Tubers are the roots of mature plants and look like a cluster of brown, carrot-like roots joined by the previous year’s dried stem. You can buy them from garden centres or by mail order in spring, or use your own tubers that you have overwintered.
Dahlias will come back every year, but if you live in an area with cold winters, it’s best to move them indoors in autumn. Those planted in pots can simply be moved to a frost-free spot, such as an unheated greenhouse. For dahlias growing in the ground, you will need to lift and store the tubers and store them in a pot of dry compost. Then, in spring, replant the loose tubers in the ground and refresh the compost of potted dahlias to give them a fresh burst of nutrients necessary for a good summer display.
Starting dahlia tubers indoors is a great way to get a head start on the growing season By planting tubers inside and getting them to sprout weeks before your last expected frost date, you can enjoy bigger, better blooms earlier in the summer.
As an avid gardener, I look forward to growing dahlias each year. Their brightly colored, diverse blooms add vibrant pops of color to flower beds and containers from midsummer until the first hard frost By starting the tubers indoors, I’m able to get a jump on the season for faster growth, earlier flowering, and higher yield
If you want to get your dahlias off to an early start this year here is a step-by-step guide to successfully starting them inside
When to Begin
Timing is important when starting dahlias indoors. You’ll want to begin the process 4-6 weeks before your expected last spring frost date. For most regions, aim to start dahlias in early to mid-April. Dahlias require warm soil temperatures to sprout and grow properly, around 65°F or warmer. If it’s too cold, tuber growth can be delayed.
Select the Right Container
Choosing an appropriately sized container is key. Select a pot at least 4 inches wide and deep, but larger pots up to 6-8 inches wide also work well. This gives the sprouting tubers enough room to develop a healthy root system before being transplanted outside. The container material can be plastic, terracotta, wood or any material with drainage holes. Darker colored pots absorb heat better than light colors if starting seeds indoors.
Use a Potting Mix
A loose, well-draining potting mix is ideal for starting dahlia tubers. Pre-moisten the soil before planting, then let excess water drain out so it’s moist but not soggy. Good potting mixes for dahlias include seed starting mix, potting soil, or a blend of compost and vermiculite or perlite for drainage. Avoid heavy garden soil which stays too wet.
Plant Tubers Correctly
Place 1 dahlia tuber horizontally in each container, about 2-3 inches deep. Position it so the top (crown) faces up. If the tuber has a distinct top vs. bottom orientation, plant it right-side up. Otherwise lay it on its side. Cover the tuber with potting mix so just the very top crown remains visible.
Provide Warmth and Light
Maintain temperatures around 70°F or warmer for fast sprouting. Place pots in a sunny window or under grow lights on a 14-16 hour daily schedule. Once sprouted, move plants outdoors daily to harden off as weather warms above 60°F. Avoid direct sun initially.
Water Carefully
Avoid overwatering which can cause rotting tubers. Wait to water until sprouts emerge, then moisten soil without saturating it. Let excess drain out. Allow the top inch of soil to dry between waterings for best results. Too much moisture is worse than under-watering.
Fertilize Lightly
Use half strength liquid fertilizer once sprouts appear and again when true leaves form. Applying too much fertilizer on young seedlings can cause leggy, weak growth. Go light on nutrients until plants are more established. Fish emulsion, compost tea, seaweed extract and all-purpose fertilizers work well.
Transplant Outdoors
Move dahlias outdoors when nighttime temperatures stay above 50°F consistently. Harden off plants first by slowly increasing their sun and wind exposure over 7-10 days. Plant them in garden beds or containers with rich, well-draining soil in full sun exposure. Bury the tuber crown just below the soil surface and space plants 12+ inches apart.
Troubleshooting Issues
- Leggy seedlings – Not enough sun, increase light exposure
- Leaf curl/cupping – Too much sun, move to partial shade and harden off gradually
- Failure to sprout – Soil too cold, maintain warmer temperatures
- Weak/dead sprouts – Tuber rot due to overwatering, plant new tubers
By following these simple tips for starting dahlias indoors, you can get your tubers off to an early start for maximum flowering this summer. Just be sure to harden them off and transplant outside after all danger of frost has passed. With proper care and timing, you’ll be rewarded with vigorous, flourishing dahlia plants and spectacular blooms.
Step 1[image id=”220781″ size=”landscape_thumbnail” title=”Planting dahlia tubers in a pot. Sarah Cuttle” alt=”Planting dahlia tubers in a pot. Sarah Cuttle” classes=””] Planting dahlia tubers in a pot. Sarah Cuttle
When planting dahlia tubers, ensure the joint where the roots meet the stem is facing upwards. Label your pots and grow on in a greenhouse or sunny windowsill. Keep the tubers well watered.
When to plant dahlia tubers
Starting dahlias in pots is a great way to get them into growth earlier in the season. Simply plant dahlia tubers in large pots filled with peat-free, multi-purpose potting compost in March or early April, and then keep them on a windowsill or in a frost-free greenhouse until late May, when it’s safe to plant them outside.
Starting off dahlia in pots will also encourage them to develop more quickly, so they’re likely to start flowering earlier. Before planting, soak the tubers in a bucket of tepid water for an hour so they can fully rehydrate.
Starting Dahlias Early Indoors | Let’s Grow Stuff
FAQ
What is the best way to start dahlia tubers indoors?
Put in a really warm spot in your home (next to a radiator or heater, a sunny window, or under grow lights where heat radiates from the lighting). This is a simple way to wake up your dahlia tubers before planting outside so they sprout sooner.
How do you wake up dahlia tubers in pots?
Starting off dahlia in pots will also encourage them to develop more quickly, so they’re likely to start flowering earlier. Before planting, soak the tubers in a bucket of tepid water for an hour so they can fully rehydrate.
How do you start dahlia seeds inside?
Sprinkle your dahlia seed over the top of the soil. Then lightly cover with potting soil. Lightly water so the soil is damp and continue to water lightly, keeping the soil damp during sprouting. Sprouting should occur within a 7–14 day period.
Do you need to soak dahlia tubers before planting?
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Not Mandatory, But Beneficial:Soaking dahlia tubers is an optional step, but it can be beneficial for rehydrating them, especially if they’ve been stored for a while or appear dry.
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Soaking Method:If you choose to soak, place the tubers in a bucket of lukewarm water for about an hour before planting.
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Purpose of Soaking:Soaking helps the tubers absorb water, which can encourage faster sprouting and growth.
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Planting After Soaking:After soaking, plant the tubers in pots or directly in the ground, ensuring the growing eye (the small, raised area) is facing upwards.
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Watering After Planting:After planting, water the soil lightly, but avoid overwatering, as this can lead to rot.
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Pre-sprouting:Some gardeners choose to pre-sprout dahlia tubers before planting, which involves storing them in a cool, humid environment until they start to sprout.
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Timing:Dahlia tubers are typically planted in spring, after the last frost, and can be started indoors 4-6 weeks before the last frost date.
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Spacing:When planting, ensure there’s enough space between plants, as dahlias can grow quite large.
Should I start dahlias indoors?
This guide unveils the secrets to successfully starting dahlias indoors for an earlier and more rewarding bloom season. Earlier Blooms: Get a head start and enjoy stunning dahlias weeks before those planted directly outside. Pre-sprouting indoors allows them to establish strong root systems before the warmth arrives.
When should you start dahlia tubers indoors?
Starting dahlia tubers indoors is an excellent option for those looking to get a head start on the growing season. But, when should you start dahlias indoors? The ideal time to start dahlias indoors is in early April, about six to eight weeks before the last frost date in your area.
How do I start dahlias inside?
Follow this simple process for successfully starting dahlias inside For most areas, aim to begin in early to mid April Dahlias need warm soil to sprout and grow properly. Select a pot at least 4 inches wide and deep or larger to allow adequate room for early root growth. Pot material can be plastic, terracotta, wood, or other.
Can you grow dahlias from seed?
Starting dahlias indoors from seed is easier than you might expect, and it’s one of my absolute favorite things to experiment with in the garden. Such an impressive flower comes from such an unimposing seed. The first time we grew dahlias was in 2021.
How do you plant a dahlia tuber?
To begin, fill a 4-inch-diameter pot or larger about one-half full with a potting mix. Place your dahlia tuber vertically in the potting mix so that you can see the neck, and cover the rest of the pot with potting soil. Be careful not to water the soil immediately, wait until you see eye development (see below) before watering.
How do you grow a dahlia indoors?
Try to master the temperature, humidity levels, watering needs, soil requirements, and all of the essentials to help a Dahlia thrive indoors. In this article, you’ll find everything you need to grow your dahlia to its full potential.