Nasturtium seeds germinate quickly in Ohio’s warming soil, but timing matters to avoid late frost damage. The best time to start nasturtium seeds in ohio is typically between mid-April and early May, depending on your specific region within the state. These vibrant flowers and edible leaves thrive when soil temperatures reach 60°F to 70°F, so waiting for consistent warmth is key.
Ohio’s climate can be tricky, with frost dates varying from late April in the south to mid-May in the north. You want to plant after the last expected frost, which for most of Ohio falls around May 10 to May 20. Starting seeds indoors gives you a head start, but direct sowing works well too if you time it right.
Nasturtiums are forgiving plants, but they dislike cold soil. If you plant too early, seeds may rot or fail to sprout. If you plant too late, you shorten the growing season and miss peak blooms. Let’s break down exactly when and how to start these seeds for the best results in Ohio.
Best Time To Start Nasturtium Seeds In Ohio
The ideal window for starting nasturtium seeds in Ohio is from April 15 to May 15. This range accounts for the state’s varied microclimates, from the warmer southern counties near the Ohio River to the cooler northern areas along Lake Erie. For central Ohio, including Columbus, aim for late April to early May.
Check your local frost dates using Ohio State University Extension resources or the Old Farmer’s Almanac. The last frost date in southern Ohio is around April 20, while northern Ohio often sees frost until May 15. Add two weeks after that date for safe soil warming.
Soil temperature matters more than calendar dates. Use a soil thermometer to check at a 2-inch depth. When it reads 60°F consistently for three days, you are good to go. Nasturtiums germinate best between 65°F and 70°F, so waiting for warmer soil speeds up sprouting.
Starting Nasturtium Seeds Indoors In Ohio
Starting seeds indoors gives you more control over temperature and moisture. Begin 2 to 4 weeks before your last frost date. For most of Ohio, that means starting indoors around April 1 to April 15.
Use biodegradable pots or seed trays with drainage holes. Nasturtiums have delicate taproots that dislike disturbance, so avoid plastic pots that require transplanting. Peat pots or paper cups work well because you can plant the whole container.
Follow these steps for indoor starting:
- Fill pots with seed-starting mix, not garden soil.
- Plant seeds 1/2 inch deep, one per pot.
- Water gently until the mix is moist but not soggy.
- Place pots in a warm spot, around 70°F to 75°F.
- Cover with plastic wrap or a humidity dome to retain moisture.
- Remove cover once seedlings appear, usually in 7 to 10 days.
- Move pots to a sunny windowsill or under grow lights for 12 to 14 hours daily.
- Harden off seedlings by setting them outside for a few hours each day, starting one week before transplanting.
Transplant seedlings outdoors after the last frost and when soil is warm. Space them 8 to 12 inches apart in full sun or partial shade. Water well after planting to reduce transplant shock.
Direct Sowing Nasturtium Seeds Outdoors In Ohio
Direct sowing is the simplest method for nasturtiums. Wait until soil temperatures reach 60°F, which in Ohio typically happens from late April to mid-May. For northern Ohio, this may be as late as May 20.
Prepare the planting bed by loosening soil to 6 inches deep. Nasturtiums prefer poor to average soil; too much fertilizer leads to more leaves and fewer flowers. Add compost only if your soil is very sandy or heavy clay.
Here is how to direct sow:
- Soak seeds in water overnight to soften the hard seed coat.
- Plant seeds 1/2 to 1 inch deep.
- Space seeds 8 to 12 inches apart for bush varieties, 12 to 24 inches for trailing types.
- Water gently after planting.
- Keep soil consistently moist until seedlings emerge, usually in 10 to 14 days.
- Thin seedlings to the strongest one per spot once they have two sets of true leaves.
Direct sowing works best for Ohio gardeners who want low-maintenance plants. Nasturtiums self-seed readily, so you may see volunteers next year if you let some flowers go to seed.
Ohio Frost Dates And Nasturtium Timing
Ohio spans USDA hardiness zones 5a to 6b, with frost dates varying by location. Knowing your zone helps you pinpoint the best time to start nasturtium seeds. Here is a breakdown by region:
- Southern Ohio (Cincinnati, Dayton, Portsmouth): Last frost around April 10 to April 20. Start seeds indoors March 20 to April 1. Direct sow April 20 to May 1.
- Central Ohio (Columbus, Newark, Chillicothe): Last frost around April 25 to May 5. Start seeds indoors April 1 to April 15. Direct sow May 1 to May 15.
- Northern Ohio (Cleveland, Toledo, Akron): Last frost around May 5 to May 15. Start seeds indoors April 15 to April 25. Direct sow May 15 to May 25.
- Lake Erie Shore (Sandusky, Port Clinton): Last frost around May 10 to May 20. Start seeds indoors April 20 to April 30. Direct sow May 20 to June 1.
These dates are averages. Check your local weather forecast in spring for unexpected cold snaps. If a late frost is predicted, cover young plants with row covers or old bedsheets overnight.
Soil Preparation For Nasturtiums In Ohio
Nasturtiums are not fussy about soil, but they do need good drainage. Ohio’s clay soils can hold too much moisture, leading to root rot. Amend heavy clay with sand or perlite to improve drainage.
Test your soil pH if you want optimal growth. Nasturtiums prefer a pH between 6.0 and 7.5. Ohio soils are often slightly acidic, so adding lime may help if your pH is below 6.0.
Avoid high-nitrogen fertilizers. They encourage lush foliage at the expense of flowers. Instead, use a balanced fertilizer like 5-10-10 or no fertilizer at all if your soil is moderately fertile.
For containers, use a well-draining potting mix. Nasturtiums grow well in pots, window boxes, and hanging baskets. Ensure containers have drainage holes to prevent waterlogging.
Common Mistakes When Starting Nasturtium Seeds In Ohio
Many Ohio gardeners make a few predictable errors. Here are the most common ones and how to avoid them:
- Planting too early: Cold soil causes seeds to rot. Wait until soil is at least 60°F.
- Overwatering: Nasturtiums prefer slightly dry conditions. Water only when the top inch of soil feels dry.
- Too much shade: These plants need at least 6 hours of direct sun daily for best blooms.
- Rich soil: Fertile soil leads to lots of leaves and few flowers. Plant in average or poor soil.
- Ignoring pests: Aphids love nasturtiums. Spray them off with water or use insecticidal soap.
Another mistake is not hardening off indoor-started seedlings. Sudden exposure to sun and wind can shock or kill young plants. Always acclimate them over 5 to 7 days.
Growing Nasturtiums Through Ohio’s Summer
Once established, nasturtiums are drought-tolerant and low-maintenance. Ohio summers can be hot and humid, but these plants handle it well if they have some afternoon shade in southern regions.
Water deeply once a week during dry spells. Mulch around plants to retain moisture and keep roots cool. Deadhead spent flowers to encourage continuous blooming from June through October.
Nasturtiums are edible, with peppery flowers and leaves. Harvest them in the morning for the best flavor. Use them in salads, as garnishes, or infused in vinegar. Avoid using pesticides if you plan to eat them.
In late summer, allow some flowers to go to seed. Collect the seeds once they turn brown and fall off easily. Store them in a cool, dry place for next year’s planting.
Varieties Of Nasturtiums For Ohio Gardens
Choose varieties that suit your space and goals. Bush types are compact and ideal for borders or containers. Trailing types spill over edges and work well in hanging baskets.
Popular varieties for Ohio include:
- Jewel Mix: Compact bush type with bright flowers in red, orange, and yellow.
- Empress of India: Deep crimson flowers and blue-green leaves, great for containers.
- Alaska Mix: Variegated leaves with cream edges, plus colorful blooms.
- Moonlight: Pale yellow trailing type, perfect for hanging baskets.
- Peach Melba: Soft peach flowers with red centers, good for edging.
All these varieties grow well in Ohio’s climate. They bloom from early summer until the first fall frost, which in Ohio is typically late October to early November.
Extending The Growing Season For Nasturtiums In Ohio
You can get a head start by using season extenders. Cold frames or cloches protect young plants from light frosts, allowing you to plant 2 to 3 weeks earlier. Row covers also help warm the soil and shield plants from wind.
For a fall harvest, plant a second batch of seeds in late July or early August. These plants will bloom until the first hard frost. In southern Ohio, you may get blooms into November.
If you grow nasturtiums in containers, you can move them indoors before frost. Place them in a sunny window and treat them as houseplants. They will continue blooming for weeks indoors.
Frequently Asked Questions
Can I start nasturtium seeds in Ohio in March?
March is too early for outdoor planting in Ohio. Soil is still cold, and frost is common. Start seeds indoors in late March for transplanting in May, but do not direct sow until April or May.
What is the best time to start nasturtium seeds in Ohio for fall blooms?
For fall blooms, sow seeds directly in late July or early August. This gives plants time to mature before the first frost in October or November. Water regularly during hot August weather.
Should I soak nasturtium seeds before planting in Ohio?
Yes, soaking seeds overnight in warm water softens the hard seed coat and speeds germination. This is especially helpful in Ohio’s variable spring weather, where quick sprouting reduces rot risk.
How deep should I plant nasturtium seeds in Ohio soil?
Plant seeds 1/2 to 1 inch deep. In heavy clay soil, plant shallower to prevent waterlogging. In sandy soil, plant slightly deeper to maintain moisture around the seed.
Can nasturtiums survive Ohio’s hot summers?
Yes, nasturtiums tolerate heat well, especially if they get afternoon shade. Water deeply during dry spells. Mulch helps keep roots cool. Some varieties may pause blooming in extreme heat but resume in late summer.
Final Tips For Ohio Nasturtium Growers
Timing is everything when starting nasturtium seeds in Ohio. Pay attention to your local frost dates and soil temperature. A little patience in spring pays off with months of colorful blooms and edible leaves.
Remember that nasturtiums thrive on neglect. Do not overwater or overfertilize. Let them grow in average soil with full sun, and they will reward you with abundant flowers from June until frost.
If you miss the spring window, you can still plant in early summer. Seeds sown in June will bloom by August and continue until frost. Just keep them watered during establishment.
Nasturtiums are also great companion plants in vegetable gardens. They repel aphids and other pests from tomatoes, cucumbers, and squash. Plant them near your veggies for natural pest control.
Collect seeds from your healthiest plants each year. Over time, you will develop strains adapted to your specific Ohio microclimate. This saves money and ensures reliable germination.
With the right timing and care, nasturtiums are one of the easiest and most rewarding flowers to grow in Ohio. Start them at the best time, and enjoy their beauty and utility all season long.