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anthony_toronto

How to promote root development in seedlings

anthony_toronto
15 years ago

This is year 4 growing from seed. Year 1 worked but did not start seeds very early or pot up enough. Year 2 and 3, started seeds early, moved seedlings from seed trays into standard 4-cell annual pots then into 4 inch pots (and some then went into 8-inch pots...in year 3 most seedlings ended up in 8-inch pots for the last month before set out, and were 3-4 feet tall when planted). I watered regularly (probably every 2 days, sometimes every 3 days), and applied a dilute liquid seedling fertilizer every 6 days or so. Plants were big, roots did a good job of filling up the pots, often growing out of the holes in the bottom of the pots.

For year 4, I still started seeds early (mid-march), moved seedlings to 4 inch pots, then to 8 or 10 inch pots. Just finished planting, and noticed that for the vast majority, root development was almost non-existant. I changed 3 things this year:

1. I used miracle grow potting soil instead of regular potting soil

2. I did not apply fertilizer (plants were still pretty lush and 3-feet tall when planted out in the last week...started 2-weeks later than last year, but plants were as big/bigger than last year).

3. I watered FAR LESS frequently.

Much of what I have read on this forum re. watering has seemed to indicate that the best way to promote healthy root development/root spreading was to follow the following steps: (a) water generously, (b) wait until soil dries up to the point that plant appears to be close to wilting, (c) go back to step (a). Wisdom seemed to suggest that by allowing the soil to dry out, the plant would stretch out its roots to try to find water, resulting in larger root balls. Result: instead of ending up with roots that filled 8 inch pots, I ended up with root balls smaller than my fist, for 3 to 3-1/2 foot tall plants.

Any guesses as to what might have caused this result? I did not check the makeup of the miracle grow potting mix, but even if it was phosphorous-free I would not have expected to see these results.

Given the underdeveloped roots, I worry that my plants will not be able to recover from the extensive sunburn that they are suffering. Regarding the sunburn, I have NEVER hardened off my plants before planting, and although I have notices a few white sunburned leaves or branches here and there, I have never experienced anything like I have this year, i.e. 3-foot tall plants that are sunburned from top to bottom after just 1 day in the garden. Is anyone aware of anything that would make plants overly susceptible to sunburn? weather when I planted this year was sunny (I planted in the evening, it was sunny the next day), but was no different than it was in my prior 3-years of planting.

Finally, my potato-leaf varieties seem to be hardest hit by sunburn/wilting (mostly wilting, after 1 day...3 or 4 bottom sets of branches are completely wilted, with 1 or 2 upper branches/growing tip still alive but not looking so great). Is this normal for potato leaf vs. regular leaf plants?

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