This is probably a stupid question, but I'm just starting to experiment with
growing from seeds. All the seed packets I have provide specific depths to
plant the seeds under the soil, so I assume I shouldn't mulch over them if I
plant directly in the ground (as opposed to containers or flats). I do want
to mulch around the plants eventually, so when is the most appropriate time
to do that? Does it depend upon how tall the seedlings are, what type of
plant, etc.? For example, I just planted sunflowers, zinnias and cosmos.
All three of the packets say to thin and separate when the seedlings stand
about 2 inches tall. Would it be OK to mulch at that point, or should I
wait until they get taller? Thanks in advance for any assistance.

Cheers,
Rhonda
Alexandria, VA
Zone 7

*********
It's a rave, darling, a mad rave!

Natty_Dread wrote:
This is probably a stupid question, but I'm just starting to experiment with
growing from seeds. All the seed packets I have provide specific depths to
plant the seeds under the soil, so I assume I shouldn't mulch over them if I
plant directly in the ground (as opposed to containers or flats). I do want
to mulch around the plants eventually, so when is the most appropriate time
to do that? Does it depend upon how tall the seedlings are, what type of
plant, etc.? For example, I just planted sunflowers, zinnias and cosmos.
All three of the packets say to thin and separate when the seedlings stand
about 2 inches tall. Would it be OK to mulch at that point, or should I
wait until they get taller?


It should be OK to mulch at that point. As long as the mulch doesn't
cover the true leaves of the plant. The purpose of the mulch is to
reduce weeding requirements, so before applying the mulch, kill all the
weeds around the plants. This can be done by simply stirring the soil
with a small trowel. Just stir the top inch or two of soil away from the
plant. Near the plant stir the top half inch or less, trying not to
disturb the plant's established roots.

One of the definitions of a weed is a plant that you don't want that is
really persistent. If such a weed seed has germinated (not necessarily
emerged from the surface), it is likely to grow through your mulch, so
stirring the soil will damage the roots of the weed and kill it. The
mulch will keep the ungerminated weed seeds deep so they won't
germinate. Most weed seeds are small and there's a rule of thumb that
seeds won't germinate if they are buried more than seven times their
maximum dimension (maybe it's their average dimension, I'm not really
sure, but at any rate it's just a rule of thumb [which means that there
are lots of exceptions to the rule]). If you stir the soil too deep, you
will bring up weed seeds that wouldn't otherwise germinate, so shallow
cultivation is best. When cultivating, if you see little white threads,
those are the roots of weeds that have germinated, but haven't emerged
yet. Exposing them to air so that they dry out kills them. This doesn't
work well on cloudy days after a lot of rain.

I plant sunflowers and zinnias 9 inches apart, and it works well, so
that's a good way to thin them when they're large enough. When thinning,
start with the healthiest plant at the end of the row, then find the
healthiest plant at your desired thinning distance away, within maybe
50%. You don't need exact spacing. The healthiest plant is not
necessarily the tallest, but rather the one with some combination of the
thickest stem and the best looking leaves. Thinning is the hardest part
of gardening for a new gardener: one never likes to kill the plants they
planted in the first place.

Cosmos seems to come in two varieties: early and late. Every time I
plant cosmos about half of them bloom. The others just form a large
green plant. Later in the summer the blooming plants start dying and the
green plants take over the blooming. So don't expect them all to bloom
at once.