Transplant soil for hot and sweet peppers

Asked June 6, 2020, 5:21 PM EDT

Hi We like to grow both hot and sweet peppers. We have raised beds that we have planted for 40 years, in which we have incorporated silty river sand years ago, and ground up leaves each fall. We generally use Peter Chan's #2 fertilizer mix under the plants (sometimes we use 16-16-16 in the soil around). We started seeds in March in 2 x 2s, eventually transferring them to to 4 x 4s using G & B Raised Bed and Potting Mix, thinking that it should work well because the name says "raised bed". The seedlings in the 4 x 4s just sat there or grew slowly. They put them in the sun when we could and took them inside at night. The only thing that I can figure out is that the soil is too wet. Part of my evaluation was that we had a couple seedlings that lagged the others so we kept them in the 4 x 4s, hoping that the roots would develop. They did poorly. When we put them in the ground, we broke off as much G & B as we could without harming the roots. The plants are now flourishing. What I am asking from you for is a tried-and-true recipe for transplant soil for both hot and sweet peppers for the 4 x 4s, that will eventually take to the soil in the raised beds and not inhibit root growth*. Our eval of G & B is that it worked okay for transplanted tomato seedlings, and just okay for basil (basil survived but did not flourish). Poorly for peppers (see above), summer and winter squashes (the leaves turned yellow), and marigold seeds (they didn't come up). Thank you. *PS Side Bar: We tried using Miracle Grow Moisture Control Potting mix a few years ago. It worked fine for flowers in pots, but we had trouble getting the roots to take to the soil in the raise beds. The roots preferred the Miracle Grow. The bag said not to use it in the garden or put it in the recycle bin. I called the company and asked them what we were supposed to do with it. They said to put it in the garbage. We no longer use Miracle Grow potting mixes.

Multnomah County Oregon

1 Response

Thank you for choosing Ask an Expert for help with your vegetable starts. And it’s great to chat with someone that remembers Peter Chan’s work, as well.

There’s a lot to unpack here, so I’ll just start with some observations.

Critical for growth of these warm-weather vegetables (basil, tomatoes, peppers, and squash) is warm temperatures. Recommended times of planting are averages, and can’t take into account yearly variations. For example, In March this year, the average daytime temperatures were below 55 degrees. Even in April, the average daytime temperature never went above 60 degrees. Seedlings spending the day in these cool temperatures do get sunshine, but can’t do much with it.

The plant isn’t actively growing, and it isn’t using a lot of water, resulting in a too-long-wet soil. This isn’t good for the roots, regardless of the type of soil. And inexpensive soil thermometer or heating mat can help guide you through temperature variability.

Across the bagged soil industry, it is unusual to have fertilizer included in the bag. There may be a small “starter” shot, to get plants off to a start, but not enough to do much feeding. [The Miracle-Gro Moisture Control Potting Soil is one of the exceptions. It contains enough plant food to carry plants through a season.]

What this means is that three or four weeks after germination the plants should start to get fed. You don’t mention doing that. This could be partially to blame for a slow start of the seedlings.

Personally, I start seeds in a seed starting mix, because they are very well-drained mixes, to keep seeds moist, but not soggy. My personal preferences aside, many seed starting soils and potting mixes work for many people. Over-waterers need an open, fast-draining mix. Forgetful gardeners do better with a water-holding soil. Truly, there is no “best” or “right” mix.

For more on seed-starting, see here: https://extension.oregonstate.edu/news/save-money-starting-vegetable-seeds-home and for great information on vegetable growing, see Oregon State Extension Service publication Growing Your Own, here: https://catalog.extension.oregonstate.edu/em9027

Have a good gardening year,