Growing Dahlias in Grow Bags: A Complete Guide for Beginners

Dahlias are absolutely gorgeous flowers that can add a pop of color and vibrancy to any garden. While typically grown in beds, dahlias can also thrive when planted in grow bags Grow bags offer flexibility and convenience, making them a great option for beginners or anyone with limited space In this complete guide, we’ll cover everything you need to know about successfully growing dahlias in grow bags.

What are Grow Bags?

For those new to gardening, grow bags are fabric pots that can be filled with soil and used to grow plants. They come in a variety of sizes, shapes, and colors. The fabric is porous, allowing for air flow to the roots while also providing excellent drainage.

Grow bags make gardening extremely versatile. You can place them on patios, balconies, driveways – virtually any flat surface. They also tend to dry out faster than in-ground planting, so they require more frequent watering. But the portability and drainage they provide make grow bags a great choice for container gardening.

Benefits of Growing Dahlias in Grow Bags

There are several advantages to using grow bags for your dahlias:

• Better drainage – The fabric material allows excess water to quickly drain out, preventing overwatering. Dahlias are prone to rotting if their roots sit in wet soil for too long.

• Portability – Grow bags are lightweight and have built-in handles, making it easy to move your dahlias around to control sun exposure.

• Space saving – Versatile grow bags are perfect for small spaces like balconies, patios, and urban gardens with limited room.

• Weed control – When filled with a quality potting mix, there are no weeds to compete with your dahlias for nutrients.

• Aeration – Air can penetrate the bag from all sides, providing excellent aeration to the soil and dahlia roots.

• Contain spread – For large dahlia varieties, grow bags restrain the tubers and prevent them from taking over your garden beds.

Choosing the Right Grow Bags

When selecting grow bags for your dahlias, larger is better. Dahlias have tuberous roots that can grow quite large, so they require more room than many other flowers. Here are some size guidelines:

• For small/dwarf dahlia varieties, a 7-10 gallon grow bag is sufficient.

• For medium sized dahlias, opt for a 10-15 gallon grow bag.

• For giant dinnerplate dahlias, use 15+ gallon bags.

Make sure to choose grow bags with sturdy handles for easy transport. Thick, heavy duty fabric will last longer than thin bags.

Growing Media for Dahlia Grow Bags

The key to thriving dahlias is proper soil drainage and aeration. When planting in grow bags, avoid regular garden soil which may become compacted. The ideal potting mix for dahlias includes:

• Compost – Provides nutrients and improves drainage. Aim for 30% compost content.

• Coconut coir – Absorbs and holds moisture while resisting compaction. Makes up 40% of the mix.

• Perlite – Lightweight perlite aerates the soil and facilitates drainage. Add 10%.

• Peat moss – Retains moisture and adds organic matter. Comprises 20% of mix.

You can purchase premixed potting soils specifically for containers and add extra perlite for improved drainage.

How to Plant Dahlias in Grow Bags

Once you’ve selected the right grow bag and soil mix, follow these steps for planting your dahlias:

• Fill the grow bag 2⁄3 of the way full with moistened soil mix.

• Place the dahlia tuber in the center of the bag, 4-6 inches deep. The eye should face upwards.

• Surround the tuber with soil, leaving just an inch or two of space at the top.

• Water thoroughly until water drains from the bottom. This removes air pockets.

• Allow the soil to dry out slightly before watering again.

• Add a trellis or stakes as the dahlias grow for support.

• Apply a balanced liquid fertilizer every 2-3 weeks during growing season.

• Cut off spent blooms to encourage continual flowering.

Watering Dahlias in Grow Bags

Dahlias are thirsty plants, but also susceptible to rotting. To provide sufficient hydration without overwatering:

• Check soil moisture daily by sticking a finger in the top inch – water when soil is dry to the touch.

• Water in early morning to allow leaves to dry out during the day.

• Apply water until it drains from the bottom of the bag.

• Reduce watering if bags are soggy or dahlias show signs of rotting like yellow leaves.

• Increase watering during periods of drought and extreme summer heat.

• Consider using drip irrigation for convenient watering.

• Add mulch on top of the soil to maintain moisture.

Fertilizing Dahlias for Optimal Growth

In addition to consistent watering, dahlias need regular fertilizer to fuel plant growth and bloom production.

• Use a balanced liquid fertilizer with equal nitrogen, phosphorus, and potassium.

• Fertilize dahlias every 2-3 weeks from planting until buds appear.

• Mix the fertilizer solution at half strength recommended on label.

• Switch to fertilizing monthly once buds form to focus energy on flowers.

• Stop fertilizing 6 weeks before first expected frost to allow the plant to harden off.

• Incorporate slow release fertilizer granules into soil at time of planting for a steady nutrient supply.

Caring for Dahlias in Grow Bags

Dahlias thrive with minimal care beyond watering and fertilizing. Here are some tips for keeping your grow bag dahlias their healthiest:

• Inspect plants regularly for pests like aphids, slugs, spider mites. Remove by hand or use organic sprays.

• Immediately remove any diseased foliage or stems – dahlias are prone to powdery mildew.

• Pinch out the center shoot and side shoots to encourage bushy growth.

• Add stakes or a trellis when stems reach 12 inches tall to provide support.

• Remove spent blooms throughout season to promote continuous flowering.

• In fall, cut back foliage after frost then dig up tubers and store in cool dry place until spring.

Troubleshooting Common Dahlia Problems

Even when grown in ideal conditions, dahlias can still experience a few issues. Here’s how to troubleshoot common problems:

Leggy or spindly growth – Usually indicates insufficient sunlight. Move grow bags to the sunniest spot possible.

Few or no flowers – Can result from overfertilizing with nitrogen. Cut back on fertilizer and wait for blooms.

Wilting – Typically caused by under watering. Check soil and water bags thoroughly.

Insect damage – Treat pests immediately to avoid spreading. Don’t overuse pesticides which can harm pollinators.

Rotting tubers – Wet soil encourages rotting. Improve drainage and reduce watering if tubers are affected.

Overwintering Dahlias in Grow Bags

One downside of grow bags is that the entire bag can’t be moved indoors for winter storage. Here are tips for overwintering dahlia tubers planted in grow bags:

• After first frost, cut back stems to 6 inches above the soil.

• Carefully dig up the tuber clump and trim off extra soil.

• Allow to dry in a cool, dark place for about a week.

• Remove any rotted or damaged tubers. Healthy tubers will be firm.

• Pack dry, intact tubers in paper bags or cardboard boxes filled with shredded paper or vermiculite.

• Store tubers in a cool (40-50°F) basement, garage, or root cellar until spring planting. Check periodically for rotting.

• Discard the used grow bag – the moving and handling reduces its lifespan. Use fresh bags each year.

Key Takeaways for Growing Dahlias in Grow Bags

• Grow bags provide excellent drainage and aeration for dahlia roots.

• Use larger 10+ gallon bags for full sized dahlia varieties.

• A well-draining potting mix is ideal – avoid compacted garden soil.

• Allow soil to dry slightly between thorough waterings.

• Stake plants for support before they reach 1 foot tall.

• Fertilize regularly to promote flowering; reduce fertilizer in fall.

• Inspect for pests and diseases; address issues promptly.

• At season end, remove tubers and store in cool, dry spot until spring.

With the proper care, dahlias grown in grow bags will produce vibrant, long-lasting flowers to elevate your garden. The advantage of grow bags is it makes growing these stunning blooms possible even in small spaces. Just be diligent about watering and fertilizing, and your grow bag dahlias will thrive all season!