Question
QUESTION:
our flower garden was mulched last year with hard wood. Now my impatients will not grow in the garden.  Other plants are doing fine.  This is the second time this has happened to me.  What is the problem and how can I correct it.


Thank you.

ANSWER: I'm reluctant to answer your question because of your nebulous description of the problem - your impatiens 'will not grow', on top of which 'this is the 2nd time'.

But I'm more worried you would be too frustrated to write again.  So I'm going to do my best to give you some information that might help you add up your variables and figure out what to do about it.

Wood mulch can be a terrific way to minimize weed invasion and retain moisture.  But there are cons.  For this reason, many people (myself included) place layers of newspaper at the bottom to block certain natural chemicals produced by the wood(s) from reaching the soil.

You may have heard of the problems with growing anything near a Black Walnut tree.  Black Walnuts and their relatives secrete toxic ompounds from their leaves, bark and roots, into the soil.  It keeps out the competition.

Sawdust or chips from Redwoods and Cedars, certain Fir trees, even Eucalyptus Trees can taint soil for years.  Here in the Northeast, the needles and stems of numerous firs may release chemicals that sicken plants growing nearby.  When it rains, and especially if it rains a lot, as we have seen this Summer, the chemicals reach more roots and can do a lot of damage.

In warmer years, it is possible that heat can build up under these dark blankets to the point where you give your bedding plants heat stroke.  But that would not be the case when the temps are in the 70s and low 80s, and the plants are grown in the shade, as Impatiens usually are.

Synthetic mulches now on the market -- what's up with that? -- can do a real number on a garden.  People are finding their plants succumbing to toxic levels of Zinc and other minerals and various toxic residues present in these materials.

But you are growing au natural with your hardwood.  You are at least on the right track.  And there is still time to correct any problems.

First, please tell me what brand and/or type of wood this is.  It should identify it on the bag.

Next, would you tell me what symptoms your plants are showing?  Are they dieing?  What happens before they die?

What kind of watering schedule are you on?  Mulched plants need very little attention to watering.  Even moisture-loving Impatiens can succumb to root rot and anaerobic soil.  Remove one of the plants and tell me what the root system looks like.

What else have you grown in the same site?

Finally, what else, if anything, are you doing to help your Impatiens grow?  (In my book, the less you do, probably the better, including fertilizing.)

rsvp and thank you for writing,

THE LONG ISLAND GARDENER


---------- FOLLOW-UP ----------

QUESTION: This garden is under Walnut trees and we have learned all about the toxic soil situation and have been fighting it for years, but my impatiens have always done well until two years ago when the landscapers mulched the garden with hardwood mulch without permission.  so last year another landscaper replaced the soil& replanted bushes that can grow under  Walnut trees.  I was very excited until he insisted on mulching the garden telling me that it was good for the bushes etc.  I knew it might be a mistake, but what do I know.
So...we planted our impatiens this spring after scrapping away most of the mulch and spreading bagged soil with miracle grow in it where my plants were planted.  They were doing great for about three or four  days then they looked wilted. The leaves curled and the flowers fell off or were very small and underdeveloped.  We water the same as we have always done and the plants keep looking worse.   I planted begonias that seem to be doing better and another shade plant that looks similiar to inpatiens (can't think of the name at the moment) and it is fine too.  I used the same soil with miracle grow in my pots and all the plants are doing well including the impatiens.   I have looked at the roots and they are in good condition.  White and not rotted.

Some of my perennials are doing fine, others not as well.  My chicks n hens look wilted too.

Thanks for your help.   

One other thing I want to mention.  For years we have used "Liquid fence" which is a spray that keeps rabbits and deer out of the garden.  I don't know if this caused a problem or not. I called the company and they said that they have not changed their product in any way and that since the smell isn't as bad when we applied it and that the plants are still being eaten - it was probably old product.  She is sending me a new bottle.

I'm afraid to use anything on my plants at this point.

Very disappointed in my garden that I thought would be "beautiful" this year.          

So, if the hardwood mulch has ruined my soil, what can I use to correct the problem?

Answer
Interesting problem. Thanks for the additional information.

For the record, Impatiens as a genus are generally not as susceptible to the chemicals in Walnuts -- Juglones, as you may have heard -- as other plants.  They would grow better without the chemicals, but it won't kill them.

I do think however that it is clear from your description that you are absolutely right, the hardwood mulch is to blame.

The problem here is that you don't have any idea what this mulch is.  Hardwood, perhaps.  If so, which one?  And now that it's down, what can you do about it?

The Begonias are also not thriving thanks to the 'Hardwood Mulch' your landscaper provided.  Some woods as I mentioned earlier are fine.  But there is clearly nothing fine about this mulch.

So I have a suggestion.

1.  Put your Impatiens in pots and have them recover.  I strongly recommend against Miracle Gro Soil.  This is a built in fertilizer that is expensive and resistant to The Real Thing, i.e., rich organic matter teaming with beneficial microbes.  Those microbes fight disease and generate minerals and vitamins.  Miracle Gro and soil that has it pre-mixed into it is second rate.

You would be better off taking soil right out of your garden, adding Humus or aged Manure out of a bag, some sand, and then potting up your Impatiens in this nice, new growing medium.  Soil from your garden, which should be Juglones-free (get it from the other side of the house, far from the suspicious tree), would be perfect.  It will have microbes and spores from microbes that will serve as a culture for everything you add, and these will convert the Soil into nutrients and feed them to your impatiens with no ill side effects.

2.  Once your Impatiens have recovered, plunge the pot and plants back into the same spots under the tree and cover with the wood mulch.  See what happens.  Perhaps they will thrive if protected from direct contact with the wood.

Try to find out where this landscaper got his wood from.  That could answer a lot of questions.

Given your experience, don't let him do that again.  He meant well, but life is filled with surprises.

Please let me know how your plants turn out, esp after you resume their life under your Walnut Tree.  I'd like to see this work for you.

L.I.G.