Zone 5 Annuals – Choosing Cold Hardy Annual Plants

Zone 5 Annuals – Choosing Cold Hardy Annual Plants

By: Darcy Larum, Landscape Designer

An annual is a plant that completes its life cycle in one year, meaning it sprouts from seed, grows and forms flowers, sets its seed and dies all within one growing season. However, in cooler northern climates like zone 5 or lower, we often grow plants that are not hardy enough to survive our cold winters as annuals.

For example, lantana is a very popular annual in zone 5, used to attract butterflies. However, in zones 9-11, lantana is a perennial and actually considered an invasive plant in some warm climates. In zone 5, lantana cannot survive the winter, so it does not become an invasive nuisance. Continue reading for more information on common zone 5 annuals.

Growing Annuals in Zone 5 Gardens

With frost being a threat as late as May 15 and as early as October 1, zone 5 gardeners do not have a very long growing season. Oftentimes, with annuals, we find that it’s easier to purchase them in spring as small plants rather than grow them from seed. Buying already established annuals allows us that instant gratification of a pot full of blooms.

In cooler northern climates like zone 5, usually by the time spring and nice weather comes, we all have spring fever and tend to splurge on the big full hanging baskets or annual container mixes at our local garden centers. It is easy to be fooled into thinking spring is here by a beautiful sunny, warm day in mid-April; we usually allow ourselves to be fooled like this because we have been craving warmth, sun, flowers and green leafy growth all winter.

Then a late frost happens and, if we are not prepared for it, it can cost us all those plants that we jumped the gun and bought. When growing annuals in zone 5, it’s important to pay attention to weather forecasts and frost warnings in spring and autumn so that we can protect our plants as needed.

It is also important to note that many of the beautiful, full plants we buy in spring have been grown in a warm, protective greenhouse and may need time to adjust to our drastic spring weather patterns. Still, with a careful eye on weather changes, zone 5 gardeners can enjoy many of the same beautiful annuals that gardeners in warmer climates use.

Hardy Annuals for Zone 5

Below is a list of the most common annuals in zone 5:

  • Geraniums
  • Lantana
  • Petunia
  • Calibrachoa
  • Begonia
  • Alyssum
  • Bacopa
  • Cosmos
  • Gerbera Daisy
  • Impatiens
  • New Guinea Impatiens
  • Marigold
  • Zinnia
  • Dusty Miller
  • Snapdragon
  • Gazania
  • Nicotiana
  • Flowering Kale
  • Mums
  • Cleome
  • Four O’ Clocks
  • Cockscomb
  • Torenia
  • Nasturtiums
  • Moss Roses
  • Sunflower
  • Coleus
  • Gladiolus
  • Dahlia
  • Sweet Potato Vine
  • Cannas
  • Elephant Ear

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Drought Tolerant Annuals

No matter where you live, water is a precious resource. Some of us need to conserve more actively than others, but none of us would willingly waste water. So why not plant drought tolerant flowering annuals? In addition to saving on your water bill, you'll spend less time on garden maintenance -- and that's welcome news for every busy gardener. Here are five excellent annuals that thrive in dry growing conditions.

Spider flower, cleome (Cleome hassleriana)
Cleome is an excellent annual for the back of a sunny border or a wild flower meadow. In a few short months this annual can grow four or five feet tall and two feet wide. Stems branch without pinching and may need to be staked as they get larger. Cleomes are sun lovers and grow best with at least six hours of direct sun. Blooms may be white, pink, lavender, and magenta. In too moist soils foliage will turn yellow and the plants will not thrive.

Ice plant (Delosperma spp.)
Technically this succulent plant is a perennial (some species are winter hardy to USDA Hardiness Zone 5 in soils with perfect drainage), but depending on your USDA hardiness zone, you may use it as an annual (like I do!). Daisy-shaped flowers come in yellow, white, and magenta ice plant foliage is narrow, smooth, succulent, and grayish green. Some varieties spread to provide excellent ground cover, while others are more clumping. They grow best in sandy soils and full sun and do well both in containers and in the ground.

Licorice plant, curry plant (Helichrysum petiolare)
Licorice plant comes in several shapes and colors, and all of them are drought tolerant. Its leaves and stems are woolly this is a common trait on drought tolerant plants, as the hairs on the plant slow the evaporation of water from leaf tissue. Licorice plant is usually grown for its foliage rather than its small, yellow flowers. Leaves may be gray-blue, chartreuse, or multi-colored. Licorice plant grows well in sandy to average soils. It is a sun lover and may get leggy if it doesn't receive enough light. Pinch the growing tips to encourage branching.

Lantana (Lantana camara)
Lantana gives so much and asks so little four inch pots planted in May are the size of small shrubs by August. Lantana tolerates poor soils and blooms best in full sun. Its flowers are irresistible to butterflies. Flowers may be pastel (lavender, cream), vibrant (yellow, vermillion), or multicolored. This plant will bloom steadily and prolifically until frost whether you deadhead or not. Most lantanas are upright growers with stiff branching stems, but L. montevidensis has a weeping growth habit.

Moss rose, purslane, portulaca (Portulaca grandiflora)
Moss rose is a showy groundcover with flowers in orange, yellow, white, and magenta blooms may be single or double. Its leaves and stems are fleshy and succulent. Purslane is an excellent choice for containers and the front of a sunny border. Full sun and sandy soils are best, but purslane will grow in any garden soil that's not heavy clay. Deadheading will tidy up the plant but is not necessary for continuous bloom.

Even drought tolerant plants need a little extra water when they're getting established, so don't just plant and run. Water well, once a week, while your annuals are settling in then watch for signs of wilt as the summer progresses. Depending on where you live and how much rainfall you get, these annuals may need very little supplemental water for the rest of the season.

There are 32 states in Zone 5. States have more than one hardiness zone due to climate conditions and topography. For example, there are four zones in Wyoming.

Zone 5 States
Alaska California Colorado Connecticut
Idaho Illinois Indiana Iowa
Kansas Maine Maryland Massachusetts
Michigan Minnesota Missouri Montana
Nebraska Nevada New Hampshire New Mexico
New York Ohio Oregon Pennsylvania
South Dakota Utah Vermont Virginia
Washington West Virginia Wisconsin Wyoming

Winter Sowing Annuals

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Don't wait until spring to begin your garden, not even if you live where winter's deep cold and heavy snow cover seem to last forever. Many seeds of annual plants can be winter sown, and this process will give you a quick leap forward in your gardening endeavors well before the last frost leaves its mark. Starting seeds during the winter will also chase away those winter blahs, so it's a win-win situation for both you and your plants.

The pastel shades of springtime can be extended by a few weeks if seeds are winter sown. The seeds know better than we do as to when it's safe for them to sprout why wait until that time has passed to get them going? In the past I'd always waited too late to start seeds of my spring bloomers, and those plants invariably frizzled out prematurely. Here in the Midwest (zone 5b/6), we go from freezing cold to blazing hot seemingly overnight, so an early start is critical for those annuals that can't handle the heat. Some of the first annuals to bloom here are the clarkias, annual poppies, and violas, all of which do well when winter sown. As an added bonus, the violas, especially, seem to be much stronger plants than those started in a greenhouse and later shipped to a garden center. They bloom much further into the warm season than those pampered transplants, and most will bloom again in the cooler days of autumn.

Moldavian Dragon's Head, lavatera, and phacelia are also quick to bloom from winter sown seeds, and will soon follow the first of the spring bloomers to race out of the starting gate.

Winter sowing petunias was a shocking revelation for me! I'd always thought they were fussy and prissy plants that needed pampering in an indoor setting, but they absolutely love to grow in the cool winds and pounding rains of early spring.

Blue Pimpernel is one of my newest favorites for winter sowing. Blooms here appear in early June and continue throughout the baking heat of summer right up until the first killing freeze. Poor Man's Orchid (or Balfour's Touch Me Not) thrives when winter sown, and blooms in shade all summer long. Another long-blooming plant that acts as an annual here is Blackfoot Daisy, and another wonderful melampodium to winter sow is Star Daisy (Melampodium paludosum).

Now that you've got a visual of what can be, let's move right along into the breakdown of how it's done. It's really a very simple concept: You keep the seeds moist and safe from the worst of nature's elements and the mouths of hungry creatures until they've sprouted. That's it.

While there's likely to be as many ways to accomplish this as there are days in the week, today we'll highlight two methods that are tried and proven by many of our ATP members.

The first I tried is the repurposed jug method. This method works wonderfully for those folks who won't be up-potting their seedlings before planting out. You can up-pot them if you wish, of course, but if you run short on time they'll still have plenty of headroom to continue growing. Planting the entire mass of slightly older seedlings in one or two clumps is one of the favored methods of disbursement with this style of winter sowing. The drawbacks of this method are that it takes more prep time and it can be a bit difficult to prick out individual seedlings due to the interference of the jug itself.

The second method, one that I'm using now, is to sow seeds in vermiculite utilizing lidded, reusable containers. Re-usability is important to me, and since I generally up-pot all of my seedlings anyway, I'm opting for the space and time saving possibilities of this method this winter. I think it will allow me to get more seeds started this year than last. The one possible drawback that I can see is that there isn't as much vertical growing space available, so I'll have to check my containers for germination each day, once I see the first sprouts appear.

The joy of appreciating winter sown annuals continues into late summer with the bold and bright colors of Salvia coccinea, rudbeckia and Blanket Flower, to name a few.

As autumn and the end of gardening season approach, annual plants such as cosmos, cleome, snapdragon and a host of others carry the garden through until the first hard frosts appear.

Easy Annuals to Start from Seed

Start these outdoors, right in your garden where you want them to grow. This technique is often called "direct-sowing." There's little if any advantage planting them indoors. Most (except sweet peas, sweet alyssum, poppies and larkspur) are tender annuals and should not be sown until after danger of frost.

Morning glory
  • Sunflower
  • Marigold
  • Morning glory
  • Bachelor button
  • Calendula
  • Castor bean
  • Cosmos
  • Nasturtium
  • Sweet pea
  • Sweet alyssum
  • Larkspur
  • Annual poppy
  • Ammi majus
  • Zinnia
  • Hyacinth bean

Plant these seeds indoors, under lights, six to eight weeks before transplanting into the garden. Especially small seeds (including nicotiana, petunia and snapdragon) should be broadcast on a small seed tray. Once the seedlings have their first true leaves, carefully tease them apart and transplant into separate growing cells.

  • Cleome
  • Coleus
  • Snapdragon
  • Ageratum
  • Amaranth
  • Nicotiana
  • Lavatera
  • Petunia
  • Impatiens
  • Salvia
  • Statice

Sowing Seeds Yourself

Annuals that have self-seeded give your garden a natural look. However, sometimes they seed too enthusiastically or plant themselves where you wish they hadn't. Fortunately, self-sown annuals are easily transplanted to other spots in your garden or potted up for friends. Or you could take matters into your own hands and simply save the seeds and sow them yourself the following year instead of letting nature take care of the propagation. Then, either scatter the seeds directly into the flower bed or start the seeds indoors next spring.

If you choose to direct seed your own annual flowers, be sure you know and provide the conditions the seeds require to germinate, including:

  • Light: Some seeds need light to germinate and should not be covered with soil. Scatter these seeds and lightly press them into the soil with the back of a hoe or a board. Other annuals require darkness, which can be easily achieved with a top layer of soil.
  • Scarification: Several annual flowers protect their seeds with hard coverings. To improve the odds of these seeds germinating, scarify, or nick, the outer covering by rubbing with sandpaper or chipping the coating with a sharp knife. Use caution with the knife method. These seeds are hard and tiny, and it's so easy to miss. It's easier to soften the seed by soaking it overnight.
  • Cold: Besides moisture, some annual flower seeds, such as poppies, require a period of cold before they are triggered to begin germination. Nature takes care of this for us when the seeds are left on the ground during winter. If you are starting seeds indoors, place the potted seed in the refrigerator in a baggie for the recommended amount of time or in the garage, depending on the temperature. This is called stratification.

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