Summer Care of Herbs in Planters
Answered by: Inge Poot
Question from: Stephanie Taylor
Posted on: August 6, 1999

My neighbor is on vacation and she has left me in charge of all her plants. She has two square planter boxes of herbs (basil, rosemary, thyme, parsley etc.). My problem is that they are all croaking and she won’t be too happy with me if they are all dead when she gets back mid August. I have consulted books, cookbooks and the local paper’s Food Day section and no help. Now I have turned to you. Do you think I could be overwatering? That is what I suspect as they all say "Full Sun" on those little white tabby things.

The herbs you listed as being in the planters all like good drainage, but a slightly moist soil.

The planters could be hard to water if they do not have adequate drainage. They work best if they have unobstructed drainage holes on the bottom. To prevent the holes from plugging up it is a good idea to put a layer of gravel or other drainage material on the bottom of the pot, before adding soil. If the pot has no drainage hole, it is essential to have a layer of gravel or broken clay pot pieces that will create a reservoir at the bottom of the pot for air and excess water. It is not easy to water a pot with no drainage holes correctly. If you think you have overwatered such a pot, lay the pot on its side overnight, to allow the water to drain out. After this do not water again until the top 2 centimeters of soil are dry. Test this by sticking your finger into the soil. When you water add no more water than would be needed to 2 centimeters of water over the entire surface of the pot. You can estimate the amount required and add it via a watering can. With practice you will eventually be able to do it with a hose too.

If you have over or underwatered you will have killed a lot of roots. The plants therfore cannot supply enough water to the top of the plant with the limited roots left. Trimming the tops will help and shading the plants with newspaper to reduce water needs will give the roots a chance to regrow. Shading the pots might also be a good idea during a heat wave to prevent the roots from getting cooked. Once they are cooked, the plants will react just as if you had over or underwatered them.

Fertilizing is also important for rapidly growing plants with a confined root system. When the plants are growing rapidly, they should be fertilized once every two weeks or even once a week if they are quite root bound. Use an organic fertilizer for edible crops and to be on the safe side and not burn the roots, use half the recommended concentration. In other words if for example, the bottle says to use 1 tablespoon per gallon, use half a tablespoon.

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