Pre-emergent weed control measures start now

Controlling certain weeds takes some strategic planning and mid-March the game begins. I personally don’t care about weeds in the lawn, but I do try to keep them out of the landscape beds and the vegetable garden.  
I also prefer to approach the whole affair with as little chemical input as possible so I have developed a well-timed strategy of hand-weeding, mulching, using corn gluten as a pre-emergent and a little flame throwing, I’ll explain.
As soil and air temperatures warm, weed seed begins to germinate.  
You have probably already noticed some cool season weeds like henbit, chickweed and wild onion. Perennial performers like violets, dandelions and creeping Charlie are not far behind.
Annual weeds spread by seed so if we address the young seedlings now, especially before they bloom, with a hoe or scratching tool in hand, we have eliminated one generation.  
If the weed is a perennial, like violets or wild onion, then a bit more effort may be required.  
Every spring when the ground is moist, I take my spade to the garden and pop out onions and violets from the mixed perennial beds. In a matter of about three years total I have eliminated some major weed problems by pulling, cultivating, mulching and using corn gluten pre-emergents.  
If you are battling tough weeds like creeping Charlie, you may be required to use a chemical to begin with; but if you properly use the product you should be able to follow up with hand weeding and cultural practices for long-term management.  
One treatment of a product that contains the active ingredients 2, 4-D, dicamba and trichlopyr is effective on the most difficult weeds.
I would like to emphasize, however, that you want to follow label instructions exactly.  It is better to use it once and take care of the problem then to be tempted to rely on synthetic herbicides throughout the season, every year.
Clearly there is no magic bullet for weed control, but we can take some common sense measures to devise an overall management plan. We have come to rely too heavily on the use of herbicides to fix our problems when we already have all the free tools we need: memory, reason and nimble fingers.
Once your weeds are under control, follow up with smart cultural practices like maintaining a taller stand of turf (don’t mow grass shorter than 2½ inches); use mulcing materials in beds (no more then 2 inches), and hoe or hand weed as soon as you notice something.  
You can also use corn-gluten-based products as a granular pre-emergent to prevent weed seed from germinating.  For this product to work effectively, you must follow up with an application about every 10 weeks.  
Corn gluten is perfectly safe and provides a small amount of nitrogen to the garden as well. Don’t use it where you are starting plants from seed, however.
We also employ a flame weeder that I will use on annual weeds like henbit that can carpet some areas in the vegetable garden in spring.  
The “Dragon” effectively cooks young tender weed seedlings but getting to them early is key.  
There are organic herbicides that prove effective for spot treating, too.  
Organic Gardening magazine recently rated the effectiveness of Perfectly Natural Weed’n Grass Killer. The active weed killing ingredients are clove and citrus oils so look for similar products accordingly.  
A full strength vinegar spray will wither a weed, too, but you need to come back to it several times to starve the roots (and you need a stronger vinegar solution than what you get at the grocery store).  
In many cases a spade is adequate for the handful of deep-rooted dandelions in the perennial garden, no need to go overboard with the chemicals.  
Dandelion leaves are a tasty addition to a salad, so you may consider harvesting the foliage before you toss the root; and purslane has become a favorite of mine in summer dishes.