One of the things about writing a column for 40 years is that things change and advice has to be corrected. A bunch of questions this week demonstrate this. We learn more and more about plants every week and thus need to adjust how we care for them.
For example, the other day I was stopped by a reader who wanted to know if I cleaned up my perennials and annuals in the fall. The answer is I don't clean up at all. Hopefully the answer to this question did not come too late for you.
Admittedly, 20 years ago I would have urged all readers to clean up the yard. Back then it was simply the rule that perennials had to be cut back in the fall and the debris from the work had to be removed from the garden. This was particularly true of peony leaves and stalks as everyone insisted plants would end up the following season infected by virus, fungi and bad bacteria if this year's growth wasn't removed. To make matters worse, some experts even insisted that the stuff not go into the compost pile lest some of the bad organisms survive the composting process.
The fact of the matter is that removing the above-ground parts of perennials is actually more of problem in the long run than leaving them when it comes to diseases. All manner of beneficials, from insects to bacteria and fungi, reside on spent stalks, stems and leaves. This soil food web organism diversity is one of the factors that allows plants to maintain their health. Remove these from the garden in the fall and they take a much longer time to repopulate in the spring, often too late as the bad guys are very opportunistic and move in first.
One big worry is that by not removing stalks, rot will occur in the crowns of perennials because water will collect in the "cups" left at the ground end of the stalks. The fact of the matter is that cutting the stalks is exactly what leaves a small cup at the base of the plant in the first instance. Just leave things alone until spring. That is what Mother Nature does. It works.
Furthermore, I have never seen rot happen when gardens are properly mulched. Mulching, in fact, is the only thing you really need to do to your perennial beds. Twenty years ago we didn't advise mulching. Today, however, it is a must. And a bit of compost in the fall before mulching isn't a bad practice either. Birch leaves are free for the taking and make great mulch. If you want to run them over with a mower first, that is fine and will speed up decay, adding lots of goodies to your soil over the winter.
Next, the same advice goes for pruning trees this time of year. We used to say it didn't matter. Today, I say don't do it unless you are dealing with a dangerous situation -- if, for example, by not cutting or trimming you risk someone, or someone's vehicle, getting hurt. The reason is simple: The tree is shutting down and shunting nutrients into the root system for winter storage and spring use. It isn't going to be able to properly protect any cuts you make because there isn't any photosynthesis. Wait until just before spring to prune.
Next, can you use outdoor garden soil to repot indoor plants? Sure, if you have good outdoor soil. By good, I am particularly referring to structure. The soil has to be full of organics and drain well. It should smell good, too, indicating good aeration.
Again, it used to be that folks insisted all potting soils be sterilized. In fact, my father, like many avid gardeners, had a special box that would steam and sterilize garden soil for use indoors. I even advised using a microwave with damp soil in years past.
Of course, we know now that sterilization kills members of the soil food web that not only create structure but also produce vitamins and hormones that protect plants. So, if your yard's soil drains well and has good nutrient value (demonstrated by testing, which you can do this time of year), go ahead and use it for indoor gardening.
Jeffs Alaska Garden Calendar
Tool care: Learn how to properly clean, maintain and sharpen your hand tools before you put them away for the winter. 6-8 p.m. Wednesday, Oct. 14 at the Alaska Botanical Garden. Go to http://alaskabg.org/abg-workshop-tools-of-the-trade to learn more and reserve a place.
Worms and Wine with Will at the ABG: Worm castings can be used as part of a potting soil mix or as an addition to the soil in your garden and are easy to get if you have worms. Class and drink on Oct. 17. Go to http://alaskabg.org/abg-workshop-worms-wine-with-will to learn more and reserve a space.
House plants: Pay some attention to yours now. Repot if necessary. Give them some artificial light.
Jeff Lowenfels is co-author of "Teaming With Microbes" and author of "Teaming With Nutrients." Contact him on his website at teamingwithmicrobes.com.