Some of the very first dahlias I grew.
After growing lots of dahlias over the past few years I’ve come to the conclusion that it is much easier than I ever dreamed. They are the beauties of fall for sure. They can become quite addictive if you aren’t careful–you’ve been warned! Once you provide what they want, they produce like crazy. I have listed below the steps we follow here on our flower farm in winter hardiness zone 7.
- Plant tubers once the soil has warmed in spring for best rooting.
- Dahlias need full sun.
- We plant one single row in a 24” beds, 12” apart in the row. Dahlias are actually very robust growers and I’ve found when given room to stretch their wings keeps them in better health.
- Excellent drainage is a must! Deeply prepared soil with compost and/or composted manures is excellent. I mix dry fertilizer in at this time.
- We plant the tubers according to directions and lay strip of irrigation down the bed.
- A 1”-2” layer of compost as a base for mulch, then top with 3”-5” of mulch (we use leaves).
- We water at planting time and don’t water again until we see green coming.
- Once growing, dahlias love water. Give a deep watering once a week- we run it slow and low overnight.
- We cut the central stem out (the first stem) at ground level to encourage lots of branching with nice size stems.
- We install flower support netting with serious stakes before they reach 20”. Stakes are closer than other beds- like every 6’-8’ feet.
- In a perfect world I would foliar (spray on foliage) feed dahlias with Neptune’s Harvest each week. But ours get it more like monthly. We also run it through our irrigation monthly.
- We harvest the stems when they are 1/3 to ½ open. We make the cut at ground level. Doing this encourages more sturdy stems to sprout and grow and it also helps to keep the plants from becoming overgrown and difficult to manage.
- Our harvest buckets have a GerbPro tab in 1 gallon of water to kill bacteria, leave stems in at least for 4 hours and up to 72 hours. From the GerbPro tab water we move into Bulb Fresh Cut Flower Food.
- Dahlias love refrigeration. We put in cooler for at least 12 hours before selling or using in arrangements. It seems to help with vase life.
- While in zone 7 we can leave dahlia tubers in the ground over winter we usually dig them to save them from vole damage. The winter is the time the voles really go after them.
- Digging and storing tubers: resist hosing off the soil- it can lead to rotting. We shake off the soil, do any dividing needed and store in peat moss in a cool dry spot for winter.
Dahlias will make fall feel like spring all over!
Lisa Mason Ziegler is a commercial cut-flower farmer in Newport News, Virginia; she lectures and writes about organic and sustainable gardening. You can email Lisa at firstname.lastname@example.org, call her at 757-877-7159 or visit her website www.shoptgw.com .
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