Starting Dahlia Tubers Indoors - 1 Gallon Pot Inventory - March 2026

Dahlia season is coming fast.  Or, at least it is feeling like it is coming fast to this gardener.  The past two seasons, I've started my tubers indoors, well ahead of the last frost date (around Mid-May here).  In 2024, I started them in early May.  There were only six tubers to start.  How quaint.  Looks like I ended up with twelve total.  I planted them outdoors in June 2024.  

Last year, in 2025, I also planted them up starting indoors.  In early May.  By mid-May they were showing signs of growth.  I began to harden-the-off towards the end of May and (like 2024), planted them outside in the beginning of June.  Last year, I also pinched them all back to try to get bush-ier growth.  

My plan for 2026 is to follow a similar trajectory, but I'm thinking I can start them even earlier.  Like mid-April.  The last frost date varies around here, but generally is between the middle and end of May.  I'll watch the soil temperatures and forecast and hopefully have a good year to get these in the ground before the end of May.  Even with a June 15th planting date last year, I had A TON of blooms. 

But...that brings me to the planning challenge.  

In the recent post about the Saint Martin dahlia tubers (4 of them) from Costco, I mentioned that I was (back-of-the-napkin) up to 25 new tubers for this growing season.  That's 25 pots just for the new ones.  They need to start in the basement.  Then, when the time comes, move up to screened porch before going outside. 

That means I need a materials list:

1.  1 gallon pots.

2.  Plant tags.  Last year I used coffee stirrers.  

3.  Coffee filters.  For the bottom of the pots.

4.  Potting mix.  

5.  Enough 'trays' to hold the pots

Let's start with pots.  I kept a bunch around from last year and just went and did an inventory.  Here, below are 19 that I've kept on the Compost bin all season:

And, thanks to a Winter sale, I have 15 new ones:

19 + 15 = 35 on hand.

Last year, I planted out 21 dahlia tubers by starting them indoors in pots.  And, I *KNOW* that a number of those tubers (if they made it through Winter - *KNOCK ON WOOD*) are big enough to be divided.   Even if I didn't divide any of them, we're talking 25 (new this year) + 21 (stored from last year) = 46 pots to start them indoors. 

I'm thinking 55 is the right number.  EEEK.  55 tubers?!?   I'll have to go get 20 more pots in the next few weeks.  Along with a couple of BIG bags of potting mix.  And...some coffee filters.  And, some plant tags.