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Growing sunflowers in your landscape provides big yellow blooms that simply shout summer. Birds flock to the mature plants to enjoy the seeds, so you can use it as part of a plot planted to attract birds, bees, and other pollinators. Do sunflowers transplant well though and should you move them at all? Read on to learn more.
Starting sunflowers from seed indoors provides many benefits, including getting a head start on the growing season. However, timing is crucial when it comes to transplanting sunflower seedlings into the garden. Move them at the right growth stage and you’ll give them the best chance to thrive. Transplant too early or late and you risk stunting your sunflowers. This guide covers everything you need to know about identifying when your seedlings are ready to be moved outdoors.
Why Start Sunflowers Indoors?
While you can certainly direct sow sunflower seeds into the garden once the danger of frost has passed starting them indoors has advantages
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Allows growing sunflowers in cooler climates with a shorter outdoor season. The head start extends time to mature and flower.
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Protects vulnerable seedlings from late frosts heavy rains animals, and other hazards while starting seeds.
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Lets you pre-sprout seeds to test viability before putting in the ground.
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Provides ideal warm, humid conditions for germination and stocky growth.
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Gives control over transplant timing rather than waiting weeks for ideal outdoor sowing temperatures.
As long as you properly harden off and transplant at the right stage, indoor-started sunflowers will get a robust early start.
Signs Sunflower Seedlings Are Ready for Transplanting
Rushing to transplant seedlings too early is a very common mistake. Look for these cues that they are mature enough to move to the garden:
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Reached 4-6 inches in height – Sunflower taproots grow rapidly right from the start. Adequate top growth is needed before exposing roots.
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First true leaves emerge – Seed leaves (cotyledons) are small and round. True leaves are paired and look like mature foliage. Wait for 2+ sets.
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Roots fill container – Gently tip to inspect roots. They should hold together the soil when removed from the pot. Avoid circling roots.
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Hardened off for 7-10 days – Seedlings must gradually acclimate to outdoor conditions before going in the garden.
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No risk of frost – Transplant after all danger of frost is gone. Sunflowers grow best with minimum temps of 55-60°F.
The optimal size is around 4-6 inches tall. Mature enough to handle but still small and compact. Don’t exceed 10 inches or taproot growth will be stunted.
Transplanting Sunflower Seedlings in 6 Steps
Follow this straightforward process for moving seedlings into the garden with the least stress:
Step 1: Water Seedlings
Moisten soil a few hours before transplanting. Damp soil prevents root damage. Allow excess water to drain first.
Step 2: Dig Holes
Space holes 18-24 inches apart in the garden. Make them wider and deeper than the root ball.
Step 3: Gently Remove
Carefully take the seedling out of its pot, handling leaves rather than the stem. Disturb roots as little as possible.
Step 4: Place in Hole
Put in hole at same depth it was growing at in the container. Backfill soil around stem and firm gently.
Step 5: Water Transplants
Thoroughly soak to eliminate air pockets. Consider using transplant fertilizer to reduce shock.
Step 6: Provide Shade
Give afternoon shade for a few days until seedlings adjust to sunlight levels. Monitor soil moisture.
Follow proper spacing for your variety to avoid overcrowding. Dwarf sunflowers can go as close as 9 inches while giant types need 18-36 inches between plants.
Common Mistakes to Avoid
Some key pitfalls to avoid when moving sunflower seedlings:
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Transplanting before seedlings are sturdy and developed enough. Results in stunted growth.
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Letting seedlings become rootbound in containers. Binded roots struggle to establish.
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Damaging roots or packing soil too tightly during transplant.
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Allowing seedlings to wilt, dry out, or become stressed. Keep seedlings hydrated.
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Transplanting in hot midday sun or just before a heatwave. Pick cool mornings if possible.
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Forgetting to harden off seedlings before putting them in the ground. Gradual acclimation prevents shock.
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Not staking tall varieties. Sunflowers need support in windy areas.
Carefully monitor seedlings and transplant at the right stage when they have leaves, filled roots, are hardened off, and after all danger of frost has passed. Proper timing prevents stunting this iconic flower.
How to Harden Off Sunflower Seedlings
Hardening off is gradually acclimating seedlings to outdoor conditions over 7-10 days before transplanting into the garden. This toughens plants and prevents transplant shock. Follow these steps:
Phase 1:
Bring seedlings outside to a shady spot for 2-3 hours a day for 2-3 days. Take back indoors overnight.
Phase 2:
Increase outdoor time to 4-6 hours a day in partial sun for 2-3 days. Take indoors at night.
Phase 3:
Leave seedlings outside all day and night for 2-3 days in partial shade. Shelter if frost or rain expected.
Phase 4:
Move seedlings to full sun for 2-3 days, watching for stress signs. Water daily.
Phase 5:
On transplant day, garden soil will feel familiar. Proceed with moving into the ground.
Going slowly allows plants to build cuticles and adjust to outdoor wind, sunlight intensity, temperature shifts, and lower humidity before transplanting.
Caring for Seedlings After Transplanting
Sunflowers need a little extra attention after being moved to the garden:
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Provide afternoon shade for 2-3 days until plants adjust.
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Check soil moisture frequently and water whenever the top few inches become dry. Prioritize consistency.
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Consider using plastic mulch to warm soil, deter weeds, and conserve moisture.
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Fertilize lightly 2-3 weeks after transplant if growth is slow using a balanced liquid feed.
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Watch for slugs, snails, earwigs and other pests that attack seedlings. Remove by hand.
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Install support cages, stakes, or trellises before plants get large and unwieldy.
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Carefully weed around seedlings to prevent competition for water and nutrients.
With attentive care throughout the transplant process and beyond, your sunflowers will reward you with their big, bright yellow blooms all summer long.
When is it Too Late to Transplant Sunflowers?
Mature sunflowers with large root systems do not transplant well and risk dying from the move. Avoid transplanting sunflowers once they meet these thresholds:
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Over 2 months old – Large taproot is established. Moving risks breaking the taproot.
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More than 1 foot tall – Taproot is rapidly expanding making relocation difficult.
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Flower bud visible – Plant is putting energy into blooming rather than root recovery from transplant shock.
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Taproot over 8 inches – Large, deep taproot is anchoring the plant. Difficult to dig up intact.
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Lower leaves dying – Sign of plant maturity. Transplant shock is more likely.
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After June – The peak transplant window is April and May. Heat and maturity increase failure risk.
While it’s possible to transplant an older sunflower successfully, the odds are not favorable. For mature plants, it’s best to simply let them complete their life cycle where they are growing.
Transplanting Tips for Sunflower Success
Follow these tips to ensure your sunflower transplants get off to the healthiest start possible:
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Direct sow seeds whenever possible to avoid transplanting altogether.
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Use biodegradable pots to minimize root disturbances during transplanting.
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Transplant on an overcast, mild day to reduce stress on seedlings.
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Keep seedlings hydrated but avoid saturated soil that can cause root rot.
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Prepare a hole larger than the root ball with nutrient-rich soil for transplanting.
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Handle seedlings gently by their leaves instead of the fragile stem.
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Firm soil around roots and eliminate air pockets that can dry roots.
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Provide support for tall varieties after transplanting while stems are still flexible.
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Monitor for pests like slugs that attack vulnerable newly transplanted seedlings.
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Water frequently after transplanting until seedlings show new growth.
When you transplant at just the right time and follow best practices, your sunflowers will thrive in their new garden homes. Time those seedlings perfectly for summer flowers that reach their full towering height and beauty.
Tips for Moving Sunflower Plants
Since the seeds are large, grow quickly, and have a long taproot, moving sunflower plants from the sprouting container into the ground can be tricky. Do this less than three weeks after planting or as soon as you see leaves developing. If you leave plants in the starting container too long, growth of the long taproot may be stunted.
The best way to grow sunflowers is by planting seeds directly into the ground when soil has warmed and frost danger is passed. If for some reason you must start sunflowers in containers, use pots that are biodegradable and remove them as you’re putting the plant into a hole. Make sure dirt is loosened several inches (8 cm.) underneath to provide room for the taproot to grow.
If you buy a growing sunflower in a pot, look closely to make sure top growth appears healthy and, if you can, take a look at the roots. Don’t purchase this plant if it appears rootbound.
If you want to grow sunflowers in a container, choose a pot that is deep and possibly a dwarf variety of the plant. Sources say a one to two gallon pot is big enough for a dwarf plant and that the mammoth types need at least a five gallon container. Sunflowers growing in a container will likely need staking too.
Do Sunflowers Transplant Well?
Put sunflowers in their permanent location when planting. Due to their taproot, moving plants is not advisable. It is nearly impossible to move growing plants with taproots once active growth has started.
Can you transplant sunflowers from a starting pot? If you want to get started early growing this plant, you may grow from seed in a container. Transplanting sunflower seedlings shortly after sprouting is the best practice.
Transplanting Sunflower Seedlings
FAQ
How tall should sunflower seedlings be before transplanting?
Keep sunflower seedlings warm and well watered, and repot into the next size larger pot each month. They’re ready to go out once they’re 30cm (1ft) tall and the weather outside is warm, usually early June. Sunflowers sown outside often grow into sturdier plants, but they’re more vulnerable to pests.
Do sunflowers transplant well?
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Taproot Sensitivity:Sunflowers develop a strong, deep taproot, which can be damaged during transplanting, potentially leading to poor growth or even death.
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Best Practice: Direct Sowing:The most reliable method for growing sunflowers is to sow seeds directly into the ground when the soil has warmed and the threat of frost has passed.
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Transplanting Considerations:
- Timing: If you must transplant, do it shortly after the seedlings sprout, before the taproot becomes too long and established.
- Container Choice: If starting sunflowers in containers, use biodegradable pots to minimize root disturbance during transplanting.
- Careful Handling: When transplanting, handle the seedlings gently, avoiding damage to the roots.
- Soil Preparation: Ensure the soil is well-draining and loosened several inches deep to allow the taproot to grow freely.
- Timing: If you must transplant, do it shortly after the seedlings sprout, before the taproot becomes too long and established.
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Reasons for Transplanting:
- Pest Control: Starting seeds indoors can help prevent them from being eaten by birds, squirrels, or chipmunks.
- Head Start: Transplanting can give sunflowers a head start, especially in regions with shorter growing seasons.
- Privacy Fencing: Sunflowers can be used as a quick-growing privacy screen, and transplanting can help ensure a full, dense planting.
- Pest Control: Starting seeds indoors can help prevent them from being eaten by birds, squirrels, or chipmunks.
When can I plant sunflower seedlings outside?
- Timing:
- Southern California (Los Angeles): The best time to plant sunflower seedlings outside is after the last expected frost, which usually falls around late April or early May.
- Direct Sowing: You can also sow sunflower seeds directly into the ground after the soil has warmed up, which is also around late April or early May.
- Southern California (Los Angeles): The best time to plant sunflower seedlings outside is after the last expected frost, which usually falls around late April or early May.
- Soil Temperature: Ensure the soil temperature is at least 50°F (10°C) before planting.
- Seedling Size: Transplant sunflower seedlings when they are about 4-6 inches tall and have developed a strong root system.
- Location: Choose a location that receives full sun and has well-draining soil.
- Spacing: Space seedlings about 18-24 inches apart to allow for proper air circulation and room for growth.
- Hardening Off: Before transplanting, gradually acclimate the seedlings to outdoor conditions by setting them outside for a few hours each day, gradually increasing the time, and bringing them in at night.
- Watering: Water the seedlings well after transplanting and continue to provide consistent moisture until the plants are established.
Do sunflowers like to be repotted?
But when they get bigger, sunflowers also benefit from up-potting. This means that you need to be clued up on when to repot sunflower seedlings to ensure that the growing plants are getting all of the extra nutrients they need to thrive in these larger pots.
Can You transplant sunflowers?
Yes, you can transplant sunflowers. Sunflowers have a deep taproot, so it’s best to transplant them when they are still young and have smaller roots. Make sure to choose a sunny spot with well-draining soil and water them regularly until they establish in their new location. Discover the step-by-step guide on how to transplant sunflowers.
When to transplant sunflower seedlings?
The first step in deciding when to transplant sunflower seedlings is to understand the optimal soil temperature for transplanting. Sunflower seedlings should be transplanted when the soil temperature is between 55 and 65 degrees Fahrenheit. This ensures that the seedlings will have the best chance of surviving in their new environment.
How do you transplant a sunflower seed?
Water the seedlings thoroughly and place them in a sunny spot where they can continue to grow. If you’re transplanting sunflower seedlings directly into the ground, make sure the soil has warmed up and there’s no risk of frost. Sunflowers prefer well-draining soil that’s been enriched with compost or other organic matter.