Tuesday, October 6, 2009

Fall Cleanup, more or less

"In these golden October days no work is more fascinating than this getting ready for spring. The sun is no longer a burning enemy, but a friend, illuminating all the open space, and warming the mellow soil."
Charles Dudley Warner, 1829-1900, My Summer in a Garden

It’s October and the trees are beginning to give up their leaves.

When it comes to fall clean-up, there seems to be two schools of thought. One says do it, the other says don’t. I mostly follow the don’t group with a bit from the do group, but I’ll try to explain both.

For purists, fall clean-up consists of removing all decaying plant debris including fallen or yellowing leaves, spent flower stems and seed heads, cutting down to the ground any perennials that will or are dying back, raking the ground of any debris…generally tidying up and making the garden look ‘neat’. In doing so you remove hiding places and shelter for slugs, snails and bugs that will over winter as well as disease pathogens that remain in leaf matter on the ground (ie: rose black spot), all of which will come back in spring to torment you for another year. That doesn’t sound too bad does it?

However, all that raking and trimming can also leave the ground bare to sprout a whole new crop of weed seeds that will germinate and grow during fall and winter when you least want to get out and pull them. If you leave the weeds for a more convenient time to tackle them you will have a mess of weeds already dropping more seeds by the time you do get out there. I’ve read seeds can lie dormant in the soil for over 7 years. A little disturbance of the dirt exposes them to the light and up they sprout. Weed control for me means pulling or hoeing the little blighters whenever I see one and in fall I cover the ground with a blanket of gathered tree leaves that drop from my 2 vine maples, 1 Mountain Ash, 3 Katsuras, 2 Japanese maples and 2 Winter Hazels (Corylopsis). I look forward to fall when I can begin raking and putting this blanket over my garden’s soil. Not only do I get great exercise raking the leaves that fall on the lawn (no lazy leaf blower for me), the leaf blanket over the garden looks nice, and the weed seeds that blow around can’t find the dirt. Some leaves will blow around a bit in winter winds, but they are easily swept back into the garden on those sunny winter days when you have cabin fever. Over the course of the winter and following spring the leaves will decompose into mulch returning nutrients to your soil and improving its tilth.
All of the trees mentioned above have small leaves, so no mowing over them to chop is needed. Any leaves you spread should be small in size. Easiest if you plant trees with small leaves to begin with, but if you only have big leaves it is best to chop them up somehow. Some people mow over a leaf pile with a lawn mower, while others will drop leaves into a garbage can and plunge into it with a trimmer or weed-whacker. Either way, if they are too big they will just mat and rot into a slick mess and not allow air and water to penetrate down to the soil.
The leaves you don’t want to leave in your garden are rose leaves and any other leaves that appear to be diseased. Rose leaves can harbor black spot spores only to perpetuate the problem the following year.

If you want to plant some trees to produce your own fall blanket, look into Katsura. Hopefully they’ll grow in your region. The new leaves in the spring are plum color, they turn a beautiful green for summer, small and round, pretty as breezes rustle them. In the fall they turn golden to orange and best of all the FRAGRANCE! As they dry on the tree and fall to the ground they fill the air with an aroma very much like baked brown sugar! I adore fragrance in the garden!

Getting back to fall clean up…or not.
Removing seed heads from your spent perennials can remove natural food for the birds. It is so much fun to watch the chickadees dine on the Echinacea, Liatris and Caryopteris seed heads that remain swaying in the breezes in January when snow covers the ground. That said, I am selective about which seed heads I allow to remain. If the plant is a prolific self seeder I do cut seed heads off before they can make a mess for me to have to weed in spring. But I wouldn’t mind if the Echinacea popped up in a few more places and the caryopteris has never been a problem either, the birds seem to get every last morsel. Many hybrid plants may produce seed but it is often sterile, it’ll never sprout so there’s no problem leaving them on for the birds.
Some seeds are so decorative. Look at this fluffy seed of Clematis. A shame to cut it off, and I’ve never had them create a weedy problem.

Leaving the twiggy structure of the plant or shrub also provides some protection from freezing. As snow falls in and around the ‘skeleton’ of your plant, it creates a teepee of snow that insulates the trunk and root zone from freezing temperatures.
I do prune the tall stems down on roses but only about half way, leaving a strong, firm structure but reducing potential damage by tall stems being whipped and torn by winter winds or broken by heavy snow. Breakage like that opens stems to rot, decay or bug harboring. Further pruning is better done in spring, just before new growth comes on.
I also leave an inch or so of stems from bulbs help to identify where they are so I don’t accidentally spear them next spring when digging. Some claim this brings rain water and bugs down to the bulb causing rot or decay, but if that is the case I haven’t noticed any problems.

To me, fall cleanup is spreading compost from my own pile (I never have enough), spreading raked leaves, cutting down corn stalks, tomato and green bean vines, tenting the young winter lettuce so it will over-winter to feed us in February or March, minimal perennial trimming and generally enjoying the changing season with the earthy aromas only fall can bring. The majority of my trimming comes in spring when the new growth quickly covers that which I cut away.

Oh...do I have a problem with snails and slugs under that leaf blanket? Definitely yes, but then I live in the rainy Pacific Northwest where they are a problem anyway. I think the benefit outweighs the cost.

In bloom in my garden today: kirengeshoma palmata, ajuga, cyclamen hederifolium, colchicum, cicimifuga, hosta lancifolia, caryopteris, Echinacea, salvia, daphne, roses, coreopsis, hardy geranium, nepeta, solanum crispum, gauara, fushia, canna, schizostylis, green beans, borage, alpine strawberries, bulb fennel.

Photos by the author
Clematis photo courtesy of Pat Chissus


Shari B. said...

Hi Joan,

GREAT post! As always, I am AMAZED at your wealth of knowledge and experience with plants.

I am so happy to hear that it's actually a good thing to leave leaves down in certain instances. We have a lot of areas in our yard that are stone or wood chips where trees and shrubbery are planted -- I would never have guessed that if I rake the leaves off it could move the soil and allow sunlight down to dormant weeds seeds. I definitely do NOT want weeds to pop up in those areas. Plus I actually like the look of the fallen leaves (my HOA may not, but I'll keep them as is unless asked to do otherwise!)

Thanks for the great info! I always learn so much from your posts!

Can't wait for the next one!

Joan said...

Hi Shari,
Thanks for the encouragement. Regarding mulch, your stones and wood chips are also considered mulch as they cover the soil. Definately weed seeds can and do find their way through both of these but not as easily as if the soil was bare. I don't have either of these in my garden to cover the soil so I use the leaves. You may not need the leaves in your case. But try it this year and see if you like it or not. If you have any bare soil garden areas you may just want to move them there.