movement and sound to the landscape. I let the agastaches and coneflowers and rudbeckia stand for the birds to enjoy. Self-seeding plants will provide you with volunteers next spring to move to new spots or share with friends.

Many perennials, like this penstemon, have already started to form leaves for next year at the base of the plant. When cutting back be sure to leave these rosettes of green.

Some Perennials NOT To Cut

Some perennials (including the alpines above) and epimediums, hellebores, candytuft, primulas, dianthus, hens & chicks, heaths, and heathers are considered evergreen and should not be cut back in the fall.

This hellebore is considered an evergreen and should not be cut back in the fall.

Do not cut back marginally hardy perennials such as garden mums (Chrysanthemum spp.).

Clean Up Debris

As with the vegetable garden, any diseased or bug infested plant material needs to go—far away. Don’t put it in the compost pile. Debris from things like rusty hollyhocks, peonies with powdery mildew, leaf-spotted delphiniums, and other fungal-infected flowers should be removed from the garden.


Leaves from a peony infected with powdery mildew should not be composted.

Don’t Fertilize in the Fall

Fertilizing in autumn encourages new growth that will just get killed when cold weather hits. Compost is not considered a fertilizer; it is a soil conditioner so feel free to add that in the fall. If your soil test indicates that you need lime, it can be applied in the fall also.

Weeding

Before the ground freezes, do a final weeding. The more weeds you can get out now, especially those that have seeds, the fewer weeds you’ll have to deal with in the spring. Edge your beds for one last time and you’ll start the year with a neat and tidy look.

To Mulch or Not to Mulch

If you are growing plants that are hardy in your zone and live where snow cover is plentiful each winter you probably don’t have to worry about mulching your garden, though it’s always insurance to give them some extra protection. It’s newly planted perennials that are the exception. Definitely tuck some mulch around them for their first winter.

The purpose of a winter mulch is to keep the soil temperature even and prevent heaving of roots due to alternate freezing and thawing of the ground. Waiting until the ground is frozen before mulching is not only best for your plants but also discourages rodents from making a cozy home there. Use a mulch that does not pack down and smother your plants. Shredded leaves, pine needles, straw, or evergreen boughs are good choices. Snow provides the best insulating mulch, it goes down gradually and melts gradually.

Learn more about mulching your garden.

Watering the Garden

If you live where it has been dry this growing season, keep watering your garden until the ground freezes. Usually there is plentiful moisture in the fall but many areas experienced drought conditions this summer and the ground is dry. Plants that are water stressed will have a tough time surviving the winter.

The more work you do in your perennial garden this fall, the less you’ll have to do next spring.

See more about overwinterizing plants in the garden—from roses to rosemary.


The big advantage to planting perennials in your garden is that you will not need to plant them again next year. With the ability to live through the winter weather and come back again next spring, perennial flowers are loved for their durability and consistency. However, you do need to take some steps in order to give them the best possible chance of getting through the winter in good condition. Just like any other type of plant, perennials will not survive if they are neglected.

Plan Ahead

To care for your perennials properly in the winter, you will actually need to have a plan in place during the summer. Specifically, you will want to halt the fertilizing process during sometime in the summer so you can slow down the growth of the plant and get it ready for the winter ahead. This is a particularly important tip in cold weather areas.

Cut Them Back

This is probably not a surprising tip to find here, but it is important nonetheless. As you may know, you will want to cut your perennials back before the winter weather settles in. When the growing season is over, cut the stems down all the way to the point where they are only six to eight inches above the top of the soil.

Consider Watering

If you live in a part of the world where freezing temperatures don’t often occur in the winter, you might need to water your perennials on occasion. Of course, this advice only applies if you live in a dry climate. Areas which receive a lot of rain will have no need for a winter watering schedule. Even if you do live in a dry area, you should only need to water roughly once per month to keep the perennials in good condition until spring.

Use Mulch

For those in a cold climate – particularly an area which receives snow – it is a good idea to use mulch as an insulator during the cold winter weather. Fall is a good time to remove any old mulch you might have had in the beds and replace it to help protect the perennials from what could be a harsh winter season. This layer of insulation just may be what allows your perennials to make it all the way through to spring without any signs of trouble.

Consider Storing Bulbs Away

There are certain types of bulbs – like dahlias – which are not tough enough to survive the cold winter in the ground. If you are dealing with a cold climate, you may need to dig these bulbs up and store them in a more suitable environment until the weather warms up again.

Perennials are a great addition to any garden, but they require attention just like any other plant. We hope the simple tips above will help you care for your perennials successfully even when the cold winter weather arrives. Good luck!

Winterizing Perennials

Guide to Winterizing Perennials

Closer to the end of autumn it is time to think about preparing perennial plants for winter in order to help them survive the potentially challenging weather conditions of winter months.

Keep reading to find out the ways to prepare your perennials for winter and to have them revived and healthy ready for new growth in the spring.

A Step by Step Guide

First of all, it is essential to decrease watering – cut down on the water levels slowly, every time reducing the amount of water you give to the plants. A lower level of moisture in the soil will help your perennials to harden so they will be ready for the changes in weather conditions as winter approaches. It will increase their endurance and cold resistance.

The bulbs of some perennials will not be able to survive hard frosts and snow of winter if you leave them in the ground. You should therefore wait until the first frost and dig up the bulbs of Gladiolus, Dahlias and other delicate plants. Store them until spring in a place where they will not be affected by moisture and heat.

If you’re perennial plants have finished flowering, cut their stems leaving only around seven inches from the base. Do not worry; they will grow back when the time is right. The trimmed stems can be dug in the soil to enrich it with organic matter, but make sure they are not affected by any disease.

Any diseased perennials should be removed from your garden completely: dig them out and throw out. It is important to remember to avoid putting compost around any plants affected by diseases; otherwise the compost can spread the infection to other plants around the garden.

To enrich the soil along with feeding your plants for the long period of cold: put a layer of compost around every plant. The layer should be around 5 inches thick.

Remember that mulching is an essential part of winterizing perennials. It is necessary to mulch regardless your decision to keep the dead foliage in your garden or to remove it. In order to insulate your flower beds, remove the old mulch and put some fresh hay or straw around your plants. It will help them to survive no matter how much snow falls during the winter season.

After you have trimmed the plants, stop watering them.

Following the first frost you should stop watering all the perennials in your garden.

Avoid fertilizing your plants in the second part of summer and all through autumn: it will slow down the growth and help them adjust to severer conditions.

Sometimes newly planted trees and shrubs need some extra protection for a couple of winter seasons until they establish properly.

Any plant that seems to be too susceptible to snow and cold of winter should be hidden under a seasonal shelter. Anything will do: plastic pots, thick paper bags, straw and shredded leaves. Of course, if you care for the aesthetic look of your garden in winter too, it would be better to make some shelters with a more appealing look. But if you are in a hurry to save your plants, you can use anything that might be suitable for this purpose as long as it provides some protection for the plants.

Follow the basic rules of winterizing perennials, treat your plants with affection and patience, take care of them, and enjoy their bloom as they thrive again in spring.

  • Garden Mulches
  • Composting
  • Pot Gardening

Preparing the Garden for Winter

Perennials 101, Seasonal Activities through the Year

Moving or dividing perennials in the autumn is a great way to reduce your work next spring. The cool, moist weather is an ideal time for perennial roots to become well established, even in cold-winter regions.

Gardeners often ask us when the best season is to move specific perennials, so we have a working “rule of thumb” for timing.

John’s Rule-of-Thumb for when to move or divide perennials:

  • If the plant blooms between early spring and late June, then early fall division/moving is ideal.
  • If the plant blooms after late June, then early spring division is ideal.

Exceptions to the rule are: Peonies (move/divide in fall only), Oriental Poppies (move/divide in August), Bearded Iris (move/divide in July through September) and true Lilies (move/divide in mid to late fall).

Of course, you can always break the rules and see what happens. Just remember that if you move or divide a big, bushy perennial always cut back the foliage by at least half to prevent serious wilting. This helps to keep the leaf mass in proportion to the reduced number of roots!

Once Autumn has truly arrived….

A couple of good, hard frosts makes a big difference in the garden. Some perennials immediately begin to go dormant, while others seem to want to hang on into late fall. To those new gardeners out there, we encourage you to consider leaving most perennials alone in the fall if you are unsure of what winter interest they might provide. It would seem a shame, for instance, to cut back those big, beautiful clumps of ornamental grasses in the fall, ruining any opportunity to hear them rustling in the winter winds, or to enjoy the contrast of their wheat-coloured stems against clean, fresh snow. Winter interest is entirely subjective, and only you can decide what is attractive to your eye, or what looks tired and messy.

Here are a few tips and ideas:

  • fall-blooming ornamental grasses usually remain gorgeous well into the winter. It seems a real shame to cut them back to the ground before late winter or early spring. Some gardeners are now waiting even beyond THAT, and enjoying the effect of wheat-colored grass clumps contrasting with spring-flowering bulbs!
  • seed-heads of certain perennials provide food for finches and other birds, and they look great against a blanket of snow. Most late-flowering daisy-type perennials are on this list (like Rudbeckia and Purple Coneflower), but others with nice seed-heads and sturdy stems include: Achillea, Agastache, Aster, Astilbe, Baptisia, Buddleia, Chelone, Cimicifuga, Eryngium, Eupatorium, taller Sedum, and a few others.
  • there is a common theory that the dead tops of perennials help to trap the snow, which is the very best insulation against cold temperatures. In regions with erratic snowcover and mid-winter thaws, the tiny bit of extra snow that is actually trapped may in fact be of little benefit.
  • many perennials have very little winter interest. Cutting these types back in the fall effectively “clears the clutter” and makes the ones you leave look even better. Consider cutting these down in late fall: Alchemilla, Anemone, Campanula, Centaurea, Coreopsis, Delphinium, Dicentra, Euphorbia, Geranium, Hemerocallis, Hosta, Lychnis, Monarda, Nepeta, Oenothera, Phlox (tall types), Trollius, Veronica.

Certain perennials naturally carry over a low clump of evergreen leaves near the ground, known as a “rosette“. Although you can trim the upright stems back, these lower leaves need to be left alone in the fall. By spring they often look a little worse for wear, but a quick trim with scissors (only the brown or dead parts) will tidy the plants up again. In this group are: Achillea, Aster, Coreopsis, Digitalis, Erigeron, Fragaria, Gaillardia, Geum, Heuchera, Bearded Iris, Shasta Daisies, Penstemon, Poppies, Polemonium, Potentilla, Salvia, Scabiosa, Stachys, Tiarella, Verbascum, and many of the hardy ferns.

Evergreen perennials and alpines should not be trimmed in the fall. Usually the best time to trim these is immediately after blooming, if at all. Leave these ones alone in the fall: Ajuga, Alyssum, Arabis, Armeria, Artemisia ‘Powis Castle’ and ‘Huntingdon’, Aubrieta, Aurinia, Bergenia, Cerastium, Corydalis, Dianthus, Epimedium (trim in late winter, before new buds appear), evergreen Euphorbia, Helianthemum, Helleborus, Heuchera, Iberis, Kniphofia, Lamium, Lavender, Liriope, Origanum, Phlox (creeping types), Primula, Pulmonaria, Sagina, Saxifraga, Sedum (many creeping types), Sempervivum, Teucrium, Thymus, Viola.

Certain woody-stemmed perennials are better left alone in the fall, and pruned back in the spring, leaving about 6 inches of woody stem for the new buds to appear from. These include: Buddleia, Caryopteris, Erysimum ‘Bowles’ Mauve’, Fuchsia, Hypericum, Lavatera, Perovskia (Russian Sage), Phygelius, Santolina.

And, finally, certain perennials with associated disease or insect problems should not only be cut back in the fall, but care should be taken to remove and destroy the leaf litter below them, where insects and pathogens may be hiding. Among these: Alcea (Hollyhocks), Aquilegia (Columbine), Crocosmia, Delphinium, Helenium, Heliopsis, Hemerocallis (Daylily), Iris (Bearded types, leave green leaves alone but remove all dead ones), true Lilies, Monarda, Peonies, Summer Phlox, Tricyrtis, and Veronica (tall types).

Late Fall mulching – do you need to bother?

If the perennials in your garden are mostly things that are rated hardy for your region or colder, the expense, time and effort that goes into late fall mulching is hard to justify, in many cases. The idea of a mulch is to add a layer of insulation on top of the soil, preventing sudden changes in soil temperature (from either deep freezing OR thawing), changes that can wreak havoc to the root systems of tender plants. Regions with reliable snow cover already enjoy the advantages of a natural snow mulch — nature’s insulation. However, where snow is unreliable, a late fall mulch can help in certain cases.

Consider trying it in these instances:

  • Autumn-flowering ornamental grasses, if you live in Zones 4, 5 or 6 and they were planted after the beginning of August.
  • Japanese Anemones, if you live in Zones 4, 5, or 6 and they were planted after mid July. Probably only required for the first winter.
  • You are trying to grow any perennials rated one or more Zones warmer than your region. e.g. you live in Zone 4 and are trying to grow a Zone 5 or 6 plant.

Mulching materials should be organic matter that remains loose and won’t pack down to suffocate your plants. Good choices might be dried leaves (a mix of different types is best — not too heavy on the maple leaves), clean straw, chopped dead tops from other perennials, evergreen boughs from pruning, marsh hay (lucky you, if you have it available!).
Bad choices: peat moss, garden soil, newspaper, sheets of plastic or garbage bags. All of these have a smothering capability. Some gardeners are also reporting good success using various foam products available for this at garden centers.

Mulch can be simply piled high on top of your plants, but a depth of 6 to 8 inches or more is ideal. Those dandy mulch forms that are used on roses might be handy, or you can easily make your own cages from chicken wire.

A word about Hardy Mums

Hardy Mums — more aptly called Garden Mums these days, are something gardeners often ask us about. We thought it would be worth explaining a thing or two about the modern selection of Chrysanthemums and how they respond, so gardeners better understand them.

Basically, Mums are mostly now being bred to produce exuberant cushions of stunning, glorious colour in the containers at the time you buy them. For the most part, they are being bred as a temporary holiday plant, to be enjoyed while in flower and then discarded afterwards. To be honest, the price of Mums in most regions makes this an affordable thing to do.

The hassle of overwintering them and then pinching several times each season in future years (May through July) may not be worth the effort in the end. Mums need regular fertilizing, a full sun location, regular insect control, and constant watering through droughts in order to ever again achieve that perfect cushion look they had when you bought them. Without all of those things, more often than not they end up looking tall, spindly and bedraggled in their second season. Gardeners in northern regions may also find that their Mums never again flower before the frosts kill the buds.

So… if you choose to give it a try, mulch your mums well after the ground freezes. Check them periodically in late winter and spring to make sure the frost has not heaved them from the ground, and press the rootball back in gently if it has. In spring, cut back the dead foliage and wait until about the end of May to see if they survived or not.

Need help with storing your tender bulbs?

Here is a handy link with lots of details on how to go about storing those tender Summer-blooming bulbs, like Dahlias, Cannas, Calla Lilies, etc. This links to lots of other bulb information as well, so it’s a handy resource for the perennial gardener!

Perennials Care Guide

While you enjoy your perennials for their fantastic foliage or beautiful blooms, it is really the roots you’re buying — because the roots allow the plants to come back every year. Use these tips to make sure your perennials get off to the right start.

Container-grown perennials are easy to plant and commonly available. Start by digging a hole that’s a little wider but no deeper than the pot your new perennial came in. Loosen the roots and spread them out if the plant has become rootbound (when the roots start to grow in circles around the edge of the pot). Then firm the soil in around the roots and water well.

Learn more about growing perfect perennials.

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Bare-root perennials are typically less expensive than container-grown versions of the same plant. They’re usually available in early spring and are sold as their name suggests — just the plant roots, usually packed in peat moss or a similar material. Soak the roots in water, before planting them in the ground.

Planting Tips

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Water your perennials well after you plant them. Then lay a 2- to 3-inch-deep layer of mulch over the soil around your new plants. The mulch will help the soil hold moisture and prevent weeds from growing.

Give taller perennials such as delphiniums, hollyhocks, and peonies support by staking them. Anchor single stems by inserting a rod or sturdy stick into the ground and tying the stem to it. Keep clump-forming plants with multiple stems standing by growing them through a hoop (as shown here).

Regularly deadhead and divide your perennials to keep them healthy and looking beautiful.

Deadheading

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Deadheading simply means cutting the faded flowers off your plants. It makes your plants look better and it prevents them from setting seed so you don’t have a mess of coneflowers, phlox, columbine, or heliopsis seedlings popping up in your garden.

Happily, many perennials respond to deadheading by putting out more blooms. Examples of rebloomers include threadleaf coreopsis, delphinium, phlox, veronica, and yarrow.

Learn more about deadheading.

Dividing

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One of the best things about perennials is that they grow bigger and better each year. But many will start to crowd themselves out if they get too big. Keep them performing well by digging them out of the ground and splitting them into smaller chunks every three or four years.

Early spring and fall are the best times to divide most perennials. A couple of exceptions include bearded iris and hosta; split these perennials in summer.

Learn more about dividing perennials.

Watering

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There’s no one-size fits all rule for watering perennials. Some varieties stand up to drought and others need to be kept moist all the time.

Keep your plants healthier and make watering a breeze by grouping plants by their water needs. Moisture-loving perennials include lysimachia, cardinal flower, perennial hibiscus, astilbe, marsh marigold, turtlehead, and pitcher plant. Perennials that do better in dry soil include lamb’s ears, lavender, yarrow, salvias, thyme, penstemon, and purple coneflower.

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Some perennials are prone to a common disease called powdery mildew. It creates a gray or white fuzzy growth on the leaves. To keep this, and many other fungal diseases at bay, water perennials in the morning or early afternoon hours and use a soaker hose (shown here at the right) instead of a sprinkler. You often see powdery mildew on asters, bee balm, black-eyed Susan, columbine, coreopsis, phlox, and salvias.

Test Garden Tip: No matter what perennials you’re growing be sure to keep them well watered the first year. That allows them to become well established.

Feeding

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If you have rich soil or amend it with compost or other forms of organic matter on a regular basis, you probably won’t need to feed your plants. But if you’re cursed with poor soil, fertilizing can be helpful.

In most cases, all you need is a general-purpose garden fertilizer. Be sure to follow the directions on the packaging.

You might be tempted to use more fertilizer than is recommended, but you can have too much of a good thing. Overfertilization may make your plants flower less, suffer root injury, or even kill your perennials.

Winter Care

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Perennials that are reliably cold hardy in your region shouldn’t need any special winter care. But spreading a layer of mulch over them after the soil freezes can help prevent winter damage during an especially cold season.

Many gardeners like to leave the dead stems of their perennials standing all winter as many (including purple coneflower and black-eyed Susan) provide food for birds. In snowy areas, perennials can help to catch snow, which is among the best winter mulches.

Winter Care of Perennials

Now that the temperatures are cooling off, or shall I say cold, it is time to put your perennials to bed for the winter. For the most part, perennials will overwinter here just fine by following these simple steps.

Cut

Once your perennials start to lose their leaves, die back and go dormant, you can go ahead and cut them back in late fall or early winter. By cutting them back to 6‐8” above ground the stem will be able to hold snow in place which helps to insulate your plants. You can also wait until spring to cut them back if you prefer, however mulch is easier to apply if they are cut back.

Mulch

Either way you’ll want to mulch your perennials with 2‐5” of mulch for the winter. The mulch can be any kind of mulching material such as hemlock mulches, pine post peelings, dried grass clippings, etc. It serves the dual purpose of keeping in winter moisture, and acting as insulation for the root system. Our perennials risk losing their root systems from tissue damage with our continuous freezing and thawing conditions. It is best to wait until the ground has frozen lightly before applying mulch, this insulation will keep the ground frozen.

Even though many plants appreciate protective winter mulch, there are some perennials that do better without additional winter mulch. These plants are intolerant of being too wet throughout the winter and risk root rot or losing their centers. On the flip side, some of our perennials are very tender and require extra winter mulch, five inches or more for adequate protection. Below are two lists of some of these perennials.

Water

Remember to provide winter water to all of your perennials during dry spells when the top portion of ground has thawed and can accept water. Water every 4‐ 6 weeks during these dry periods where there is no snow cover. Keep in mind that your perennials will wake up at different times in the spring, so don’t give up hope if you don’t see signs of life right away!

Perennials that prefer no additional mulch through winter

  • Aster Aster spp.
  • Basket of Gold Aurinia saxatilis
  • Black-eyed Susan Rudbeckia fulgida
  • Blanket flower Gaillardia aristata
  • Creeping Phlox Phlox subulata
  • Coreopsis Coreopsis spp.
  • Daisy, Shasta Daisy Chrysanthemum spp.
  • Daylily Hemerocallis spp.
  • Delphinium Delphinium spp.
  • Dianthus (Pinks) Dianthus spp.
  • Evening Primrose Oenothera spp.
  • Flax Linum spp.
  • Gas plant Dictamnus spp.
  • Gayfeather Liatris spicata
  • Geranium Geranium spp.
  • Geum Geum spp.
  • Germander Teucrium spp.
  • Globe thistle Echinops spp.
  • Grasses – most ornamental grasses
  • Hens & Chicks Sempervivum spp.
  • Iris Iris spp.
  • Lamb’s ear Stachys byzantina
  • Larkspur Delphinium spp.
  • Mexican Hat Ratibida spp.
  • Pasqueflower Pulsatilla spp.
  • Pearly Everlasting Anaphalis spp.
  • Penstemon Penstemon spp.
  • Poppy Papaver spp.
  • Purple Coneflower Echinacea spp.
  • Pussy-toes Antennaria spp.
  • Rockcress Arabis spp.
  • Russian Sage Perovskia atriplicifolia
  • Salvia Salvia spp.
  • Silvermound Artemisia schmidtiana
  • Soapwort Saponaria spp.
  • Snow-in-summer Cerastium tomentosum
  • Spiderwort Tradescantia spp.
  • Spurge Euphorbia spp.
  • Stonecrop Sedum spp.
  • Sulfur flower Eriogonum umbellatum
  • Sunrose Helianthemum spp.
  • Tansy Tanacetum spp.
  • Thrift, Sea pink Armeria spp.
  • Thyme Thymus spp.
  • Valerian Centranthus spp.
  • Yarrow Achillea spp.

Tender perennials that prefer extra mulch ( 5” +) throughout the winter

  • Ajuga Ajuga repens
  • Bergenia Bergenia cordifolia
  • Bulbs
  • Chrysanthemum Chrysanthemum morifolium
  • English Daisy Bellis perennis
  • False Mallow Sidalcea spp.
  • St. John’s Wort Hypericum patulum
  • Lavender Lavandula spp.
  • Pincushion Flower Scabiosa caucasica
  • Plumbago Ceratostigma plumbaginoides
  • Wallflower Erysimum spp.

Sources

  • Armitage’s Garden Perennial: A Color Encyclopedia. 2000. Allan M. Armitage. Timber Press.
  • A‐Z Encyclopedia of Garden Plants. 1996. Christopher Brickell and Judith D. Zuk. DK Publishing.
  • Manual of Herbaceous Ornamental Plants. 1994. Steven M. Still. Stipes Publishing.

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