Growing and Caring for Sunflowers (A Complete Guide)

There are around 70 different types of sunflowers, ranging from the tiny ‘Elf’ variety at only 16 inches tall to the massive 12 to 15 foot ‘Titan’ variety and everywhere in between. Sunflowers also aren’t just brown and yellow anymore – different varieties come in ranges of yellows, reds, browns, oranges, coppers, and burgundy.

The flower types have also been expanded; the iconic image of petals surrounding the large circular interior are still the most common, but there are also varieties with small centers and layers of petals, double petal varieties, and some with so many tiny petals that they look more like a fuzzy puffball than a typical sunflower.

A number of varieties, including ‘Teddy Bear’, ‘Sunny Smile’ ‘Firecracker’, ‘Big Smile’ ‘Little Becka’, ‘Pacino’, ‘Lemon Queen’, ‘Suntastic Yellow’, ‘Suntastic Pink Bicolor’, and many more remain smaller in size and so can be easily grown indoors in containers, allowing you all the enjoyment of this distinctive flower without needing to sacrifice yard or house space. Of the dwarf varieties, the ‘Elf’, ‘Pacino’, and ‘Teddy Bear’ varieties have the best ratio of foliage to flower.

‘Teddy Bear’ sunflowers grow to be 2 or 3 feet tall, with multiple 4 to 6 inch orange puffball blooms. ‘Pacino’ sunflowers grow 12 to 16 inches with 5 inch yellow flowers with dark centers. ‘Elf’ sunflowers grow to be 16 inches tall with 4 inch golden flowers with dark centers. The larger varieties of sunflower can also be container grown if proper steps are taken to keep them healthy and happy.

Potting a Sunflower

If you decide to pot large sunflowers for indoor or outdoor growth, they need at least 5 gallon pots to have enough room for their roots to grow enough to support them. Dwarf varieties grow well in more manageable 12 inch to 16 inch pots.

Small peat pots are fine to use when sprouting and growing seedlings, though terracotta or clay pots are better to use for your plants than plastic pots are and should be used as the final pot for your plants if possible. Plastic pots keep water in the soil more than terracotta or clay will, which is not a good thing for your plant. This can lead to overwatering of the plant, which can damage the roots of the plant and lead to root rot.

Terracotta or clay pots will absorb some of the moisture in the dirt, keeping the plant healthier. Terracotta pots are significantly heavier than plastic pots, and if you mean to plant either a large variety of sunflower or multiple dwarf varieties in a single large pot the weight of the pot plus the soil can be significant. Make sure that your pot is either on wheels or placed where you want it to remain before planting for ease of care.

Another factor to keep in mind is if the weight of the filled pot will be supported by the structure it is placed on. While this won’t be an issue for pots placed on the ground, do make sure that if you place the pot on a balcony or deck it will be able to support the weight without becoming damaged.

The Best Soil for Sunflowers

Sunflowers grow well in general potting soil; some vermiculite can be added to the soil in larger pots to help keep the weight more manageable. Good quality organic compost can be mixed in either size pot as well. Check to be sure that your selected potting soil has an organic content of more than 3%, and that the soil pH is between 5.5 and 7.5, as sunflowers prefer their soil to be slightly acidic to slightly alkaline, with no extreme in either direction. 

The bag your soil comes in should have information on the organic content and the soil pH listed for easy reference.

Sunflower Care

Many sunflowers, including dwarf varieties, are annuals; this means they will grow, bloom, seed, and then die. New sunflowers will need to be planted every year if you want to continue to enjoy the flowers, but the process of doing so isn’t difficult. Sunflower seeds must be harvested from living plants, bought from a nursery or ordered from a catalogue; the sunflower seeds sold in grocery stores for snacking are heat treated and thus unable to germinate.

Sunflowers are typically planted in late spring, though if the plant is remaining indoors they can be planted at any time of year. Once the pot for your plant is filled with your selected soil, place the seeds an inch down into the soil.

If you’re putting multiple plants in one pot, make sure to leave 4 inches between the seeds to permit enough space for each sunflower to grow. Try to keep the seeds away from the edges of the pot when planting. Small peat pots can also be used to start sunflowers, though sunflowers do not handle transplanting very well and they would always prefer to be started in the pot you intend for them to grow in.

Within 2 to 10 days the seeds should have sprouted and grown into seedlings. Let the seedlings grow until they’ve put out 2 to 4 leaves, which will take them 2 or 3 weeks; at that point any plants you have sprouted outside of their pot can be transplanted from the peat starter pot to their permanent home.

If the seedlings are moving outside, it is important to let them acclimate to natural light slowly over the course of a week or two by exposing the plants to increasing amounts of light each day; this will keep them from getting burned. The seedlings should be full grown and flowering in about 3 months’ time.

Sunflowers need a lot of sun – 6 to 8 hours of direct sunlight is best for them, as the more light they receive, the better they will grow and flower. If you can’t place them in a south or west window to allow that, put your plant in an eastern window under an adjustable grow light.

Two cool white fluorescent tubes and two full spectrum fluorescent tubes will provide your plant with the light it needs. Keep the lights six inches above your sunflowers, raising them as necessary as the plant grows. The fixture should be plugged into a timer; set the lights to come on at sunup and remain on for 10 to 13 hours. Use of a grow light also means that your sunflowers will not be bound to the typical growing season – you can enjoy the sunny blooms even in the dead of winter.

Sunflowers grow best with a daytime temperature of around 72 degrees Fahrenheit, and a nighttime temperature of around 65 degrees Fahrenheit. 

While most dwarf sunflowers should not need to be staked, it is a good idea to stake any sunflowers growing over 3 feet tall. Anchor the stake to the wall or another object to prevent your plant’s pot from toppling over as it continues to grow and becomes top heavy. In addition to keeping your plants upright, staking your sunflower will help prevent the flowers from drooping.

Sunflower stems and leaves have a somewhat prickly surface. Wearing long sleeves and gloves, particularly when dealing with larger varieties of sunflower, will help keep your skin from becoming irritated when you handle them.

Watering and Fertilizing Sunflowers

Sunflowers are extremely thirsty plants and need to be watered very regularly. Add water to your plant’s pot when the first inch of soil feels dry; this may mean you have to water daily, or more than once daily, especially in hot weather conditions.

Water the sunflower thoroughly, allowing water to run out the drainage holes before stopping. Soil should be moist, but not wet. Any water left in the drip tray should be discarded when the plant soil has drained after watering. Sunflowers take in a lot of water while growing; if not watered enough, their stems will be thin and weak. If watered too much however, their leaves will turn yellow and droop.

Sunflowers should be fed a quality, water-soluble fertilizer high in nitrogen once a month while growing; this will help their foliage look its best. Switching to a liquid fertilizer high in phosphorus when the plant starts to form flowers will give bigger, brighter, longer-lasting blooms. Dilute the fertilizer as instructed by the packaging, and apply it to the plant immediately after watering.

Sunflower Pests, Diseases, and Other Issues

Sunflowers are a very hardy plant that have few major pests and diseases, and sunflowers grown indoors have even less. Still, it is a good idea to know what to keep an eye out for in case your plants summer outside or they do end up developing a disease.

– Sunflower Beetles are 1/4 to 1/2 inch insects that are cream colored with brown stripes. These insects eat the leaves of the plant, leaving a lacy look to the leaves they consume. Older plants are seldom badly damaged by the beetles, but seedlings and young plants can be severely damaged as the beetles eat their smaller and less numerous leaves. Beetles and larvae can be removed from the plant by hand, or an insecticide can be used on the plant.

– Cutworms feed on the stems and leaves of sunflowers, ‘cutting’ the stem entirely through or leaving visible notches where they don’t eat through. They can be difficult to spot in action due to being nighttime feeders. Cutworms can be removed either by picking them off the plant or surrounding your plant with a ring of diatomaceous earth. You can also wash your plants with non-bleach dish soap and water. Mix 1 1/2 teaspoons of dish soap into 1 quart of water; place into a spray bottle and spray the plant twice weekly until the cutworms are gone.

– Sunflower Moth larvae feed on the seeds of sunflowers. The larvae are 1/2 to 3/4 inch long and bore holes into the seeds of the plant; a single larvae will eat about 9 seeds over a 3 week period. The presence of silken webbing on mature seeds are an indication of the presence of Sunflower Moth larvae.

Insecticides containing containing carbamate, endosulfan or methidathion can be used to treat the plant, but will only kill young larvae and multiple treatments may be required to kill any subsequent larvae hatchings. The insecticide should be applied in the early morning or late afternoon when the sunflower begins to shed pollen. Waiting too long will allow the larvae to get into the seeds, protecting them from the treatment.

– Plant Rust is a group of fungi, each of which attack specific species of plants; this means that it will not jump from the infected plant to another type of plant, though it can move to other plants of the same species. This fungus is easily identified by rust-colored areas on plant stems and leaves, starting out as flecks and eventually growing into a series of distinctive bumps.

Rust fungus is most often found on the undersides of leaves. Rust fungus loves a wet environment, so be sure that your plants have good circulation and are not overwatered. Remove affected leaves as soon as you notice the presence of the fungus. 

– Verticillium Wilt is a fungal disease caused by the presence of the fungus in soil. Sunflowers planted in potting soil will very likely not develop this disease. It can be identified by the leaves of the plant (often on only one side) turning yellow or red, and wilting and curling; eventually the leaves will turn brown and fall off the plant. Once infected, the plants cannot be saved and must be removed.

The soil the plant was growing in will still have the fungus present, and so must be treated before it can be used to plant in again. Solarization, exposing the soil to sunlight over time, is an effective method of destroying the lingering Verticillium fungus.

– Powdery Mildew is a fungus that gives plants a speckled, fuzzy, powdery look. It is a common garden problem caused by wet conditions and poor circulation. In addition to removing the conditions that encourage the fungus growth, there are many commercially available fungicides that can be used to treat powdery mildew. Neem oil can also be used on affected plants.

– White Mold, also known as Sclerotinia Wilt, is a fungal infection that attacks the roots of the plant and causes stem and leaf wilt,  lesions on the stem, and eventual rot of the flowers. Overapplication of nitrogen-rich fertilizer can encourage the growth of white mold if the fungus is already present. Water sunflowers in the early morning; this will let the soil dry throughout the day make it less welcoming to the fungus. Remove infected plants and the soil surrounding them.

– Root Rot occurs when the plant remains in overwatered, poorly draining soil. Because the roots are destroyed, the plant withers and dies off. Plants with root rot should be removed.

Harvesting Sunflowers

Sunflowers, particularly the dwarf varieties, work well as cut flowers. Cut the flowers at an angle in the morning a few hours after watering, when the flowers are at their freshest, and immediately place them into water. The stems can be further cut as needed to fit your container of choice; do so under running water. The water in the flower’s vase should be changed every few days, as fresher water will help the bloom last longer. Making further cuts to the stem, removing small pieces each time, will also help prolong the life of the cut flower.

The seeds of your sunflowers can be harvested about 30 days after pollination. If you want to harvest your sunflower’s seeds, look for flower heads that have started to droop and are facing the ground with petals that have begun to wither, dry, and fall out.

If you prefer, you can cut the flower early and hang it in a secure location to dry; otherwise allow the flower head to dry completely before removing it from the plant stalk. Waiting until the back of the flower head has turned brown is a good way to know that your flower is dry enough for easy seed removal.

When the flower is dried, cut the head off the plant off the stalk, about six inches below the flower head if you haven’t removed it already, and place the cut flower head into a bowl to catch loose seeds as they drop out. Lay the flower flat on its back and pull the seeds out with your hand or by running a fork over the surface of the seeds to loosen them.

If you want to harvest seeds from an outside plant, place a paper bag over the flower while it dries to prevent birds from getting to the seeds before you can. Rinse the harvested seeds well, then lay them out on a flat surface to dry for several hours or overnight. If you plan to use the dried seeds for planting, store them in an airtight container in a cool, dark place until you’re ready to plant them.

If you don’t wish to save the seeds for planting, the small, dark variety of sunflower seeds can be fed to birds, either by harvesting them from the plant as directed above and placing them out to be eaten, or simply hanging the dried flower head for the birds to pick the seeds out of themselves.

The larger, striped variety of sunflower seeds can also be fed to birds, or they can be eaten with a little bit of preparation. Use them in bread or other recipes as called for, or roast them for snacking. Resoak the dried seeds in salted water overnight, then strain; lay on paper towels to dry.

Spread the seeds in a single layer on a baking sheet and bake them at 325 degrees Fahrenheit for 25 to 30 minutes, until lightly browned. Season as desired and store in an airtight container.

Raw sunflower seeds will last up to a year; roasted sunflower seeds will last 3 months. They can be kept longer by placing the roasted seeds in the fridge (6 months) or freezer (1 year).


I enjoy all things outdoors and I love plants! I've never considered myself to be one with a green thumb, but it's my mission to learn, so I figured I would bring you along for the ride. :) Happy planting!

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