Whether you purchase your herb plants from the nursery, or start your herbs from seed indoors, you will need to harden them off (get them acclimatized to being outside).
Why Harden Off Your Herb Plants
Herb plants grown indoors live in a sheltered environment. These plants need to get accustomed to the outdoor elements, especially strong light from the sun, and the wind.
Herb plants purchased from a nursery have usually been raised indoors in a greenhouse and also need to get acclimatized to the outdoors.
What Happens If You Don’t Harden Off Your Herb Plants
If you don’t harden off your indoor and greenhouse grown herb plants before permanently moving them outside, the plants stand a much smaller chance of surviving once they are outdoors.
- Tender herb plants are likely to be destroyed by the elements:
- Herb leaves get burned by the sun
- Herb plants can’t withstand the wind, with the weak stems breaking
- A strong rainstorm knocks down the herb plants
- Young herb plants wilt beyond recovery
The over-stressed herb plants that do survive usually remain weak and less productive than they otherwise would have been.
If you placed your herb plants outside in a constantly shaded spot that was sheltered from the wind, and from downpours, your tender herb plants might be OK. Certainly your losses will be much smaller than leaving the plants out in the open.
How To Harden Off Herb Plants
The standard method of hardening off any herbs that were raised indoors, is to take the plants outside for a brief period of time the first day, and leave them out progressively longer each day.
A general guideline is to start with two hours in a protected shady spot, and extend the time the herb plants are out by two hours each day, gradually increasing sun exposure. After 5 or 6 days, you can leave the herb plants out overnight.
Ideally, start hardening off your herbs on a calm, cloudy day. Of course, the weather rarely cooperates.
Place plants in a shady sheltered area – use barriers to create shade and shelter if you do not have a suitable outdoor area.
The garage is also a good place to use for hardening off herb plants initially. Ideal if it’s very windy outside. Place your plants in the garage with the garage door open, and leave them in there while you are out and about doing your yard work.
When To Bring Your Herb Plants In:
- Your herb plants are drooping or look like they’re struggling
- The weather is not cooperating – especially strong sun, high winds, and storms
- The temperature is expected to drop significantly at night,
- There is danger of frost
5 Tips For The Time Challanged
Problem is, most of us work all day. So what to do?
1. Some time is better than no time. Any time spent hardening off your herb plants before leaving them out permanently increases your herb plants’ chances of surviving and thriving.
2. Begin after work. Take your herb plants outside for a couple of hours when you come home from work. This is actually a good time to start hardening off herb plants as the sun is less strong, and the wind tends to die down in the evenings.
3. Cut yourself some slack. If you get home from work too late, just skip the day and continue hardening off your plants the next day. It’s not worth stressing about it, and your herb plants will be fine.
4. Use the weekend to your advantage. Start hardening off your herb plants after work on weekdays. Then leave them out for longer periods of time over the weekend. They should be ready to leave out all day in a sheltered area, come Monday.
5. Protect, protect, protect. Once you are leaving your herb plants out for the entire day, make sure you protect them well with barriers to shelter them from the elements. Because you won’t be home should the weather turn, make sure they are protected even if the forecast calls for a mild overcast day.
Hardening Off Overwintered Tender Perennial Herbs
If you brought your tender perennial herbs indoors for the winter, they too need to be hardened off before you leave them outside for the summer.
All winter, your herbs have been exposed to lower light conditions, and no wind. The growth on the herb plants is usually noticeably weaker.
Problem is, these are mature plants, sometimes even small trees (e.g. bay laurel), which makes them heavy to lug in and out of the house each day.
If you can, use a trolley or a wagon. You could even wheel your herbs in and out daily without removing them from the wagon.
These mature herb plants usually require less time to harden off than young herb seedlings. Still, don’t rush the process. Gage the hardening off time by how your tender perennial herbs are responding to being in the outdoors.
Final Note
At the end of the day, whether you are hardening off young herb plants or mature herb plants, let the plants be your guide. If they are looking droopy or you notice the leaves are starting to burn, move them into a more protected shady area or bring them indoors. If your herb plants are standing strong, you can leave them out a little longer.
Happy growing,
Herb Garden Gal
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