Michigan’s variable spring weather makes late May the safest bet for nasturtium, as the soil warms and the risk of a late freeze diminishes. Knowing the best time to plant nasturtium in michigan is key to getting those bright blooms and peppery leaves all summer. You want to avoid the cold snaps that can kill tender seedlings or rot seeds in the ground.
Nasturtiums are not frost-hardy plants. They need warmth to germinate and thrive. In Michigan, you are working with USDA zones 4 through 6, which means a short growing season in the north and a longer one down south. The trick is to wait for the right soil temperature and weather pattern.
This guide covers everything from soil temps to indoor starting tips. You will learn exactly when to put seeds in the ground or transplant seedlings. Let’s get your nasturtiums growing strong.
Best Time To Plant Nasturtium In Michigan
The best time to plant nasturtium in michigan is after the last frost date for your specific area. For most of the Lower Peninsula, that falls between mid-May and early June. In the Upper Peninsula, you may need to wait until late May or even early June.
Soil temperature matters just as much as the calendar date. Nasturtium seeds germinate best when the soil is at least 60°F (15°C). Cold, wet soil will cause seeds to rot before they sprout. Use a soil thermometer to check the temperature at a depth of two inches.
Here is a simple breakdown by region:
- Southern Michigan (Zone 6): Plant seeds outdoors from late April to mid-May. Watch for late frost warnings.
- Central Michigan (Zone 5): Aim for mid-May to late May. Soil warms up slower here.
- Northern Michigan and Upper Peninsula (Zone 4): Wait until late May or early June. Cold nights are common into June.
If you want an earlier start, you can sow seeds indoors about four weeks before your last frost date. Use biodegradable pots to avoid disturbing the roots when transplanting. Nasturtiums have delicate root systems that do not like being moved.
Checking Your Local Frost Dates
Your exact planting window depends on your zip code. The average last frost date in Detroit is around April 20. In Traverse City, it is closer to May 15. In Marquette, you might see frost into early June.
Check the Old Farmer’s Almanac or your local extension office for precise dates. Do not rely on a single date. Watch the weather forecast for a stretch of warm nights above 50°F.
If a late frost is predicted after you have planted, cover your seedlings with a row cover or a cloche overnight. Remove it in the morning so the plants get sun and air.
Soil Preparation Tips
Nasturtiums actually prefer poor soil. Rich, fertile soil leads to lots of leaves but few flowers. Sandy or loamy soil with good drainage works best. Avoid heavy clay that stays wet.
Before planting, loosen the soil to about six inches deep. Mix in a little compost if your soil is very sandy or compacted. Do not add nitrogen-rich fertilizer. That will give you giant leaves and almost no blooms.
Test the soil pH if you can. Nasturtiums like a pH between 6.0 and 7.5. Most Michigan soil falls in this range naturally. If your soil is very acidic, add a little lime in the fall before planting.
Starting Nasturtiums Indoors In Michigan
Starting seeds indoors gives you a head start, especially in northern Michigan. You can plant seeds in early April for a May transplant. Use peat pots or paper cups to minimize root disturbance.
Fill pots with seed-starting mix. Plant one seed per pot, about half an inch deep. Water gently and keep the soil moist but not soggy. Place pots in a warm spot, around 65-70°F.
Seeds should sprout in 7 to 14 days. Once they have two true leaves, move them to a sunny windowsill or under grow lights. Keep them indoors until the soil outside is warm enough.
Hardening Off Seedlings
You cannot just move indoor seedlings straight into the garden. They need to adjust to outdoor conditions slowly. This process is called hardening off.
Start about a week before transplanting. Place the pots outside in a shaded, sheltered spot for a few hours each day. Gradually increase the time and sunlight exposure over the week.
Bring them indoors at night if temperatures drop below 50°F. After a week, they are ready to stay out overnight if the weather is mild. Then you can transplant them into the garden.
Transplanting Tips
Choose a cloudy day or late afternoon for transplanting. This reduces transplant shock. Dig a hole slightly larger than the pot. Place the whole pot in the ground if it is biodegradable. Tear off the rim so it does not wick moisture away.
Water the seedlings well after planting. Space them about 10 to 12 inches apart for bush varieties. Trailing types need more space, about 18 inches apart. Nasturtiums spread quickly once they settle in.
Do not fertilize after transplanting. They do not need extra food. Just water them regularly until they establish new roots. After that, they are quite drought-tolerant.
Direct Sowing Nasturtium Seeds In Michigan
Direct sowing is the easiest method for most Michigan gardeners. You skip the indoor step and plant seeds right where you want them to grow. This works well for nasturtiums because they dislike being moved.
Wait until the soil temperature is consistently above 60°F. In southern Michigan, that is usually by early May. In the north, you may need to wait until late May or early June. Use a soil thermometer to be sure.
Soak the seeds in water overnight before planting. This softens the hard seed coat and speeds up germination. Plant seeds about half an inch deep and six inches apart. Cover them lightly with soil and water gently.
Seeds will germinate in 7 to 14 days, depending on soil temperature. Keep the soil moist but not waterlogged during this time. Once seedlings appear, thin them to 10 to 12 inches apart for bush types.
Dealing With Michigan’s Late Frosts
Even after the last average frost date, a surprise cold snap can happen. Michigan weather is unpredictable. If frost is forecast after you have direct-sown seeds, cover the area with a floating row cover or an old sheet.
Remove the cover in the morning when temperatures rise above freezing. Frost cloth lets light and air in while protecting the seeds. If seeds have not sprouted yet, they are usually safe underground. But emerging seedlings are vulnerable.
If you are worried about frost, wait an extra week. A late planting still gives you plenty of time for flowers and seed pods before fall. Nasturtiums bloom from summer until the first hard frost in autumn.
Succession Planting For Continuous Blooms
You can plant nasturtiums in waves for a longer bloom period. Sow a batch in late May, then another batch in mid-June. This staggers the flowering so you have fresh blooms all summer.
Succession planting works well in Michigan because the growing season is long enough. Just make sure the second batch has at least 60 days before your first fall frost. In most of Michigan, that means planting by early August.
If you plant too late, the plants may not have time to flower before frost. Check your local first frost date. In southern Michigan, that is usually mid-October. In the north, it can be as early as late September.
Choosing The Right Nasturtium Varieties For Michigan
Some nasturtium varieties perform better in Michigan’s climate than others. Dwarf or bush types are great for small spaces and containers. Trailing types work well in hanging baskets or as ground cover.
Popular varieties for Michigan include:
- Alaska Mix: Variegated leaves and bright flowers. Good for cooler summers.
- Jewel Mix: Compact plants with double flowers. Blooms early and long.
- Empress of India: Deep red flowers and blue-green leaves. Tolerates some shade.
- Moonlight: Pale yellow trailing flowers. Excellent for hanging baskets.
- Peach Melba: Creamy yellow with red centers. Very heat-tolerant.
All these varieties are easy to grow from seed. They bloom within 60 to 70 days from planting. Choose based on your space and color preference. Mixing varieties adds visual interest.
Where To Plant Nasturtiums In Your Garden
Nasturtiums need full sun for the best flowering. In Michigan, that means at least six hours of direct sunlight per day. They can tolerate partial shade, but you will get fewer blooms and more leaves.
They grow well in garden beds, borders, and containers. Use them as a colorful ground cover or let them trail over walls. They also make excellent companion plants for vegetables like tomatoes and cucumbers.
Nasturtiums repel some pests like aphids and whiteflies. Plant them near your vegetable garden for natural pest control. They also attract beneficial insects like bees and butterflies.
Watering And Care During Michigan Summers
Nasturtiums are drought-tolerant once established. But they need regular watering during dry spells. Water deeply once a week if there is no rain. In containers, water more often because pots dry out faster.
Do not overwater. Soggy soil leads to root rot and fungal diseases. Let the top inch of soil dry out between waterings. Mulching around the plants helps retain moisture and keeps roots cool.
Deadhead spent flowers to encourage more blooms. You can also harvest the flowers and leaves for salads. They have a peppery, radish-like flavor. The seed pods can be pickled like capers.
Common Problems With Nasturtiums In Michigan
Nasturtiums are generally pest-free, but a few issues can arise. Aphids sometimes attack the undersides of leaves. A strong spray of water knocks them off. You can also use insecticidal soap if needed.
Slugs and snails love nasturtiums, especially in wet weather. Handpick them at night or use beer traps. Diatomaceous earth around the plants also helps deter them.
Powdery mildew can appear in humid conditions. Space plants well for air circulation. Avoid overhead watering. If mildew appears, remove affected leaves and treat with a baking soda solution.
Harvesting Nasturtium Seeds For Next Year
You can save seeds from your nasturtiums for planting next season. Let some flowers go to seed. The seed pods will turn brown and fall off when ripe. Collect them before they drop to the ground.
Dry the seeds in a single layer for a week or two. Store them in a paper envelope in a cool, dry place. Nasturtium seeds remain viable for about three to five years. Label the envelope with the variety and year.
Saving seeds is a great way to grow your favorite varieties year after year. It also saves money. Just make sure the seeds are fully dry before storing to prevent mold.
Frequently Asked Questions
Can I plant nasturtiums in Michigan in July?
Yes, you can plant in July, but you may have a shorter bloom period. Choose early-flowering varieties and plant by mid-July. You should get flowers before the first frost in October.
Do nasturtiums come back every year in Michigan?
No, nasturtiums are annuals in Michigan. They die with the first hard frost. However, they often self-seed if you let some flowers go to seed. New plants may appear the next spring.
Should I soak nasturtium seeds before planting?
Soaking seeds overnight in warm water helps soften the hard seed coat. This speeds up germination by a few days. It is not required, but it is recommended for Michigan’s short growing season.
Can I grow nasturtiums in containers in Michigan?
Absolutely. Nasturtiums thrive in containers. Use a pot with drainage holes and a quality potting mix. Water more often than garden plants. Trailing varieties look great in hanging baskets.
What is the best soil for nasturtiums in Michigan?
Poor to average soil with good drainage is best. Avoid rich, fertile soil that promotes leaf growth over flowers. Sandy or loamy soil works well. Add compost only if your soil is very poor.
Final Tips For Success
Planting nasturtiums at the right time in Michigan is simple once you understand your local climate. Wait for warm soil and no frost risk. Start seeds indoors if you want an early start. Direct sow for the easiest method.
Give them full sun and poor soil. Water sparingly and deadhead regularly. They will reward you with months of colorful blooms and edible leaves. Nasturtiums are one of the easiest flowers to grow in Michigan.
Remember that the best time to plant nasturtium in michigan is after the last frost, when the soil is warm. Check your local frost dates and soil temperature. With a little planning, you will have a beautiful display all summer long.
Enjoy your gardening. Nasturtiums are forgiving plants that even beginners can grow successfully. Just avoid planting too early, and you will be fine.