Saturday, September 18, 2010

Happy Fall, Y’all

You may have noticed some gardeners have strong opinions about fall maintenance. The two camps are represented by those who believe the garden needs a good scrubbing, so to speak, before being put to bed; and those who believe nature has been my dogtaking care of itself for a long time and needs little assistance. I don’t really have a dog in this fight (as you can see, my dog is a lover, not a fighter), but I can offer suggestions that seem sensible.

First of all, if you have worked to create a garden full of lovely autumn vignettes, you don’t want the detritus of fall to detract from their beauty. Just as in high summer, you will want to continue to remove anything tatty from the composition. Weeds will stage a coup and take control of your garden over Seattle’s mild winter if not fended off. Weeding, deadheading and Echinacea and Origanum removal of spent foliage goes on. Remember that anything diseased should be destroyed. If you leave it in the garden, you will surely see it again next year. Everything else can go into the compost for next year’s mulch.

After the first hard frost, remove the leaves from the beds. Leaves left in the beds over winter and harbor insect pests, bacteria and fungi. Even large perennial leaves, like those of hosta, should also be removed to eliminate a favorite slug habitat. I use iron phosphate bait which I try to put out twice a year, in April and October. Large leaves, such as vine maple, can smother lawns and even small plants. If you are able to effectively shred your fallen leaves with a mower, you can leave them right where they are and their nutrients will benefit your lawn. I’ve never been able to do this, perhaps because it is so wet this time of year.

After frost, you will also cut back your perennials, but be judicious. Some of the seed heads, pods or sturdy stalks are architecturally interesting and can attract birds to your garden to entertain you and provide some late season pest control. OrnamDeschampsia and F. 'Tom Thumb'ental grasses provide interest and movement in the winter garden and, in any event, they are petulant if you cut them back before spring. Like some perennials, notably mums and fuchsias, they will overwinter more successfully if you leave at least 10” or so of this year’s growth. Snow will potentially collect around the crown and insulate the plant during the coldest days. Just last year’s stems alone appear to give these plants the bit of cover they need to return for another year.

Fall is when you divide spring blooming perennials and plant new ones, as well as spring blooming bulbs and transplanted trees, shrubs and perennials. Some passionate dahlia aficionados will dig and store their bulbs; I have tried this and never been successful. I was treating my dahlias as annuals until I got a tip from Cisco. Now, when  I cut my frost blackened dahlias to the ground, I cover them with fern fronds and then evergreen boughs. It seems that most of the problem with dahlias, fall pinkswhich are native to Mexico, is not the cold in our Zone 8-9 gardens, but the RAIN! Keep them mostly dry (some rain filters through both the fronds and the boughs) and some varieties will return for you year after year. Try this with any bulb that detests wet feet.

Many gardeners, especially in very cold areas, mulch in the fall to regulate the soil temperature and protect roots from frost-heave. I mulch in late winter for weed suppression and moisture retention. Remember that if you decide to use bark, you must add nitrogen to compensate. The decomposition of the bark uses all the available nitrogen in the soil. If you use compost, you are improving your soil every time you mulch.

Basically, my approach to fall maintenance is: if I like it, make it look good. If I don’t like it, rip it out. If a little work in the fall can eliminate a lot of work later, do it. Actually, that is my approach to a lot of things. Try it-you may like it.

2 comments:

  1. I love compost! Cisco is very smart. re: dahlias...I have tried the ferns/tree boughs in previous years, and it really helps for getting repeat bloomers. However, I still lose a few every year! I have also tried digging them out and storing them in wood chips - but that still didn't help me. Maybe i need a dehumidifier. ;) My favorite dahilia is called "Seattle". :)

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  2. Yes, I lose a few every year, too.

    I have had the best luck with the Gallery dahlias. 'Rembrandt', 'Art Fair' and a few others have come back reliably for up to five years. Also, the grand old variety D. 'Bishop of Llandaff' returns every year.

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