Moving seedlings from hydro to out of doors

Gordon:

Several problems militate against successful transplantation from hydro or aquaponic systems to the out-of doors:

1. The roots which develop in hydro systems have a more brittle nature, are less densly branched, poorly suited for a transition to field soil. THey have grown in adaptation to a more watery substrate. You might more successfully transplant the seedling to a light weight potting mix, which you could then harden off gradually, leading me to discuss problem number:

2. Transplants pulled from an aquaponic substrate and placed directly in the field would suffer from sudden exposure to the harsher conditions, wider spacing, lower temperatures, lower humidity, higher wind speeds, lower moisture levels at the roots,much stronger sunlight. Gradual "hardening off", accomplished by gradually exposing the plants to more and more rigorous conditions(you wouldn't want to spend a 12 hour day on the beach in the sun on your first day at the shore)will produce a plant that will not go into shock.

3. In general, transplants should be individualized, as small as possible, and should be timed so as to be potbound enough to be needing water about every other day, at the time when you are intending to plant them out. Keep them moving with fertilizer, be sure that soil temps are adequate for the plant you are setting out. Feed regularly during hardening off, lest the plant sacrifice nutrients in it's oldest tissues to feed the new growth.

Fred

Gordon -

When starting peppers directly in the gravel, I use a process similar to what you would use in a flat of potting mix. Drag a small furrow, and space closely (this will allow you to choose the healthiest plants for transplanting later), then just pinch the gravel back over the seeds. Does not use much bed space, but allows for separation of several crops in this small area. When about 2" tall, move into spacing of appx. one square inch per plant.

Fred responded:

"2. Transplants pulled from an aquaponic substrate and placed directly in the field would suffer from sudden exposure to the harsher conditions, wider spacing, lower temperatures, lower humidity, higher wind speeds, lower moisture levels at the roots,much stronger sunlight. Gradual "hardening off", accomplished by gradually exposing the plants to more and more rigorous conditions(you wouldn't want to spend a 12 hour day on the beach in the sun on your first day at the shore)will produce a plant that will not go into shock."

We agree entirely. Actually doesn't matter whether plants are started in the system or in potting mix, but hardening off is a necessity when considering moving to outside environments. Any plants grown under cover will not have had the opportunity (necessity) to strengthen for outside weather conditions. When we were growing bedding plants for spring sales, we moved them into potting mix in 4-packs or pots, left them undisturbed and shaded for 24 hours, then moved them into a cold frame with roll-up sides for gradual hardening off before being market-ready. I used the same process for peppers I planted in outside gardens for our pepper-sauce side business.

We found having started in the system, then being watered from the fish tanks during this preparation time helped us to have successful, healthy plants that handled well for the ultimate customer and showed little transplant shock for them.

Gordon - It's not the temperature difference that will affect the plants, but rather wind and rain (or overhead watering) that will create the biggest problems. In this respect, it's no different whether you grow in soil, gravel, or any other media indoors. When you take your plants outside, they must adapt to a whole new set of environmental conditions, and I didn't mean to infer that you hadn't any experience with this.

The advantages to growing seedlings in the gravel beds are, in my opinion:

1) Overall health of the plants - having germinated and grown in a system where there is no stress from lack of water, where temperature is relatively stable, and having a constant supply of "slow-release fertilizer" to supply nutrient needs.

2) Reduced transplant shock - because the gravel is easy to loosen before removing seedlings, very little damage is done to the root system.

We've had great success moving seedlings from one grow bed to another within the greenhouse. I've transplanted basil from my seedling bed to grow-out beds in the middle of the summer, during the heat of the day, because that was the only time available.

We've grown dry-rooted seedlings for other growers, and had them transported for planting into their grow-out spaces with near perfect results (Lemon Verbena, for example, as well as tomatoes).

I would think it possible to directly transplant seedlings if you were to simulate outside conditions. Perhaps a strong fan creating sufficient air movement to strengthen stems to the point where a strong wind would not cause additional stress to the plant. Would certainly be worth exploring.

Paula