Zone Pushing, Montana Edition

What is Zone Pushing?

Zone pushing is the gardening practice of growing a plant outside its recommended USDA hardiness zone. A "tender perennial" is a plant that is perennial (comes back year after year) in warm climates but is not winter-hardy in your colder zone.

Zone pushing is about creatively helping these plants survive winter so you can enjoy them for multiple seasons.

Our Fall Tender Perennial Display (Montana)

“Zone pushing is about creatively helping these plants survive winter so you can enjoy them for multiple seasons.”

A Short Guide to Zone Pushing Tender Perennials:

It's part experimentation, part optimism, and all reward!

Step 1: Know Your Zone & Their Zone

· Your Zone: First, know your exact USDA Hardiness Zone. This is based on your average annual extreme minimum temperature.

· Their Zone: Check the plant's label or description. If you are in Zone 4, a plant rated for Zone 5 is a good candidate for pushing. A plant from Zone 8 or 9 is a much bigger, but sometimes possible, challenge.

Step 2: Choose the Right Candidates

Not all tender perennials are equally pushable. Good choices often have these traits:

· Woody Stems: Plants like Lantana, Rosemary, Mexican Bush Sage.

· Dense Crowns: Plants like Canna Lilies, Dahlia (tubers), Agapanthus.

· Strong Will to Live: Some plants just seem determined. Salvia greggii, Pennisetum 'Fireworks', and Chinese Hibiscus can often be pushed.

· Avoid: succulent type plants or those extremely prone to rot (e.g., some Begonias) are trickier.

The Three Main Strategies

You can use one or a combination of these methods.

1. The Cozy Blanket (Heavy Mulching)

· Best for: Plants with a hardy crown or base, slightly borderline (e.g., Zone 7 plant in Zone 6).

· How-To: After the first hard frost kills the foliage, cut the plant back to 4-6 inches. Pile a thick, fluffy, dry mulch (like straw, shredded leaves, or pine boughs) at least 12 inches deep over the crown. The goal is to keep the soil consistently frozen, preventing damaging freeze-thaw cycles.

· Remove the mulch gradually in spring after the danger of hard frost has passed.

2. The "Lift & Store" Method (Overwintering Indoors)

· Best for: Plants with tubers, rhizomes, or bulbs (Dahlias, Cannas, Gladiolus, Elephant Ears).

· How-To: After frost blackens the foliage, carefully dig up the root structure.

· Gently brush off soil, cut stems to an inch, and let them cure (dry out) for a day or two.

· Store them in a cool (40-50°F / 4-10°C), dark, and dry place for winter. Pack them in a box or paper bag filled with slightly moist peat moss, vermiculite, or sawdust.

· Replant outdoors after your last spring frost.

3. The Sunny Window (Bringing Pots Inside)

· Best for: Any tender perennial you've grown in a container.

· How-To: Before your first frost, bring the pot indoors.

· Option A (Dormancy): Place the pot in a cool, dark place like a basement or garage (ideally 35-50°F / 2-10°C). Water just enough every few weeks to keep the roots from completely drying out. The plant will go dormant and drop leaves.

· Option B (Houseplant): Place it in a sunny window and water as needed. It may continue to grow slowly. Be sure to check for pests like aphids or spider mites first.

Pro-Tips for Success:

Patience in Spring

· Don't be too quick to declare failure! Tender perennials are often the last to wake up in spring. Wait until the soil is truly warm before you dig up a spot to check for signs of life.

· For mulched plants, wait until new growth appears from the base before fertilizing.

Location is Key:

Plant tender perennials in a sheltered microclimate—against a warm south-facing wall, near a foundation, or in a courtyard. These spots can be a full zone warmer than the middle of your yard.

· Well-Drained Soil is Non-Negotiable: Wet, cold soil kills roots. Ensure your planting bed has excellent drainage. Raised beds are perfect for zone pushing.

· Let Them Harden Off: In fall, allow the plant to experience a few light frosts. This signals it to go dormant and helps harden off tissues for winter.

· Experiment & Keep Notes: Zone pushing isn't a guarantee. Consider every plant that comes back a victory and every loss a learning experience. Keep a garden journal to track what works and what doesn't in your specific garden.

Remember: The worst that can happen is you have to buy a new plant next year. The best that can happen is you get to enjoy a unique, mature, and thriving plant that none of your neighbors have!

Happy Gardening!

-Tali