Transplanting question

[GaryStPaul]

My seedlings are just about at the first true leaves stage. Is there any reason not to transplant them into the containers they'll remain in until planting out in the garden--in my case 18oz red party cups with drainage holes-- 3 1/2" diameter, 4 1/2" deep? Put differently, is there any benefit to two transplantings (first into a smaller pot, then the 18oz cups) before final setting out? What's the best practice here?

TIA,
Gary

[ScottinAtlanta]

Sounds like a huge cup and a waste of potting mix. I use 9 ounce cups and they get 18 inches high in them before I transplant them out. Also good to use transparent cups so you can see root development.

[Doug9345]

The advantage of two transplants is that you get a second opportunity to plant the tomatoes deep and thus develop a more substantial root system.

One way I accomplished the same thing is to transplant them into the bottom half of the cup and fill in with mix as they get taller. The disadvantage of that happens when the lights aren't directly overhead. The sides of the cups cast shadows.

[Barbee]

I only pot up once. I wait until the plants get 2 sets of true leaves then they go into 4 inch pots where they stay until they get planted into the garden. Have never noticed a problem with it.

[KarenO]

Us northerners need to keep our seedlings inside longer so if cost of potting mix is OK with you and you have the space, the answer is you can transplant them into whatever size pots you wish. There is no advantage to transplanting them twice, in fact their growth is checked with each transplant and being rootbound does them no good either. If you want to transplant a two leaf seedling into a five gallon pot, go ahead, it's your dirt
Karen

[Durgan]

http://www.durgan.org/URL/?FROBQ 14 April 2011 Transplanting Tomato Plants Tomato plants were placed in larger pots. The larger pot has a coffee filter insert to contain the roots somewhat, and to prevent soil from leaking out of the drain holes. The lower leaves are cut off the target tomato plant. The plant is placed deep in the large pot. Roots will form from the portion of the stem that is buried. The plant is watered from the bottom, which is my preferred method. Depending upon growth, one more transplant may be necessary, since they will not be place in the outdoor garden for about six weeks.


I keep on moving to a larger pot as the plants starts to become root bound. Sort of trial and error until time to place in the outdoor garden. I am most careful and try not to disturb the root system.

[luigiwu]

Durgan, what are you using in your "soil" mix?

[Cole_Robbie]

The benefit of transplanting is that the roots will fill your media space more densely. They grow to the edge of the container first, and then fill the rest of the space.

[Durgan]

Originally Posted by luigiwu

Durgan, what are you using in your "soil" mix?

I make my own soil each year. It varies in composition from year to year but this is typical.

http://www.durgan.org/URL/?IEVCS 11 September 2013 Seedling Soil
Seedling soil for the 2014 season.The underlying nutrient soil was the compost heap brought in this Spring supplied by the city. It was modified using some knowledge and information from previous subjective experience.Ingredients added to the basic underlying compost was, coconut coir, mason sand, some garden earth, wood chip shavings, a bit of fertilizer 10 10 10. My mental process was this. Coconut coir for moisture retention. Mason sand to inhibit coagulating of the basic compost. Garden earth to supply a few microbes. Wood chips shavings for aeration and to determine how well the products are mixed, since they are easily seen.
The subjective quantities selected were mixed thoroughly on the compost pile using the Honda FG110G rototiller. The finished product was stored in 20 litre buckets and closed with lids tapped into place with a rubber hammer. A total quantity of about 400 litres was obtained. Holes were drilled under the lid lip to allow air in.

[GaryStPaul]

Thanks, everyone, for your helpful replies. There seem to be two points of view here: (1) more transplanting checks root growth (not good); and (2) more transplanting stimulates root growth (good). Folks seem to be successful either way.

Question for Durgan: In your 14 April 2011 pics, from what size container are you potting up into the larger container with coffee filter? I assume the latter is your second transplant from the flat or whatever you used to germinate the seed (the third being into the final tub).

Thanks,
Gary

[KarenO]

I think transplanting checks top growth in favor of root growth. This can be beneficial or not, depending on a number of factors.

I grow mainly midseason varieties outdoors in my short season zone 3 garden. The way I can do this successfully is by planting out large well grown transplants (24")either already blooming or near to blooming at the end of May. This is how I have found I can grow these 75 day+ tomatoes in my garden and get ripe tomatoes before frost. I am a home gardener only and so that factors in. I grow about 50 plants in my own garden and start a bunch more to give away as well. I have found that the minimum size pot that will support my 24 inch seedlings is 16 oz but bigger is better if you have the space and cost for high quality potting mix is not prohibitive. I worry less here about roots than our southern counterparts as we do not have to battle RKN or most other disease issues that our cold winters do not allow to survive up here. ( the only benefit of a cold winter is the natural pest control it provides). My goal is not to check the top growth because I need those early blooms to set fruit.
When I plant mine out in warm soil, I plant them deeply at that time and roots do develop all along the buried stems once they are in their final position so my point is it doesn't need to happen in a solo cup, it will happen in the ground. They take off like nobody's business and that is how I have learned to grow more than the standard early varieties up here.
The point you make about there basically being many different ways to go about things and still have success is very true. But I cannot grow tomatoes up here the way they are grown in the southern states and neither can you in Minnesota.
Karen

[bower]

Like Karen, I do better with a big sturdy seedling that has at least 6 to 8 weeks of growth before planting. I've tried different routines of potting up gradually and found no benefit just more work for me and more stress to the plants, which quickly get rootbound in a 9 oz or 12 oz cup. I do mass germination and transplant to cell pack until the first set of true leaves, then straight into the 16 oz cup, which is the right size for the number of weeks root growth without getting rootbound or stressed. I use a little bone meal in the potting mix to encourage strong root growth, and water thoroughly but only when needed.

[GaryStPaul]

Karen and bower, thanks for sharing. I think I've got what I need to know for my Minnesota conditions!

Gary