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I started these from seed indoors under a grow light. About two weeks ago I potted a few that were doing well, and now it looks like they're getting sick. The first image is arugula / rocket, and its leaves are getting gray and dry at the tips, almost like they're mineralized. They crumble to the touch. The sage in the second picture looks like it's starting the same thing.

My suspicion right now is the soil. It's about a year old, and I checked here beforehand and people said it should be fine and come back to life once rehydrated. Maybe something nasty set up shop and now it's attacking the plants?

My only secondary hypothesis is that the lawn rocks I put on top might have leached something into the soil after the first watering.

I'd like to know what's going on before the rest of my seedlings need potting.

edit: these plants are now outdoors on a table, with direct sun for about 8 hours per day. The soil was kept in its original bag, but it was outdoors in the shade.

enter image description here enter image description here

Tesserex
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  • Could you add a bit about where the plants are now - outdoors or indoors, and if the latter, do they still have an extra light... – Stephie Mar 20 '17 at 20:23
  • What make or type of potting soil was it that you used? Its just it looks quite lumpy with bits of bark and stuff in it... and if its a year old,where's it been kept in that time, i.e., indoors in its original bag or something else? – Bamboo Mar 20 '17 at 20:41
  • @Stephie I've made some edits. The soil is a miracle gro potting mix. I have noticed the large bits like hard sticks, and was a bit annoyed by that. – Tesserex Mar 20 '17 at 20:48
  • @stormy: I think your comments are enough to be put on an answer. I agree with _Leaf miners_ : the form seems much more made by a bug than some nutrient excess/deficit. The rocks could also be a problem. It is not so clear from image, but they could be alkaline, and if they are fresh cut, they will release a lot of reactive base. Which cause stress and so they help the miners. – Giacomo Catenazzi Mar 21 '17 at 13:36
  • @GiacomoCatenazzi The rocks are old, but I'll get them out and also get some fresh potting soil soon. – Tesserex Mar 21 '17 at 14:48
  • No one else has posted an answer so I went ahead and did what you suggested...thanks by the way! – stormy Mar 21 '17 at 21:52

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Get the rocks and chunks off the top of the soil. Is that pot full of just soil (potting soil) or are there rocks or gravel below the soil and above the drain hole. What I am seeing with BOTH plants is leaf miner damage. Are you sure you are using sterilized potting soil? Second problem is you are using too large of pots for too small of plants. These guys need pots no larger than 4" across and 3" high. Non decomposed organic matter such as sticks mean decomposers are busy decomposing and they need lots of nitrogen to do their job. Somehow you got a few insects to hang out in your pots. – stormy 23 hours ago

Leaf miners as well as a bit of salt build up...the tips of the first plant show this. I'd repot these guys in fresh potting soil asap in vastly smaller pots. Do not get potting soil with any added fertilizer or water holding gels, sponges! Use a tiny bit of OSMOCOTE 14-14-14. – stormy 23 hours ago

stormy
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  • Confirmed it just now - the second arugula started getting minor miner damage, and I pulled two live ones out of the leaves. Not sure what species, they were very tiny (maybe 1mm) translucent bright green larvae. Maybe they were just green because of the plant material inside them. – Tesserex Mar 25 '17 at 17:49
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It looks like your plants got too much watering and not enough sun.

What you should do is drain the water completely from the pot and put them in a clear (not too hot) place.

I'm not too worry about your sage, but the other one looks very worn out.

Jika
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  • That may be questionable advice - if the seedings aren't fully hardened off yet, they might get sunburn on top. – Stephie Mar 22 '17 at 08:55
  • They've only really had one watering in almost two weeks since repotting. They're on a table on my south facing patio. The only shade is one pillar in the morning and a tree in mid afternoon. – Tesserex Mar 23 '17 at 04:31