Hopefully you can shed some light on this mystery. Mediterranean herbs are perforce suited for lean sandy soil, hot temps, much sun, and sparse rain. So for 30+ yrs why have my rosemary, thyme and oregano rebelled? Outside i had sandy soil but they struggled at best. Inside they are the thirstiest of my many plants. Even first yr plants have wilted if not watered every other day, and several died this fall when watered on 4th day after vacation. And in pots inside there is of course better soil, less sun and more water, so less stress. They should be the most drought tolerant - not the least, right?
Anne Arundel County Maryland
Yours is an interesting question.
All three of these should be sited in full sun in light, well-draining soil to do their best.
There are too many factors involved (including so many cultivars) to say why they haven't grown well for you outdoors, but would suggest you amend your soil with organic material additions like Leaf-Gro or compost, which is beneficial. We would also recommend having a soil test done if you haven't recently.
Here is a link to our soil testing page with all the information needed, including links to a list of regional soil labs that can complete the analysis for you: http://www.extension.umd.edu/hgic/soils/soil-testing
Rosemary can have a leaner, but still well-drained soil, and likes a pH in the 7 to 8 range.
Unfortunately our humid weather can cause diseases that these three plants wouldn't normally get in their native regions of arid weather.
Indoors, these plants need as much light as you can possibly give them. They shouldn't be incredibly thirsty though. It is possible to mistake wilting from over-watering and root rot with under-watering. Don't water just because the soil surface looks dry, but put your finger into the soil about a half and inch to check for moisture.
Because the winter light is so low, we wouldn't expect the plants to grow very much at all (and what does grow may look 'stretched') or have much need for water in the winter. They might survive, but not necessarily thrive.
Do not fertilize until spring.
So this will remain a mystery. As stated in orig question, plants wilt when not watered so not root rot (and there are drainage holes in pots), and leaves recover after watering. Further, i believe pH and nutrients affect growth but lack thereof should not cause wilt, no? Although all 3 are first yr plants which have been up-potted 3 times, in lieu of other info, my only alternative apparently is to up-pot again (despite crowded space makes that difficult).
1. Though established rosemary tolerates drought well, young plants need more water--as much as every 3-5 days: http://homeguides.sfgate.com/rosemary-wilting-90190.html.
2. Up-potting can result in a plant being in a pot that is actually too large for it, meaning it cannot use the water quickly enough and, thus, sits in wet soil too long
Resulting roots rots cause wilting, which appears to be lack of water, and leads to more watering. Thus a vicious cycle begins. Check the roots of your dead plants for rot, to be sure this isn't happening.
Thanks, but these (in pots) were healthy, albeit root-bound, plants in 3x3 pots in late spring, so don't think qualify for "young." I teased out the roots when repotted and they have been fine, except for thirst. Fertilizer has been ltd to a seriously diluted fish emulsion once a month. I know up-potting should be incremental, and that is what i have done and will continue. And all are in plastic not clay. I just counted my inside plants and have slightly over 100, so have plenty of comparisons (in spring with seedling cells and pots i exceed 300). I remain perplexed why these supposedly rugged plants are so problematic. Well, no one said this would be an easy hobby.