Weed and feed is the most popular bag in the lawn aisle for a simple reason. It promises to kill the dandelions and green up the grass in one pass with a spreader, on one Saturday.
It does both jobs, sort of. In most west metro lawns it does neither one well, and understanding why explains a lot about how lawn programs get built.
Two products that want opposite things
Granular weed and feed is fertilizer pellets coated with a broadleaf herbicide, usually 2,4-D, dicamba, mecoprop, or some combination. The two halves need different conditions to work.
The herbicide has to be absorbed through the weed's leaves. That means the granule has to land on a leaf and stick there, which is why the bag tells you to apply when the lawn is wet with dew and then not to water or mow for a day or two. If it rains that afternoon, much of the weed control washes off before it is absorbed.
The fertilizer needs the opposite. It has to get off the leaves and into the soil, which means it wants water soon after it goes down. Fertilizer sitting on grass blades does nothing for the roots.
So every application is a compromise. Either the weed control gets a chance and the fertilizer waits, or the fertilizer gets watered in and the weed control washes off. Neither half gets ideal conditions.
It treats the whole lawn for weeds you may not have
A spreader puts herbicide on every square foot, including the large share of a typical lawn that has no broadleaf weeds in it. Meanwhile the timing is set by when the grass needs feeding, not by when the weeds are most vulnerable. Those calendars do not line up.
It also locks you out of seeding. Most weed and feed labels say to wait several weeks, often until after three or four mowings, before overseeding, and to keep it off new seedlings. If the lawn needs thin spots filled in, which in west metro clay usually means fall aeration and overseeding, the herbicide and the seed are working against each other.
And it does nothing for the grassy weeds. Crabgrass, quackgrass and creeping bentgrass are grasses, so a broadleaf herbicide passes right over them. Our post on broadleaf weeds vs. undesirable grasses explains why those need entirely separate products.
Why fall is when broadleaf weeds lose
Here is the part most people get backwards. Spring is when dandelions are most visible, so spring is when people reach for the bag. Fall is when the weed control works best.
From September into October, perennial weeds like dandelion, creeping charlie and clover are moving sugars down into their roots to get through winter. Systemic herbicide applied to the leaves rides along with those sugars into the root system. A spring application often burns the top off a dandelion, and the root sends up a new rosette a few weeks later. A fall application has a much better chance of killing the root.
The window closes as it gets cold. Weeds have to be actively growing for any of this to work, so daytime temperatures in the 50s and 60s are what you want. Once hard frosts start, typically by late October out here, the plants slow down and so does the herbicide. Our posts on dandelions and creeping charlie go deeper on each.
The Minnesota phosphorus rule
One more thing to check on any lawn fertilizer bag in Minnesota: the middle number. State law restricts phosphorus fertilizer on lawns, so most products sold here read something like 24-0-6. Phosphorus is allowed for establishing a new lawn or when a soil test shows a need for it. Phosphorus that runs off lawns feeds algae in lakes, which is why the rule exists, and the lakes around Maple Grove and Plymouth are exactly what it protects.
What to do instead
Separate the jobs and time each one on its own calendar.
- Feed the lawn when the grass needs it. In Minnesota that means a schedule spread from spring through fall, with fall feeding doing a lot of the work of building roots for next year.
- Control weeds when the weeds are vulnerable. That means early spring for crabgrass prevention, and broadleaf control while weeds are actively growing, with fall as the strongest window.
- Spot treat where you can. A lawn with a few dozen dandelions does not need herbicide on every square foot.
- Thicken the turf. Dense, well fed grass mowed at 3 to 3.5 inches shades out weed seedlings better than any product.
That is how our fertilization and weed control program is built. Fertilizer and weed control go down as separate steps, each timed to the Minnesota growing season, and the program controls undesirable grasses as well as broadleaf weeds. If weeds come back between visits, we come back and treat them at no charge.
Not sure which weeds you are dealing with? Our weed identification guide has photos of the common ones we see across the west metro.
Frequently asked questions
Does weed and feed actually work?
Partly. The fertilizer greens the lawn and the herbicide kills some broadleaf weeds, but the two need opposite watering conditions, so each half works below its potential. It also does nothing for grassy weeds like crabgrass or quackgrass.
When is the best time to apply broadleaf weed control in Minnesota?
Fall, while weeds are still actively growing. From September into mid October, perennial weeds move sugars to their roots and carry the herbicide with them. Daytime temperatures in the 50s and 60s are ideal, and results drop off once hard frosts set in.
Can I use weed and feed and overseed at the same time?
No. Most weed and feed labels require waiting several weeks, often until after three or four mowings, before seeding, and the herbicide can harm new seedlings. Plan seeding and weed control as separate steps.
Why does Minnesota lawn fertilizer have a zero in the middle?
Minnesota restricts phosphorus fertilizer on lawns to protect lakes and streams from algae growth. Phosphorus is allowed only for new lawn establishment or when a soil test shows a deficiency, so most lawn products sold here are phosphorus free.
How long does it take for dandelions to die after a fall treatment?
Usually one to three weeks. The leaves curl and twist first, then the plant browns as the herbicide works into the root. Cold weather slows the process, which is why early fall applications show results faster than late October ones.
Do you offer weed control in Maple Grove and Plymouth?
Yes. Our fertilization and weed control program serves Maple Grove, Plymouth, Rogers, Corcoran, Medina and the rest of the west metro, with free return visits if weeds come back between scheduled applications.