If you have been wondering when to start marigold seeds indoors, you are in the right place! The best time to plant your marigold seeds is 6 to 8 weeks before your area’s last expected frost date. This gives the seedlings enough time to grow to a good size and ready to be planted out when the weather is finally warm enough for transplanting.
Read on for more details about starting marigolds from seed indoors, and transplanting the seedlings into the garden!
Getting Started
Marigolds are hardy, sun-loving annual flowers known for their bright colors, low maintenance, and versatility in gardens. They are easy to grow, and very popular summer flowers!
The plants belong to the Tagetes genus and are native to Mexico and Central America, but they have become popular worldwide for their beauty and low maintenance nature.
Marigolds are easily started from seed, and can be either directly sown outdoors into your containers or garden, or started earlier indoors. Starting your marigold seeds earlier indoors is a great way to get a head start on the growing season, especially if you live in a cooler climate.
Why Start Marigold Seeds Indoors?
Starting marigolds indoors offers several advantages:
- While marigolds are hardy and easy to grow, beginning them indoors from seeds gives you greater control and ensures earlier, healthier blooms.
- This is especially helpful in cooler climates with shorter growing seasons.
- Starting the seeds indoors allows you to plant them before outdoor conditions are warm enough. By the time it's safe to transplant, your marigolds will already have had a strong head start.
- When started indoors earlier, marigolds will bloom sooner after being transplanted, giving you a longer flowering season.
Planting Time For Marigolds
A general rule of thumb is to plant marigold seeds indoors 6-8 weeks before the last expected frost date.
Some factors influencing timing include:
- your local growing zone and frost date.
- and the marigold variety that you are planting (some may take longer to mature than others).
To find the last frost date for your location, use this handy frost date calculator from the Farmer's Almanac, and just add your postal or zip code for the dates.
Materials You Will Need:
To plant marigold seeds indoors, here is a list of materials you will need:
- marigold seeds
- a planting tray or container
- a good soilless mix
- a grow light
- heat mat (optional)
- a container for bottom watering
Step By Step Guide For Starting Your Seeds
- Fill your tray with the soilless mix. I use a 72 cell seed starting tray, which gives the seedlings lots of room to grow until they get planted out.
- Make a little indent in the centre of each cell about ¼ of an inch deep. You can do this pretty quickly with your finger.
- Drop a marigold seed into each cell, and into the hole you just created. Cover with more soil, or vermiculite, which is my favorite.
- Bottom water the tray until saturated. Make sure to check for moisture while the seeds are germinating, and water as needed to maintain a moist environment. Marigold seeds typically sprout in 4–14 days.
- Place on a heat mat until 60% of the seeds have germinated. Then place under a grow light until ready to be moved outside.
- Bottom water as necessary.
- It doesn't take long for the marigold seedlings to grow to a good size, especially if you have planted one of the giant varieties.
Transplanting The Seedlings Outdoors
Once your marigold seedlings have grown strong indoors, it's time to move them to their permanent spot in the garden. Proper transplanting ensures healthy plants that will thrive and bloom all season long.
When To Transplant
Plant out after your last frost date. Marigolds are warm season flowers and should only be transplanted when all risk of frost has passed.
Soil temperature should be consistently above 60°F (16°C) for optimal root growth. To ensure this, wait until nighttime temperatures stay above 50°F (10°C)
Make sure not to transplant however until the seedlings have been successfully hardened off!
Hardening Off the Seedlings
The seedlings will require hardening off before being transplanted into the garden.
This process gradually introduces the young plants to outdoor sunlight, wind and fluctuating temperatures. It's a very important step to prevent transplant shock.
To harden off your seedlings, follow a flexible schedule to toughen up the plants, over a period of one week or even longer.
- On day 1-3 place seedlings in a shaded and sheltered spot for a few hours, bringing them in at night.
- On day 4-6 gradually increase exposure, and reduce watering slightly to toughen them up.
- Be flexible with extreme weather conditions, and protect your seedlings from harsh temperatures, rain and wind. Alter your schedule if necessary!
- On days 7-10 leave the seedlings outside overnight, if conditions are favorable, and temperatures remain mild.
By the end of this process your seedlings will be much tougher, and ready to withstand full sun exposure, wind and rain.
Choose the Best Planting Location
Marigolds thrive in:
- Full Sun:(at least 6-8 hours of direct sunlight per day).
- Well Draining Soil: (loamy or sandy soil enriched with compost is ideal).
- Good Air Circulation: (space well to prevent fungal diseases). Smaller varieties can be planted 6-12 inches apart, while larger varieties need more room, and should be spaced 12-18 inches apart.
Aftercare: Helping Transplanted Marigolds Thrive
- Watering: Keep the soil evenly moist for the first week or two after transplanting, as the roots become established in their new location. After establishment, marigolds are drought tolerant, and require watering only when the soil is dry.
- Mulching (optional): A thin layer of mulch helps retain soil moisture and suppress weeds.
- Deadheading: Regularly remove faded flowers to encourage continuous blooming. This helps to prevent seed formation, which draws the plant's energy away from flower production.
- Fertilizing: Light feeding with a balanced fertilizer every 4-6 weeks promotes healthy growth but avoid excessive nitrogen.
In Summary
Marigolds are fabulous cut flowers, and I make sure to start them early in our zone 5 garden, so that I can cut from them throughout the entire summer!
Starting the seeds indoors sets your garden up for success, offering earlier beauty, and a longer growing season.
Transplanting the seedlings properly ensures a season full of bright, cheerful blooms.
With the right preparation, care, and attention to timing, your marigolds will flourish in garden beds, borders, or containers.
Have you ever started marigolds from seed indoors for early summer blooms? Be sure to leave a comment below to share your experience!
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