6 inch would be the best. try not to start so early.try 8 weeks total time.

I would suggest some 16 oz. plastic drink cups with drain oles in the bottom of them. Used by many and they allow you to transplant the too-tall plants deeply so they can develop a better root system.

And I agree, next year don't start them so early. 6-8 weeks before planting time is plenty and will give you much better transplants.

Dave

The pots they are in right now are quite a bit wider than the 16oz cups, but not as tall. If I pot them up I will have to go with something bigger than they are already in.

I know I started early. But I am in Wisconsin - we have a short growing season and I wanted to try and get a head-start. This is a pic from a week ago, they are a good bit bigger now, but a similar proportion.

Yeah I realize they are wider but it is the depth you are after. Depth is more important than width.

They can go into the 16 oz cups only 1/2-3/4 full of mix and then as they get taller you can add more mix - bury more of the stem so more fibrous roots can develop.

The point at this time is to create a substantial root system not top- growth. Roots that can easily support and feed them when planted outside.

Dave

Ok - Thanks. I thought I was doing them a favor getting these nice fat pots for them. Next year I will definitely go with the tall plastic cups. As you can see from the pics there is room at the top. If if dump off the quartz grit (1/4 inch layer) and top them up to the brim with mix, they will get another 3/4 inch of depth and have dirt up past the cotyledon leaves. Maybe that will hold them for this year? Or maybe I can rig up some sort of "collar" extension to raise the height of the pots. Thanks for the advice.

Hey Dave - what do you think of this compromise? I cut off the bottom inch and a half of 16oz cups, cut a slit down the side and then tacked it together again with a piece of duct tape. I snipped off the bottom 2-3 leaves from the plants and piled on more potting mix. It turns my 4" pots into 7" pots without the stress of transplanting.

{{gwi:42849}}

I like your idea, I have the same problem. I live in MN and started mine to early also. How did it work out for you? I think I may do the same but just do it with the solo cups because thats what mine are in right now. Thinking I can cut the bottom off and fill a new one with dirt then sink them together.

If you have a number of plastic 2-liter bottles or cardboard 1/2 gallon juice cartons, they're quite wide, if width is necessary. Cut the tops off, at whatever height you need. [And if more width isn't necessary, you can also use narrower plastic bottles.]

Thinking I can cut the bottom off and fill a new one with dirt then sink them together.

Leah, I'm not sure I understand your response. The point of using a taller container is that when you pot up, the current roots can be placed at the bottom of the new container. Snip off the lower leaves and add soil around the bottom few inches of the stem. Additional roots will grow from the currently-above-ground stem, resulting in a larger root system.