When it comes to gardening in Southern Michigan, timing is everything—especially when it comes to planting perennials and shrubs. The timing depends on the weather and soil. Southern Michigan has cold winters and warm summers, with frost in early October and late April.
To help plants grow strong roots, the soil should stay above 50°F for at least 6-8 weeks before it freezes. Fall is usually the best time to plant perennials and shrubs in Southern Michigan, with higher survival rates compared to spring.
The Great Lakes make the weather milder, extend the growing season, and increase spring rain. Soil warms up by mid-April and cools by mid-October, so plan planting around these times for the best results.
This guide will help you discover the best time to plant perennials and shrubs in Southern Michigan, with tips tailored to its unique climate and soil conditions, so your garden can flourish year-round.
Understanding Southern Michigan’s Climate
In Southern Michigan, winters can get very cold, with temperatures as low as -15°F. The area has four seasons and a growing season of 150-170 days. It gets 30-35 inches of rain each year. Spring starts cold, with temperatures from 35°F in March to 65°F in May. By mid-April, the soil warms to 50°F, which is good for planting. Summers are warm, with temperatures between 70-85°F, sometimes going over 90°F.
Fall cools down, with temperatures dropping from 65°F in September to 50°F in November. Frost usually comes in early October, and the last frost of spring is between May 1-15. In winter, the soil gets cold, and frost goes 15-20 inches deep. Plants grow best when the soil stays above 55°F, which usually happens a few weeks after the air warms up.
Best Time to Plant Perennials and Shrubs in Southern Michigan
The best times to plant perennials and shrubs in Southern Michigan are early spring (mid-April to June) and early fall (late August to October). Fall planting is better because it has more rain, cooler temps, and 6-8 weeks for roots to grow before winter. Spring planting works too but needs more watering due to heat and drought risks.
The Best Time to Plant Perennials in Southern Michigan
The optimal time to plant perennials in Southern Michigan is during early fall, between August 15 and September 30. This period is considered ideal due to the perfect growing conditions that support root development, with a high success rate of 80-90%.
The cooler temperatures and ample time before the first frost provide an excellent opportunity for plants to establish strong roots, ensuring their survival through the winter months.
Fall Planting: Ideal Conditions for Perennials
In fall, the soil temperature typically ranges from 65-75°F, which is perfect for encouraging root growth. During this period, the region receives around 3-3.5 inches of rainfall per month, offering sufficient moisture for new plantings.
With 6-8 weeks before the first frost, plants have ample time to establish their roots, significantly enhancing their chances of survival. Additionally, fall planting requires 40% less watering compared to spring planting, making it a more water-efficient option.
Spring Planting: The Second-Best Option
While early spring, from April 15 to May 30, is the second-best time to plant perennials, it still provides a solid success rate of 70-80%. However, the soil must be above 50°F and should not be too wet for planting.
The best time to plant in spring is after the last frost date, which typically falls between May 1 and May 15. Although spring planting has a slightly lower success rate than fall planting, it remains a viable option for many types of perennials.
Best Perennials for Fall and Spring Planting
Fall planting is perfect for early bloomers and deep-rooted plants, including peonies, iris, daylilies, baptisia, butterfly weed, and Russian sage. These plants establish strong roots before the colder months.
On the other hand, spring planting is best for late-season bloomers and tender perennials like chrysanthemums, black-eyed Susans, lavender, hibiscus, and coreopsis, which flourish as the weather warms.
The Best Time to Plant Shrubs in Southern Michigan
In Southern Michigan, the best time to plant shrubs is similar to planting perennials, but shrubs need more time to grow their roots.
Spring Planting for Tender Shrubs
Spring (mid-April to early June) is best for tender shrubs like hydrangeas and butterfly bushes. Make sure the soil has good drainage and includes organic matter.
Fall Planting for Hardy Shrubs
Fall (late August to early October) is ideal for hardy shrubs like viburnum and dogwood. Planting in fall gives shrubs enough time to develop roots before winter.
Watering Needs and Mulch for Protection
Spring-planted shrubs need 30-40% more water. Fall-planted shrubs do better with natural rain, but you should add 3-4 inches of mulch to protect them from winter cold.
Differences from Perennials
Shrubs need deeper soil (18-24 inches) than perennials (12-15 inches). They also take longer to establish roots—about 10-12 weeks compared to 6-8 weeks for perennials. Timing is more important for shrubs to ensure they establish before the ground freezes.
Preparing for Planting Perennials and Shrubs in Southern Michigan
Site Preparation
To get the best results, test your soil before planting. Ideal pH levels are between 6.0 and 7.0, but some areas in southeast Michigan have a soil pH higher than 7.0.
The goal is to have 5-7% organic matter. For soil testing, check the depth: 6-8 inches for perennials and 12-18 inches for shrubs.
Drainage is also important. Soil should drain 1-2 inches per hour. To test, dig a hole, fill it with water, and see how long it takes to drain. If water sits for more than 24 hours, drainage is poor.
Planting Process
When planting, make sure the hole is the right size:
For perennials, the hole should be twice the width of the root ball and the same depth. Space them 12-24 inches apart.
For shrubs, the hole should be three times the width of the root ball and the same depth as the root height. Space shrubs 3-6 feet apart, depending on their spread.
Mix your soil with organic matter. For clay soil, add 2-3 inches of compost. For sandy soil, add 3-4 inches.
Planting Steps
Before planting, soak the roots for 1-2 hours. Trim any damaged roots, but no more than 10-15%. This can increase success rates by 25-30%.
When planting, the crown (top of the roots) should be at soil level, and the root flare (where roots spread out) should be 1-2 inches above the ground. This can reduce plant death by 40-50%.
After planting, water the plants with 1-2 inches of water each week. Add 2-3 inches of mulch to help with moisture and temperature control. Perennials take 4-6 weeks to establish, while shrubs need 8-12 weeks.
Post-Planting Care
In the first month, water your plants every 2-3 days. In the second month, water weekly. Once established, water bi-weekly. This increases success rates by 80%.
Mulching helps a lot:
It keeps moisture in (+40%).
It reduces weeds by 70-80%.
It keeps temperatures steady (+/-10°F).
It protects roots, improving survival rates to 85%.
Monitor your plants regularly:
Check leaves for health every week.
Measure growth monthly.
Look for new growth 2-4 weeks after planting and check for firmness in leaves daily early on.
Never Miss: Pamacrystial Plant Care
Southern Michigan Gardening Tips
Weather Adaptation
In Southern Michigan, spring frost can happen until May 15, with a 30% chance. The temperature can change by ±20°F in just 24 hours. To protect plants:
Use frost blankets, which raise the temperature by 4-6°F.
Use cold frames, which keep plants 10-15°F warmer. These methods increase success rates by 85-90%.
Watering Guidelines
In spring (April-June):
Water new plants 1-1.5 inches weekly.
Water established plants 1 inch weekly.
Watering in the morning is more effective (90% success) than in the afternoon (60% success).
Keep soil moisture at 40-60%.
In Fall (September-November):
Water new plants 1 inch weekly until it freezes.
Start reducing watering in late October.
Give plants a final deep watering in early November. This helps root establishment with a success rate of 75-85%.
Winter Protection
Mulching helps protect plants in winter:
Apply mulch 2-3 inches deep after the ground freezes.
Shredded bark has the best success (85%).
Straw works well (80% success), and leaves are also good (75% success).
Mulch can protect plants by ±10°F. Snow adds about 20°F of extra protection. Plants that are properly mulched have a survival rate of 90-95%, compared to 60-70% for unmulched plants.
Other ways to protect plants:
Use anti-desiccant sprays for 30% better survival.
Wind barriers can reduce damage by 40%.
Planting plants close together can increase survival by 25%.
Common Mistakes to Avoid When Planting Perennials and Shrubs in Southern Michigan
Climate and Timing Mistakes
Planting Too Early
Frost can still happen until May 10 in most areas.
Soil needs to be at least 50°F for planting.
Planting too early can lead to 43% more plant deaths.
Ignoring Hardiness Zones
Southern Michigan is in zones 5b-6a, where temperatures can drop to -15°F.
Using plants that aren’t hardy for your zone leads to 37% of failures.
Local areas can be warmer or colder by about 5°F, so check your location.
Soil-Related Mistakes
Skipping Soil Testing
Many gardens in Michigan lack nutrients.
Most perennials need soil pH between 6.0-7.0.
Shrubs like blueberries need more acidic soil (pH 4.5-6.0).
Adding phosphorus and organic matter improves soil health.
Not Preparing the Soil
Perennials need soil at least 12-18 inches deep.
Shrubs require even deeper soil, around 24-36 inches.
Adding organic material can prevent root rot by 60%.
Planting Technique Errors
Planting Too Deep
The base of the plant, called the root flare, should be 1-2 inches above the soil.
Planting deeper reduces survival by 15% for every inch.
Crowding Plants Together
Leave enough space for plants to grow.
Small perennials: 12-18 inches apart.
Large perennials: 24-36 inches apart.
Small shrubs: 3-4 feet apart.
Large shrubs: 6-8 feet apart.
Overcrowding increases disease by 45%.
Post-Planting Care Mistakes
Watering Issues
Perennials need 1 inch of water weekly in the first year.
Shrubs need 2-3 inches of water weekly.
Water deeply instead of lightly to promote better root growth.
Mulching Errors
Use 2-3 inches of mulch, but keep it 3-4 inches away from the plant’s base.
Too much mulch causes root rot, pest problems, and poor water absorption.
Regional Tips
Use Native Plants
Native plants are more likely to survive.
They need 45% less water and support more pollinators.
Winter Protection
Use anti-desiccant sprays to prevent winter burn.
Add mulch to reduce frost damage and keep roots warm.
Best Planting Seasons
Spring Planting
Perennials: 75% success rate.
Shrubs: 65% success rate.
Needs more watering.
Fall Planting
Perennials: 85% success rate.
Shrubs: 80% success rate.
It requires 30% less watering.
Conclusion: Best Time to Plant Perennials and Shrubs in Southern Michigan
In conclusion, planting perennials and shrubs in Southern Michigan needs planning. The best times to plant are in spring and fall. This helps the plants grow strong roots. Make sure to prepare the soil, water well, and care for them regularly. With these simple steps, you can grow a beautiful garden that lasts all year. Happy gardening!
FAQs
What is the best time to plant Perennials and Shrubs in Southern Michigan?
The best time to plant perennials and shrubs in Southern Michigan is during the spring and fall when temperatures are mild and conducive to root establishment.
What month is best to plant perennials?
September to early October. This gives an 85% success rate and needs 30% less water than planting in spring.
When should you plant shrubs in Michigan?
Mid-September to mid-October. This time helps roots grow well before the frost, with an 80% success rate.
What is the best month to plant shrubs?
Mid-September. The soil is just right (55-60°F) for strong roots to grow before winter.
What is the most hardy perennial?
Daylilies (Hemerocallis). They survive winter, even in -40°F, and can handle droughts lasting 30 days.
What is the fastest-spreading perennial?
Creeping Jenny (Lysimachia nummularia). It spreads 24 inches a year and covers 6 square feet in one season.
What is the longest blooming perennial?
Black-eyed Susan ‘Goldsturm’. It blooms for 3-4 months (July-October) and keeps 85% of its flowers.
What is the easiest perennial to grow?
Hostas are great for beginners with a 95% success rate, 90% disease resistance, and needs little care—just 2-3 hours a year.
4 thoughts on “Best Time to Plant Perennials and Shrubs in Southern Michigan: A Comprehensive Guide”