This is the first year I'm growing my vegetable seeds in standard greenhouse trays and inserts. As a result I wound up getting some inserts I thought were something else and I'm trying to figure out if I should use them or not.

Instead of getting deep 606 or 32 deep inserts I wound up getting 3601 inserts which have measurements of 2.23" L x 1.94" W X 2.23" D and can hold 7.32 cubic inches of soil. The amount of soil is similar to a 806 deep cell which is what's commonly sold in nurseries around here.

I'm starting my seeds in 98 cell trays. I have 3" sheet pots that I plan to transplant most of my tomatoes to but wondering what, if anything, I can use the 3601 inserts for so I don't have to buy additional inserts this season.

Some of the things I'm starting from seeds include:

  • another batch of tomatoes that will grow for 2 weeks less than my main ones
  • peppers
  • eggplants
  • zucchini
  • melons
  • cucumbers

Can I get away with using these wide shallow inserts or should I just get something deeper? What are good uses for these inserts?

3 Answers 3


Those are pretty shallow for cucurbits, especially melons, in my opinion, but I haven't tried it personally (so you can always experiment). Melons tend to grow deep taproots, and they're initially much larger seedlings than tomatoes. So, that's why I say that. It'll likely be a bigger problem with watermelon than other cucurbits, though, if what people say about starting watermelon indoors damaging the taproot and stunting the plant is true. I'm trying several large watermelon varieties in 20 fl oz foam cups, currently. So, I can tell you how that goes later, if you like.

It should be fine for tomatoes. It can work for peppers and probably eggplant, but I would personally plant them in bigger containers to start with, since peppers can tend to get a little stunted for a while when you transplant them, and the less transplants the better.

Whatever you do, make sure you have enough light. Plants are more forgiving with more light, often. I think they're more forgiving when they have enough potassium, too. If you have enough light and potassium I'm guessing the amount of soil won't matter as much.

  • Some of what I read on the subject is conflicting. Most though does say that transplant size doesn't effect total yield or final plant size once transplanted to the garden. Some suggest that larger transplant size may increase early yield but not total yield but only when the larger transplants are older. Other studies show no difference. Here's one reference for peppers I found where there wasn't much difference between 72-200 cell sized transplans msue.anr.msu.edu/news/transplant_trays_does_cell_size_matter Commented Mar 26, 2015 at 12:55
  • The studies probably differ because the gardeners probably performed those tasks differently. For instance some might have planted them more deeply so that the stems would grow more roots, or they might have given them more or different kinds of light than others. The soils probably differed in nutrients and consistency. The climates may have been different. They may have used different fertilizers or soil amendments. There may have been different soil microbes. Local pollution may have differed, as with the minerals in the water supply. Gardening studies should be viewed in context. Commented Mar 27, 2015 at 0:05
  • Then there's soil PH, and I'm sure a large list of other things. Personally, I think the results are going to be similar, as long as the plants are healthy and equally mature. The length of the growing season is probably the major factor. Commented Mar 27, 2015 at 0:10
  • At least for peppers and other solanaceae fruits. Cucurbits may differ. @OrganicLawnDIY Commented Mar 27, 2015 at 0:11

Peppers usually grow fine when started in shallow containers. Melons typically do not, as Shule pointed out- they grow deep taproots. Cucumbers and Zucchini also will grow a deep taproot, but I believe they're a bit slower than melons, so you might be able to get them to sprout in the shallow container, then transplant them.

Many herbs and flowers don't require much root depth, and something like alfalfa hardly requires any at all. Be sure to keep your baby plants fertilized and very well lit- even near a window I use a grow light when I'm sprouting.


Sprouting seeds/starts should take very little soil/space. 2X2X2 is just a bit large for starts. Ok to use just have to watch the moisture. Warm soil (60 degrees F), moist not wet, little or NO fertilizer, light when seed leaves emerge. If they get too spindly then you don't have enough light.

Transplanting in my mind makes for stronger plants. Sure you won't see much in the transition because the plant is putting out a new root system, but I've never seen a reduction in yield.

To plant seeds in pots you are part of the equation. Planting seeds in a garden is totally different. Don't worry about yield, worry about keeping a plant healthy, vigorous.

Planting seeds or small plants in pots, it is critical to keep the amount of soil SMALL. Otherwise keeping the moisture correct is pretty tough. Too much wet soil and you'll lose your start to damping off as there is nothing to soak up the water and dry the soil before fungus/decomposers take over.

A larger garden out of doors will have checks and balances. To start or grow anything in pots means you are the one in charge, not nature. Transplanting is stressful but just like us, we need a bit of stress to flourish. The right amount of stress will make a stronger plant (everything else being equal). Don't worry about transplanting. I think these 2X2X2 will work fine as long as you monitor the moisture. You WILL have to transplant but make sure that the next pot is no larger than a 4" pot. The next will be either 6" or 1 gallon. Melons should be in the ground after that, peppers will be fine in 1 - 2 gallon sizes. Tomatoes do best transplanted into 7 - 10 gallons or the ground. If you can get starts transplanted into the garden soil sooner, even better.

  • To clarify, as I mentioned in my question, I'm starting the seeds in 98 cell trays. Most of what I'm starting from seed will be transplanted from those 98 cell trays to 3" pots. From there they will go into the ground. I'm asking if I can use the 2x2x2" pots for anything in lieu of the 3" pots because I already have them and they save on soil and space. Also details on which plants would work in them and possibly how long they can be kept in those pots before planting out in the garden. Commented Mar 27, 2015 at 14:33
  • I'm saying go ahead and use them! Transplanting is good if we are trying to be in charge by using pots. I think transplanting seedlings from tiny pots works much better than risking planting seed straight into the ground. I think that 2X2X2 pots are actually a bit big for some seed! Not too small. Please use sterilized potting soil, NOT garden soil. Very little or no fertilizer. Fish fertilizer is good at this point. Otherwise, I know your know this stuff!! Grin...
    – stormy
    Commented Mar 28, 2015 at 21:46

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