How to Grow Tall Sunflowers in Raised Garden Beds

There are not many plants in the garden as fun to watch grow as a sunflower. It starts sprouting out of your soil a little more every day. One week it's a seedling, and a couple of months later you're looking up at it. 

Garden Tip: Though they have a reputation for being giants dwarf sunflowers give you the same big, sunny faces in a more compact version that fits right into a raised bed on your patio, deck or backyard. They're quick to bloom, easy to care for, and the bees love them just as much as the tall ones.

They're also a perfect match for a 12-inch-deep raised bed. Giant varieties need two feet or more of soil for their roots, but dwarf types are bred to stay compact, so they can put out there best blooms in compact spaces.

Here are our best tips for growing full, healthy dwarf sunflowers in raised garden beds.

Why Dwarf Sunflowers Are Perfect for Raised Beds

Every sunflower grows a taproot that heads straight down looking for water. On a 10-foot giant, that root can reach 2 to 3 feet deep. On a dwarf variety, the whole plant is scaled down, roots included. That's why dwarf sunflowers do so well in just 12-inches of soil: they have just the right amount of room without being cramped.

There are other benefits to dwarf varieties: Shorter plants stand up to wind without staking, they fit nicely alongside other flowers and veggies, and they're easy to see, water and enjoy up close. Plenty of dwarf varieties also branch out, giving you several blooms per plant instead of one.

Pick the Right Varieties

The most important step happens before you plant. Check the seed packet for the mature height, and look for varieties that stay around 1 to 4 feet tall. Here are a few of the favorites:

• Teddy Bear: fluffy, golden pom-pom blooms on plants around 2 to 3 feet tall.
• Big Smile: a classic yellow sunflower that stays a tidy 1 to 2 feet tall.
• Sunspot: short plants, usually around 2 feet, with surprisingly big flower heads.
• Music Box: a mix of yellow, red and cream blooms on branching plants around 2 to 3 feet tall.
• Elf: one of the smallest, often just over a foot tall.

Skip anything labeled "Mammoth," "Giant" or "Skyscraper." Those need a much deeper bed to stay healthy and upright.

Whatever you choose, wait until the soil has warmed to about 50°F and frost has passed before sowing. Seeds planted in cold soil tend to rot or stall, and the good news is that raised beds warm up faster than the ground.

Tip #1: Make the Most of Your Bed's Depth

A 12-inch deep bed is plenty for dwarf sunflowers, as long as you use every inch of it well. Fill it all the way to the top so roots have the full depth to work with, and top it up if the soil settles.

Drainage matters just as much as depth. Sunflowers like steady moisture, but soggy soil will rot their roots. Cedar is naturally rot-resistant and breathes a little, letting extra water escape while still holding some moisture on hot days. Our raised garden bed is a great size for a small cluster of dwarf sunflowers, and its raised height means the soil warms quickly in spring and drains well.

Set your bed in its final spot before filling it. Even a 12-inch bed full of damp soil is heavy to move.

Tip #2: Build Rich Soil and Feed Them Well

Sunflowers are hungry plants, even the small ones, and a raised bed lets you build great soil from scratch. Skip plain garden soil, which packs down and squeezes roots. Instead, try a mix of roughly 40% topsoil, 30% compost and 30% perlite, vermiculite or coarse sand. Sunflowers are happiest at a pH between 6.0 and 7.5, and each year it's worth mixing a couple of inches of fresh compost into the top of the bed.

For fertilizer, keep it simple:

• At planting: a balanced feed, like 10-10-10.
• While they're growing: a light balanced feed every couple of weeks.
• Once buds appear: switch to a feed slightly higher in phosphorus, like 10-20-10, to support the blooms.

Go easy on the nitrogen. Too much can give you lots of leaves and fewer flowers. Also keep in mind that nutrients wash out of raised beds faster than in-ground gardens, which is why regular light feeding works better than one big dose.

Tip #3: Water Deeply and Consistently

A 12-inch bed holds less water than a deep one, so it can dry out faster on hot days. That makes consistent watering one of the biggest keys to success.

Aim for about an inch of water a week, more during heat waves. Water deeply rather than giving a quick sprinkle, soaking the bed until water drains out the bottom. Not sure if it's time? Stick your finger a couple of inches into the soil. If it's dry, water. If it's still damp, check again tomorrow. In the peak of summer, that might mean checking every day.

Morning is the best time to water, since the leaves have all day to dry off. A 2-inch layer of straw or shredded bark around your plants will also help hold moisture in and keep the soil from baking.

Tip #4: Give Them All the Sun You Can

They're called sunflowers for a reason. Even dwarf varieties need at least 6 to 8 hours of direct sun a day. In shade, they get leggy, flop over and produce smaller blooms.

Spend a day noticing where the sun hits your yard or patio, and put your bed in the brightest spot you can find. South-facing areas usually get the most light. Raised beds also lift plants above low fences and railings, which can add an extra hour or two of sun.

The nice thing about dwarf sunflowers is that wind is rarely a problem. Most won't need staking at all. If you're growing one of the taller dwarf types, around 3 to 4 feet, in a very windy spot, a small bamboo stake is an easy fix.

Tip #5: Give Them Room to Bloom

It's tempting to pack a bed full of seeds, but crowded sunflowers compete for light, water and food, and you'll end up with smaller, weaker plants. Dwarf varieties can be planted closer than giants, but they still need some breathing room:

• Single-stem dwarfs (like Big Smile or Elf): about 6 inches apart
• Branching dwarfs (like Teddy Bear or Music Box): about 12 inches apart

To figure out how many fit, divide your bed's length in inches by your spacing and round down. For example, our raised garden beds fits 6 branching sunflowers at 12 inches apart, which makes a cheerful row along a fence or patio.

Sow 2 or 3 seeds per spot. Once the seedlings are 3 or 4 inches tall, keep the strongest one and snip the others at the soil with scissors. Snipping instead of pulling protects the roots of the one you're keeping.

Sunflower FAQ:

We've all made a few of these:

• Choosing a giant variety. Tall sunflowers need much deeper soil. Stick with dwarf types for a 12-inch bed.
• Planting in cold soil. Wait until it warms up and frost has passed.
• Letting the bed dry out. Shallower beds dry faster, so check the soil often.
• Too much nitrogen. It gives you lots of leaves and fewer flowers.
• Crowding. Give each plant space and thin out the extras.

Bonus: Keep the Blooms Coming

Want flowers for longer? Sow a few seeds every couple of weeks, and you'll have fresh blooms coming in one after another. On branching varieties, snipping off faded flowers also encourages the plant to produce more. And if you'd like to share with the birds, leave a few heads on at the end of the season for the finches and chickadees.

Big Blooms, Small Space

Dwarf sunflowers prove you don't need a huge yard or a giant plant to enjoy that classic sunflower cheer. Pick the right variety, give it rich soil, steady water, full sun and a little room, and your raised bed will be full of bright, happy blooms all season.

Raised garden beds are the perfect home for dwarf sunflowers and so much more. Made from naturally rot-resistant cedar, they'll be ready for your sunflowers, and whatever else you want to grow, for many seasons to come.