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Checklist for cool-season lawns and how to avoid common, outdoor fall mistakes

Friday - 9/6/2013, 11:52am  ET

September is one of the best times to finish outdoor lawn chores before the winter. (Getty Images)

Put away your pruning sheers

WTOP Garden Editor Mike McGrath.


This is a very important time of year to accomplish certain outdoor chores and an even more important time to avoid many common outdoor mistakes.

  • Do finish any sowing of cool-season grass seed by the end of the month.
  • Do aerate cool season lawns if your soil is heavily compacted clay and/or drains poorly.
  • Do give cool-season lawns a big natural feeding.
  • Do not do any of the above lawn chores now if you have a warm season grass, such as zoysia or Bermuda. They are installed and aerated in the spring and fed in summer.
  • Do apply milky spore to your lawn (any kind of lawn) if you find grubs underneath dead brown areas. (Lift up a patch or two to check. No grubs? No need to spore.)
  • Do sow seeds of lettuce, spinach and other cool-weather greens.
  • Do pull any new flowers off your tomatoes, peppers and other summer crops that need time to ripen. There isn't enough growing season time for those flowers to form viable fruit, and removing them will move your existing fruits along.
  • Do plant individual cloves of garlic for harvest next July.
  • Do not prune anything now. Trees and shrubs are beginning to go dormant, and pruning will cause new growth and weaken the plant.
  • Do not plant spring bulbs yet. Wait until after Halloween.

Best time to move a tree

Betsy in Falls Church writes: "Is it too late in the season to transplant a crape myrtle tree?"

Not at all, Betsy. In fact, it's not quite late enough yet. The worst time to try and move established plants around is in the heat of summer. The survival rate is dismal.

The best time is when they're fully dormant in the winter.

Second best depending somewhat on the plant is in the fall as the plant is going dormant for the winter or the spring, just as the plant is breaking dormancy.

Crepe myrtles benefit from a springtime pruning, which makes early spring ideal for your specific plant. Wait until new growth appears next season, cut the plant back a bit (good for the plant and it will reduce the weight) and then move it to its new location.

Be sure to have a lot of help on hand. You'll need to unearth a huge and heavy root ball to make the move a success. Using shovels, dig up a big island of soil, trying to impact as few roots as possible. Then place this giant heavy thing on a tarp and carry it to the new location. Install it in unimproved soil at the same height it was or higher, mulch with an inch of compost and water deeply and slowly for several hours right away. Then water it again every second or third day until there's good rain.

New lawns are easy, it's comedy that's hard...

Lucy in Gaithersburg writes: "I really want to install a new front lawn (currently a tiny 19-by-7-foot weed patch) mid to late September. I want to rip up all the weeds, till the soil, add top soil and then sow grass seed. Do I till in corn gluten meal before topping with soil? Should I till in milky spore powder or lime or anything else?"

No, Lucy. If you have any grubs, the tilling will kill them, so there's no need for natural grub-killing milky spore. You never add lime without a soil test. And corn gluten would prevent the grass seeds from germinating.

Weed removal, tilling and adding an inch of top soil (or even better, compost) is pretty much all you need to do. Just make sure you level the prepared surface really well, soak that level surface thoroughly before seeding, sow the seed on top of the wet soil, cover with a little bit more top soil or compost and then mist gently every morning until the new grass is up and growing.

Or, consider having sod installed. Sod is a very affordable alternative for small spaces like yours.

Corn gluten beats crabgrass anywhere

Barb in Gaithersburg writes: "I have crabgrass in my flower beds, which I am planning to rip out, but I expect the crabgrass has already dropped seeds that will still germinate. Can I use corn gluten meal in the flower beds without harming anything? Will it work on other types of weeds? And when is the best time to put it down? In fall?"

No, Barb, crabgrass seed germinates in the spring, so you would apply the corn gluten to your beds at the same time lawn owners would to their turf. That time is next spring, just as soil temps reach 55 degrees - as measured 4 inches down - and redbuds and forsythia begin to bloom.

Corn gluten won't harm your existing plants (in fact, it will feed them, so don't use any other fertilizer), but you won't be able to directly sow any flower seeds for six weeks after application. Finally, corn gluten will stop any weed seeds from germinating, but will not affect any existing weed plants.

A mutant hybrid flying lobster hummingbird thingy

Walter in Annandale recently saw one of my favorite natural wonders up close. He writes:

A reader spotted this hummingbird-like moth in his garden. (Courtesy Photo)

"While deadheading the spent flowers from a butterfly bush, I was startled by a creature that I first thought was a small hummingbird, but on closer observation appeared to be something of a flying lobster! It was fuzzy and pale green in front with a dark rusty red rear. It had eyes, antenna and a tail resembling a lobster, yet it moved and hovered like a hummingbird (just a bit slower.) My 14-year-old daughter is convinced it was some kind of mutant hybrid. Any idea what it was?"

Walt, your description of the amazing hummingbird moth was exceptional as were the photos you sent. Great work on your part!

This wildly colorful moth flies during the day, hovers furiously and feeds on pollen and nectar just like its namesake but it was once a caterpillar, not a baby bird (or crustacean or pet of the X-Men). Here's a nice article that lists the plants that attract this all-too-infrequent, fascinating garden visitor.

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