When to Plant Catnip in Box Elder, Montana (59521)

Location

Box Elder, Montana

ZIP Code

59521

USDA Zone

Last Frost

Friday, May 15, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Friday, March 20, 2026

Transplant Outdoors

Friday, May 29, 2026

Based on last frost Friday, May 15, 2026 · Zone 4a

Pro tip: Start Catnip seeds indoors 8 weeks before your last frost date, then transplant outdoors around Friday, May 29, 2026.

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🌿 Plant Details

Scientific Name Nepeta cataria

Days to Maturity 90 days

Mature Height 18-36"

Spread 18"

☀️ Growing Requirements

☀️

Sun

Full Sun to Partial Shade

💧

Water

Low (less than 1 inch/week)

↔️

Spacing

18" apart

🌱

Planting Depth

0.125" deep

Seeds typically germinate in 7-14 days

Ready to Plant Catnip in Box Elder?

Get your seeds now so they're ready by Friday, March 20, 2026.

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🤝 Good Companions

TomatoPepperSquashPumpkin

🤝

Full Companion Planting Guide for Catnip

See which plants help Catnip thrive, which to keep away, and raised bed layout tips →

🛠️ Supplies You'll Need

🌱 Seed Starting Trays 🪴 Seed Starting Mix 💡 Grow Lights 🌡️ Heat Mat 🪵 Raised Garden Bed 🌍 Vegetable Garden Soil 🛠️ Hand Trowel Set 🚿 Watering Can

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🌾 Seed Saving Guide

🟢 Easy

✅ Open-pollinated — seeds grow true to parent

When to Harvest Seed

Let flower spikes dry completely on the plant. Seeds form in small nutlets inside dried calyxes.

Processing

Strip dried stems over a bowl, rub between fingers to release seeds, winnow lightly.

Seed Viability

Up to 3 years when stored cool, dark, and dry.

Pro Tip

Catnip self-sows freely and can become weedy — deadhead most plants to control spread.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 14 plants of Catnip. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Catnip in Box Elder, Montana? +

In Box Elder (Zone 4a), start Catnip seeds indoors around Friday, March 20, 2026 and transplant outdoors around Friday, May 29, 2026.

What is the last frost date for Box Elder, Montana? +

The average last spring frost date for Box Elder, Montana (ZIP 59521) is around Friday, May 15, 2026. This is based on NOAA climate normals for USDA Zone 4a.

How long does Catnip take to grow? +

Catnip typically matures in about 90 days from transplanting. In Box Elder, that means you can expect harvest around Friday, May 29, 2026 plus 90 days.

Should I start Catnip indoors or direct sow in Montana? +

Catnip should be started indoors 8 weeks before your last frost date. In Box Elder, that means starting around Friday, March 20, 2026.

📚 More Catnip Planting Guides

🗺️

Catnip in Montana

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 4a Catnip Guide

All cities in your zone · Avg dates

→

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Growing Catnip in Zone 4a

Catnip (Nepeta cataria) is a popular garden vegetable. In Box Elder, Montana, which is in USDA Hardiness Zone 4a, you should start seeds indoors around Friday, March 20, 2026.

Your average last frost date is Friday, May 15, 2026. Plan to transplant your Catnip seedlings outdoors around Friday, May 29, 2026, about 2 weeks after your last frost date.