The new year has been rung in, and it’s already time to think about starting seeds indoors for your spring vegetable garden. Marigold plants are a must-grow in your garden: they’re super low-maintenance, they add cheerful color to your garden, they thrive in many different soil types, and they even deter certain garden pests while attracting beneficial insects.

You’ll get blooms just 8 weeks after you sow your marigold seeds, and then you’ll continue to enjoy flowers all the way until your first light fall frost. It’s always sad to see your marigolds go, but don’t worry. If you left some spent flower heads on the plants, you’re likely going to get more marigolds the following spring—without having to lift a finger!

It’s so easy to plant and grow marigolds (and re-grow them next year, even if you’re not intending to) that the real question is: Should you start your marigolds inside? Let’s get into it!

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CAN YOU START MARIGOLD FLOWERS BY SEED INDOORS?

In theory, starting marigold seeds indoors means you’ll get a head start on the growing season and get your first fiery orange, golden yellow, or farmhouse red blooms sooner. That being said, marigolds germinate and grow very quickly from seed under the right conditions.

You can sprinkle some marigold seeds outdoors as soon as your last frost date has passed and have blooms in a matter of weeks. These flowers are really own worth your seed starting efforts if your live in a lower gardening zone and have very short summers. For those of us in higher hardiness zones, it’s best to direct sow marigolds seeds in the garden once all chance of frost has passed.

For those of you itching to bust out the ol’ seed starting trays, here’s your step-by-step guide to starting marigold flowers indoors.

when to start marigold seedlings

STEP ONE: DETERMINE THE BEST TIME TO START MARIGOLD FLOWER SEEDS

Don’t know when to sow? We’ve got you covered. Google the final frost date for your area, and then count back about 4-6 weeks. That’s when you’ll start marigold seeds indoors for best results. For those of us in Central Texas, we would start our seeds in early February so that we can transplant our marigold seedlings once our last anticipated frost date passes in mid-March.

Pro tip:

In case you’re still trying to decide which varieties of marigolds to grow, I love Favorite Blend French marigold, Lemon Gem, and Crackerjack African marigold seeds from Botanical Interests. If you come across seed packets for pot marigolds, just know that those are actually calendula plants (also totally worth growing in your garden for their pest control potential and beauty). Here’s our guide to growing calendula.

STEP TWO: GATHER YOUR SEED STARTING SUPPLIES

You’ll need the following seed starting supplies:

A Container to Start Your Seeds in

You can use plastic seed starting trays, biodegradable pots, soil blocks, empty toilet paper rolls—whatever you prefer.

Grow Lights

Using a grow light prevents your marigolds from growing leggy (too tall and slender). These wand lights are easy to maneuver up and down as your seedlings grow. Other options include artificial grow lights that can be affixed to a shelf (like lights mounted under a book case).

Organic Seed Starting Mix

Shop my recommended organic seed starting mixes here, or make your own by mixing equal parts coco coir, vermiculite, and perlite, plus some worm castings. I do recommend something organic since your marigolds will be visited frequently by pollinators like bees, butterflies, and hummingbirds.

A Heat Mat

A heat mat is really only necessary if your house is on the chillier side in late winter/early spring. Marigolds germinate best when the soil temperature is between 70°F and 75°F.

Extra: You might also want to have some plant tags to label your rows if you’re starting more than one variety of marigolds.

 

STEP THREE: FILL YOUR TRAY WITH PRE-MOISTENED SOIL

In a large bowl, rehydrate your seed starting mix by adding water and folding it in with your hands until it’s moist but not soggy. Fill your seed starting trays with the moistened soil mix. Press the mix down a little bit inside each cell and smooth out the surface.

STEP FOUR: SOW MARIGOLD SEEDS

Marigold seeds look like tiny batons with feathered ends. They don’t really need to be buried, so you can just place one little seed per cell, right on the soil surface. Place the batons flat on their side instead of trying to guess which way’s up or down. Don’t forget to label if you’re planting more than one type.

Once all your seeds are placed, sprinkle some more seed starting mix over them. Just a light layer—these seeds like to feel some light on them as they germinate.

STEP FIVE: KEEP SOIL MIX WARM & MOIST

Place your seed tray in a warm spot. If you have a heat mat, set your tray on top until you see the first little sprouts appear. (You don’t want to use the heat mat after that, or you can end up with leggy seedlings.) If you don’t have a mat, it’s no big deal. Set your tray on top of the fridge or dryer or even just a heating pad made for humans with the fabric cover removed. Warm soil tells seeds for warm-season annuals like marigolds that it’s time to grow.

Keep the soil moist until the seeds sprout by spritzing the top of the soil with water from a spray bottle and/or adding water to the bottom of the tray. Lock in moisture by covering your tray with a plastic dome if you have one. Otherwise, just use a kitchen towel or a piece of burlap. Again, remove this cover as soon as you see little green shoots appear. Marigolds usually take about 5 to 14 days to germinate.

STEP SIX: TURN ON GROW LIGHTS

Put your tray under lights as soon as your seeds have sprouted. (Don’t forget to also remove the heat mat and any covering.) Keep the lights about 2 inches above the marigold seedlings. If you happen to have a warm outdoor greenhouse, your marigold seedlings could hang out in there instead of under artificial lights.

STEP SEVEN: TEND YOUR GROWING MARIGOLD SEEDLINGS

Once your marigold seedlings have grown their first set of true leaves, use something like diluted seaweed extract to give them nutrition every 2 weeks. Aim a small fan turned on the lowest setting at your seedlings or run your hands back and forth over them a couple times a day to simulate wind. This prepares them for the great outdoors and encourages them to form strong roots.

STEP EIGHT: HARDEN YOUR MARIGOLD SEEDLINGS OFF

Before you move your marigolds to their new home in your garden, you have to get them used to outdoor conditions through a process called “hardening off” your seedlings. All this means is you should bring them outside for a few hours each day to adapt them to outside temperatures, sunlight, and wind, to reduce transplant shock.

Wait until all threat of frost has passed before you begin the hardening off process. Pick a week with nice, warm weather expected for the days. Start by placing your young plants in partial shade for the first couple of days; gradually move them to full sun as you increase their time spent oudoors. Begin with just an hour outside on day 1 and work up to full outdoor time over the course of a week.

STEP NINE: PLANT YOUR MARIGOLDS IN THE GARDEN

The time has finally come to transplant your marigolds. Smaller marigolds are great for planting in containers that have good drainage or along the borders of your garden.

Taller varieties are perfect for pollinator gardens (it doesn’t matter if you have poor soil) or the back of your raised beds, where they won’t block sunlight from your veggies. Pick a spot that receives full sun to maximize new blooms.

Add a layer of compost to the planting area. Dig planting holes that are as deep as your seed cells and twice as wide. Slide each little marigold from the tray carefully to minimize disturbances to the roots.

Check the spacing recommendations on the back of your seed packet for the species of marigolds you’re growing. French marigolds stay on the smaller side and can typically be planted closer together than larger varieties like African marigolds, which need like 18″ of space to themselves.

Water your marigolds in well.

Pro tip:

Plant marigolds near your leafy greens and any other plants that are prone to aphids. Marigolds attract beneficial insects like lacewings, ladybugs, and parasitic wasps (which sound bad but are actually good for your garden, I promise).

MARIGOLD PLANT CARE TIPS

Marigolds really are super low maintenance. Even so, here are some tips to ensure you have lots of beautiful flowers in a couple of weeks:

  1. Aim water at the base of the plant. Wet conditions on the leaves can cause issues like powdery mildew. You’ll find that you really don’t need to water marigolds very often at all.
  2. Marigolds repel many types of pests, everything from root-knot nematodes in the soil to rabbits and deer. Should you have any pest or fungus issues, treat them with Arber Bio Fungicide or Neem oil.
  3. Marigolds shouldn’t really need to be fertilized beyond the organic matter (compost) added at the time of planting. If you want to add more nutrients, I would use a slow-release liquid fertilizer like MicroLife Maximum Blooms.
  4. Pinch off spent flowers to encourage your plants to grow bushier and keep producing more blooms.

Marigolds are annual flowers, so you’ll have to start again next year. You can save spent flower heads from your garden and create your own endless seed supply for next year. You’ll also likely have some volunteer marigolds popping up in the spring. Free flowers!

That’s all there is to starting your marigolds indoors to get a jump start on your growing season. Shop our Amazon Store to find recommended items you can use for all your seed starting endeavors. Let us know if you have any questions!