#1: Reseed and/or plant new lawns in the North.
Our Inbox is overflowing with lawn care requests that are more hopeful than a five-year old's letter to Santa asking for his very own T. Rex to take care of that nasty Tommy down the block. Sorry, kids—but there is no substance, chemical or organic, that will magically erase every weed in your lawn so that you can then just reseed the resulting bare spots. And let's be honest; by the tone of most of your emails, getting rid of every weed would probably result in one huge bare spot that you used to call a lawn.
But those of you asking such questions right now have got one thing right—this is the perfect time to reseed or sow a brand new cool-season lawn in the North.
Cool-season grass keepers who have a decent-looking lawn with just a few bare spots showing should begin the reseeding process by having a load of high quality screened compost or aged mushroom soil delivered. Fill wheel barrows with the compost, dump it out bit by bit around the lawn, then go back and rake it in nice and even. Then sow the seed that you hope will match your existing grass in the bare spots, cover those areas with a ¼ inch more compost and keep it all watered till the grass is up. The results should be spectacular, and you will have also provided the perfect fall feeding for your lawn.
But if your cool-season lawn is a ratty mess, seize the opportunity to start over. A cool-season lawn sown in Spring will always struggle, while one sown in the Fall is virtually guaranteed to thrive; just ask anybody other than a lawn care rep looking for work in the Spring. You have two choices to get rid of the old greenery. One is to rent a sod cutter to simply remove the mongrel mess you've been calling a lawn (compost the remains in a big pile; it will become perfect fertilizer for the future). The other is to rent a tiller or tractor and tear up what you have; continually raking away all of the green stuff that keeps coming to the surface until you have most of those weeds out.
Either way, follow up with a LOT of organic matter.
One of the biggest problems with American lawns is that virtually all were sown directly on un-improved clay or sandy soil (often because the builder removed the Kleenex-thick layer of somewhat less nasty dirt that was there so his Brother-in-Law could sell it back to you as 'topsoil'). Starting with a bed of rich organic matter instead of a surface that more resembles sheet metal or a sieve greatly minimizes future problems. So till as much compost or aged mushroom soil as you can into your nasty dirt, sow the seed, rake it in, dust a thin layer of compost on top, keep it watered and weeds will hate you.
And if your cool-season lawn needs no work, give it a big fall feeding with compost or corn gluten meal. Just remember that you cannot use corn gluten meal and seed together; the pre-emergent properties of the CGM would prevent most of the seed from sprouting. That's why we always tell you Northerners to definitely use it in the Spring, when you shouldn't be sowing any seed, and when the CGM can prevent most of the dormant crabgrass seeds in your lawn from growing up big and strong.
(See our big Archives section of previous Questions of the week for LOTS more info on corn gluten and lawn care.)
#2: Get pansies in the ground!
Pansies wither in the heat of July and August, but thrive in cooler weather. That means that conditions are now right for most of us to put those pretty posies in the ground. Here in PA, my September planted pansies typically produce new blooms through Christmas. If the weather turns super frigid (or they get a nice white blanket of snow), they'll go to sleep and resume blooming early in the Spring. In slightly warmer climes (or less frigid winters) they can bloom from September straight through the end of June. That's ten months of beautiful, edible flowers whose high rutin content helps conceal varicose and spider vein damage. (To avoid the possibility of consuming pesticides, cut off any existing blooms when you plant, and only eat newly emerged flowers.)
#3: Get ready to put garlic in the ground
Garlic is fun and rewarding to grow. It's also so easy you can delude other people into thinking you have talent at this game. Get a hold of some dedicated planting garlic (available from many mail order sources) or buy some organic bulbs at the market. Carefully break the bulbs open into their individual cloves and plant those cloves at least six inches apart in your loosest, richest soil; about four inches deep in warm climes and six inches further North. Dig it all up next year after the bottom leaves turn brown (typically late June) and you'll get a big head full of cloves for every clove you planted.
#4: Don't plant spring bulbs yet
Go ahead and buy your bulbs, but don't plant them anytime soon or they could sprout prematurely. Keep the bulbs in a cool, airy spot until after Halloween and then put them in the ground. Clean up all the little pieces of wrapper afterwards and spray the bed with deer repellant to confuse squirrels and other criminals. Or just plant big, bright daffodils; no mammal doth molest them.
(For LOTS more Spring bulb planting and protection tips, see this previous Question of the Week.)
#5: Yellow jackets are NOT harmless native bees.
Every Spring, when I beg people not to kill ground nesting bees because they are harmless gentle natives whose pollination is essential to garden success, I try and add the warning that ground nesting creatures that look like honeybees in the late summer or Fall are vicious yellow jackets who are not gentle, want very much to sting you, and would steal your car keys if they could figure out how to steer. See this Previous Question of the Week for tips on how to safely destroy yellow jacket nests.
#6: Prune NOTHING—you hear me? Nothing!
Pruning stimulates growth. Plants are trying to go dormant right now. Pruning in the Fall is like someone slapping you awake after you've already been up 48 hours straight; it is not likely to improve your health. So men: Go watch football. Ladies: Hide the pruners from Helpful Men. As our esteemed horticultural consultant Frankenstein's Monster likes to put it: "Winter pruning; GOOD! Spring pruning; GOOD! Fall pruning; BAD!"