Sunflower Seed Growing Information

Some have been growing sunflowers for years. For others, this is your first try. We have assembled some basic information and tips for you to increase your chances of success.

Sunflowers are full-sun loving plants that love warm weather. Optimal germination is at soil temperatures of 70 degrees or more. Check below to see when that might before for your area.

Planting seeds outdoors: Plant the seeds an inch below the soil in a weed-free environment.  Keep the seed bed well watered until the sprouts appear.  If you have problems with animals wanting to eat them, set up some rabbit fencing and cover with chicken wire for 2-3 weeks until the plants are tall enough to survive on their own.  Alternatively, sprinkle some blood meal in the area where the seeds are planted to repel unwanted animals. Plant dwarf seeds 8-12" apart; 4-5 feet tall and 5-6 feet tall 12-18" apart; and taller varieties 18-24" apart. Keep the young plants well watered for the first three weeks or so.  Once they start developing strong roots and growing quickly, back off on the watering. If you have frequent rains, that's probably all the water they will need.  Think of where sunflowers grow really well, in somewhat drier areas like Kansas and Nebraska.

For those in cold-climate zones, you can try these tips to get a head start on 1/3 of your sunflower seeds.: You will need a heat mat and a grow light. About 5 weeks before the average date of last frost, , moisten several thicknesses of paper towels. Wring out excess water.  Open up and arrange the sunflower seeds in the center. Close up the sides, making a packet. Place the packet in a zip lock bag, label carefully and seal.  Place the zip lock bag on a heat mat.  Turn on the mat.  The seeds should start to germinate in 48-72hours.  2-3 days after germination, carefully place each sprout in a container filled with sterile growing medium.  I use a toothpick for this, gently taking each sprout and putting the roots downward and the leaves upward.  Water thoroughly and give the young sprouts as much light as you can. As the plants grow, keep the soil moist but not soaking wet.  You will notice that the plants will bend towards the light source.  Every other day or say, rotate the plants so they don’t become lopsided. Around the day of the last frost, carefully transplant the plants outside, giving the same spacing as you will for the seeds you will be starting outdoors.  Give them plenty of water as a weed-free of an environment as possible. I recommend planting the rest of the seeds in stages, another 1/3 mid-late May and then the rest 10-14 days later.  This will give you a longer total bloom time, with color well into September.

Here are some tips on getting a headstart on dwarf sunflowers grown in cold winter locations: Since your sunflowers will be growing in containers, here are some tips that you can employ to get a head start on those in your climate zone who will be growing their sunflowers in outdoor gardens.  Start your seeds indoors about 5 weeks before the average last date of frost in your area.  Fill some small but deep containers with a good sterile growing medium.  Gently press the medium down and refill.  In the center of the plug cell or other container, press down about one inch and place the sunflower seed in the divot.  Place more growing medium over the seed to the level of the surrounding soil.  Carefully label the cell or container with the name of the variety and date that the seed was planted.  Repeat the process for as many seeds as you want to plant and for additional varieties. 

You will have the greatest overall success when you have multiple plants growing in some containers, depending on the size of the container and the size that the plants will reach.  In an 8-10” diameter pot you could have a couple of plants, but in a large patio planter you might have four or more.  You could mix plants of different varieties in one large planter.  The number of combinations is literally endless!

Carefully water the plugs or containers with the planted seeds.  This is most effectively done with a spray bottle misting the soil in each container for few seconds multiple times.  You want the soil to be moist all the way to an inch below the level of the seed itself.  You will need to reapply the misting procedure at least daily until the seeds begin to sprout and emerge.  This could take anywhere for 3-4 days to 10-12 days depending on the variety.

Once, the seeds begin to emerge, give them as much sun exposure as you can, southern facing being the ideal.  Sunflowers are famous for being heliotropic, that is, they grow towards the light.  As your young sprouts are growing, rotate the cell or container each day so that the previous day’s growth is away from the light, forcing the plant to readjust.  This procedure will produce the strongest seedlings in the long run.

Your young sprouts will be developing longer roots so it is now time to change the watering procedure.  I recommend that you bottom water.  This is accomplished by placing an inch or so of water in a container or tray larger than the container that the sprouts are in.  Just place the container with the sunflower sprouts into the tray with the water and allow the water to percolate up through the growing medium.  Add more water if needed.  After 10-15 minutes, you can place the containers with sprouts back where they were.  The bottoms are going to be wet, so put down towels or some other protection to prevent unwanted water damage.  The entire soil depth in the container is now saturated.  You should be OK repeating this procedure every 3 to 4 days.  You will get the hang of it over time.

At some point your seedlings will start to grow more quickly.  I call this “bulking up”.  It is helpful to fill your spray bottle with a plant fertilizer that is absorbed by the leaves, spraying it on the sprouts every morning and evening.  Also, as they grow, you will notice a change in the color of the leaves from light to darker green.  This is a healthy sign.

You eventually will be itching to get the sprouts in the containers, their “forever homes”.  The timing of this procedure varies, and it is largely really up to you.  I would wait until the seedlings are at least 3 weeks old.  The most telling piece of information is the depth and vitality of the seedling’s root structure.  If it appears that the roots have maxed out the plug or container that they are growing in, then it is time to carefully transplant them.

I say carefully because many varieties of sunflowers resent being transplanted.  Their roots don’t like being touched or disturbed.  Yet, in this case, you can handle the plants extremely gently to the point that they will actually enjoy their new environment, the one in which they will grow and thrive, and for your benefit, bloom beautifully!

Fill the container or planter that the plants will be growing in with a good growing medium, perhaps adding in a slow-release fertilizer.  Tamp down and refill.  Dig holes where you want the sunflower plants to grow, giving them plenty of room to grow according to their mature heights.  Ultra-carefully, remove a sprout from its container, trying to disturb the roots as little as possible.  I do this with the long part of a metal spoon, gently just prying the growing plant out.  DO NOT grab hold of the leaves and pull the plant out.  You may even rip the root ball in the process.  Now simply plant the plug in the holes that you have previously dug.  Make sure at this point that you make a label for each plant stating the name of the variety.  (Wooden popsicle sticks and a fine permanent marker are helpful here).

Now it is watering time.  The long-term goal is to keep the entire body of soil moist, but not soaking, giving the roots access to all the moisture and nutrients that they want.  You will discover that there is a delicate balance between under- and overwatering.  And of course, many containers will receive plain old rain as their main source of moisture.

Here are approximate dates when the soil temperature reaches 70 degrees in several areas and cities of the country:

Year-round:  Hawaii

End of March:  Los Angeles

Early April:  Austin TX; San Diego

April 10th:  Dallas

Mid-April:  Atlanta; Raleigh NC

April 22nd:  Santa Barbara, CA

End of April:  Athens GA; Columbia SC; Charlotte NC; Sacramento CA

Beginning of May:  Baltimore; Kansas City; San Francisco; San Jose

May 10th:  Annapolis MD; New Haven CT; North Jersey

Mid-May:  Albany NY; Champaign-Urbana IL; Cleveland OH; Detroit; Eastern Connecticut; Eugene OR; New York City; Omaha NE; Philadelphia; Portland; Rhode Island; Seattle; Northern Virginia

Last half of May:  Delaware; Hartford; Pittsburgh; Rochester, Ithaca and Syracuse NY; Westchester County NY

May 23rd:  Connecticut; Lansing MI; Maryland; Worcester MA

Last 1/3 or May:  Columbus OH; Madison WI; Minneapolis

End of May:  Ann Arbor MI; Bend OR; Boston; Cape Cod; Chicago; Corvallis OR; Long Island; Milwaukee WI; Northwest Connecticut; Rockford IL; Santa Fe; Western Massachusetts

Beginning of June:  Boulder, Denver, Fort Collins CO

Varies:  Maine, New Hampshire, Vermont

Go HERE to figure out the date for your area: