There's always grow bags (and pots)

Teddahlia

We have in recent years grown some dahlias in pots. A 15 gallon pot is ok for 4 foot flower but we used mostly 20 gallon black pots (new ones cost $10.00) and grew them to heights comparable to those grown the garden, They do much better if the sides of the pots are shaded and we had our best results in our annuals flower garden and the annuals were planted next to the sides of the pots. Staking the tall plants(7 feet tall) in pots is challenging and despite using some t posts. the taller ones fell over in the late part of the season. Planting soil for these pots consisted of recycled potting mix for the majority of the pot and about 8 inches of new(expensive) potting soil on top. Fertilizing plants in pots is also quite different as we use an "osmocote" type fertilizer(Haifa multicote14-14-16) and it is 3-4 times as expensive as our granular fertilizers used on the garden. It is supplemented after 6 weeks with another dose as it poops out a bit at that time. Watering was done by hand when I hand watered our hanging pots and containers every day(almost every day as it sometimes rains).
Do you move the grow bags around much? We occasionally move the pots. Is that the advantage of the grow bags in that you can move them? Or is the advantage that you can grow the plants on top of concrete or in places not able to be tilled? Our pot grown dahlias intention was to display them with lots of other flowers around them. By the way, many of the other flowers are also planted in pots, including several 20 gallon pots.
Note the dahlias in the pots are just part of the flower garden.

blown_dry

Teddahlia I understand the advantage with grow bags is that the breatheable material is friendlier to roots and the roots don't keep growing around in circles until the plant is rootbound. Also they are collapsible when not in use. May also be lighter than a comparable pot. Certainly it's easier for people to transport and store 100 gallon grow bags than a comparable container. A local farm grows all new acquisitions in grow bags for at least a year so they can check for disease and other issues before growing the stock in their fields.

calico20hill

I grew my "overflow" of plants in 15 gallon grow bags. One thing I Liked was that these were so heavy my plants did not need staking..and I really didn't have a way to stake them so that worked. The "organic garden soil" we bought had way too high a proportion of sand in it so I think the nutrition level was rather low.They did drain well. All and all it was the best thing we could do with the extra plants and I will use them again this year but will add a heavier soil mix to the sandy soll and of course fertilize a bit more. The tubers were a bit fewer in number but easily harvested out of the grow bags.

JessieC

calico20hill I also used the grow bags for “overflow” plants, and also for pot tubers. I had three or four small pots tucked in a few of the bags. I will try adding some granular fertilizer this year. I mixed my very rich garden soil with some potting mix to lighten it up a bit. For stakes, I have a few metal obelisk type things that worked well. You can’t see the green ones that I scored at the Habitat Store here. They’re tripod structures with a ladder that is perfect for threading twine through the plants. I also snaked a drip line around the bags, which you can see in this pic. They needed a bit more care than the dahlias in the ground, but when it came time to harvest tubers, it was a breeze!

ETA this was taken late October, so things look a little dry and neglected. They really did very well in the bags!

Krista

I grew in 15 gallon grow bags that were very heavy and sturdy feeling. Each bag got one tuber and one 5’ wooden stake and I didn’t have trouble with any plants falling over.

I planted in a blend of Sungro potting soil and Tueful compost. Learned this year that Tueful is too hot and hasn’t been rotted for long enough. Ended up with dark spots on the tubers of a couple varieties that likely had more compost mixed into their bags than others.

Fertilized with Alaska Fish because that’s what I had on-hand and water soluble Kelp fertilizer. I was in the same boat as calico20hill “The tubers were a bit fewer in number.”

I’m going to spend a bit more on my compost this year and maybe explore some new fertilizers!

Teddahlia

Did you really mean 100 gallon grow pots? I suppose you meant 100 one gallon grow bags?

blown_dry

Teddahlia Nope, they are basically a raised bed for $15.99.

https://www.google.com/search?q=100+gallon+grow+bags

The pot farmers use them a lot and a quick search revealed up to 1,000 gallon sizes.

katyaker

"There's always Grow Bags"

I need to get a t-shirt with this on it!

bloomhjelm

katyaker "There's always Grow Bags"

I need to get a t-shirt with this on it!

I will spend more time in Canva and work on this, haha. This is my first draft.

bloomhjelm

Fertilizing plants in pots is also quite different as we use an "osmocote" type fertilizer(Haifa multicote14-14-16) and it is 3-4 times as expensive as our granular fertilizers used on the garden

One of the best pieces of information I got last season was a grower sharing their fertilizer and organic pest control schedule week by week. Understanding what different containers and areas need is another layer of complexity.

Organic pest control really can't be frequent enough in my wooded area it seems. I tried something new with a peppermint oil based spray. It made the dahlias smell like mint chocolate chip ice cream and brought all my kids outside. Was it effective though? Unlikely.

calico20hill

I''ll be getting garden soil from a different supplier this year (Just doing the pea test on it now) and it is much denser. I think mixing last years soil with the new soil will work much better all round. I need a new big container of osmocote, too.

Krista

calico20hill Which Osmocote do you use, Flower & Veggie?

calico20hill

Krista Ha, I don't remember but lead me to the fertilizer row at Portland Nursery and I will pick it out fast enough!

katyaker

bloomhjelm
That is awesome! I would totally purchase a t-shirt with that graphic on it.

Teddahlia

On Dahlia Talk, an experienced nursery man who grew plants for landscaping, recommended 14-14-14 Osmocote in the 4 month release formula and it comes in a 50 pound bag that costs between $100- to $150-. He gave a 50 pound bag to his brother as a Christmas present. I am sure smaller sizes are available at retail stores. We use Haifa Multicote 14-14-16 in 4 month release, and last year it was about $75- . It uses the same technology as osmocote and has minor elements as part of the formula. I expect a price increase as it is made in Israel. Haifa is the largest fertilizer company in Europe. I bought a 12.5 lb box of Miracle Gro at Costco for $25.00 and it is a good back up fertilizer if I cannot find my Plantex (or Jacks is good too) 20-20-20 greenhouse fertilizer. The Miracle gro has more nitrogen (24%) and I bet it would not be as gentle on greenhouse plants but it is about 35% less in price. I have used it before and it worked OK. For sure I will use it on flowers other than dahlias and I will always remember the old TV commercials for Miracle Gro done by the character actor James Whitmore. He was one hell of gardener😳.

Krista

Teddahlia Thank you, I know this isn’t the most enthralling topic but I super appreciate knowing what folks are currently using. It helps narrow the list of options. I may consider giving the fertilizer a whirl that came up in the most recent Dahlia Talk this season too.

blown_dry

Krista It's an important topic! If you type "fertilizer" into the search bar up top there are lots of results.

bloomhjelm

katyaker

Can I make my attached images in these threads smaller? On desktop it's HUGE! Sorry.

NCDahlia

I have used grow bags for dahlias they do OK but need excessive watering. I have grown pretty much any veggie u can think of in the 100 and 50 gallon grow bags. I also have 90 blueberry bushes all growing in 25 / 30 gallon grow bags and they thrive. Bc shallow root system also get air pruned constantly in the bags.

I have ordered 400 1 gallon pots (nursery pots) and dahlias will grow in those with same soil I've used over year. Hardware cloth on bottom so no voles. The 2 gallon pots had the holes on the sides and about 1/2 inch above the bottom don't want standing water.