Understanding when and how to fertilize your lawn can help you and your grass stand out from the rest. This is a big question in early spring: “My lawn needs everything what should I do first, put down seed or kill my weeds? The reason why this question is tricky is because many of the weed controls will harm new grass seedlings. Here are your best two options: Do you have less than 75%… Overseed your lawn in the fall after killing weeds in late summer. If you’re late, scalp the weedy lawn, rake away all the debris, and spread grass seed. Some weeds will germinate and grow with the grass, but you can control them using a post-emergent herbicide before they spread further.
When and How to Fertilize Your Lawn
In some ways, lawns are a lot like people. Operating at the peak of beauty and performance requires a good diet and proper care. Lush, thick, green lawns depend on properly timed, properly balanced nutrition to look and grow their best. Understanding when and how to fertilize your lawn can help you and your grass stand out from the rest.
Starter fertilizers help your new seed or sod get started right.
When and How to Fertilize New Grass
If you’re starting a new lawn from seed, sod or plugs — or you’re doing bare lawn spot repair — a starter fertilizer helps grass get the perfect start. Unlike established lawns, new grass benefits from extra phosphorus, an essential plant nutrient that supports strong, deep roots. Some states only allow phosphorus-containing lawn fertilizers on new grass, so check with your county extension office if you’re unsure.
On fertilizer products, phosphorus is the middle number in the N-P-K ratio — usually “0” in normal lawn fertilizers. But with Pennington UltraGreen Starter Fertilizer 22-23-4, you get an ideal ratio of nitrogen, phosphorus and potassium, plus other essential lawn nutrients, including iron for deep green color. This premium fertilizer blend starts feeding new grass immediately and keeps feeding it for up to three months.
Always follow guidelines for the best time to plant grass seed for your region and grass type, then fertilize accordingly. For seed or plugs, apply fertilizer with a regular lawn spreader before you plant. If you’re starting a lawn with sod, fertilize after your sod is in place.
With any new lawn area, avoid using crabgrass preventer fertilizers or weed & feed fertilizers within four weeks before planting time. After seeding, wait until your new grass gets established and you’ve mowed your lawn at least three times.
Weed & feed fertilizers kill tough weeds and feed your lawn.
When and How to Fertilize Established Lawns
To keep your existing lawn looking its best year-round, choose a fertilizer plan that meets its changing seasonal needs. At Pennington, we make it simple for northern and southern lawns. Just follow our four-part annual lawn fertilizer program:
Part 1 – Early Spring
Between February and April, temperatures warm and weed seeds start to germinate. Prevent new weeds — and feed your lawn in the process — with Pennington UltraGreen Crabgrass Preventer Plus Fertilizer III 30-0-4. You can stop new weeds before their roots get established and control new weeds for up to five months.
Timing is critical for this step. Make sure it’s applied before crabgrass seed germinates — that happens when soil temperatures reach 55 degrees Fahrenheit. For best results, apply with a spreader to actively growing turf and give your lawn at least .5 inch of water from rainfall or irrigation within 14 days.
On top of weed control, Pennington UltraGreen Crabgrass Preventer Plus Fertilizer III 30-0-4 delivers iron and fast-acting nitrogen for immediate greening, and slow-release nitrogen for extended feeding for up to three months. Always follow the label instructions for your specific grass type. Do not apply this product within 60 days of overseeding. Wait until the following year before treating new sod.
Part 2 – Late Spring
Between April and June, existing weeds launch into active growth. Weed & feed fertilizers combine broadleaf weed killers with nutrients to feed your actively growing lawn:
treats northern and southern grasses to kill more than 250 weeds from tip to root. It feeds your lawn essential nutrients for thick growth and rich color. Plus, it keeps feeding for up to three months. , designed especially for southern lawns, kills tough existing weeds* and keeps controlling new weeds for up to three months. And while it does that, this product keeps feeding your lawn the essential nutrients it needs.
Always check weed & feed labels for your specific grass type and follow instructions carefully. Weed & feeds are most effective when weeds are young and small. For best results, apply the product in the early morning when grass is wet with dew and no rain is forecast for one to two days.
If you plan to overseed, avoid weed & feed for four weeks before. After overseeding, wait until your third mowing occurs. For sodding, sprigging or plugging, wait four weeks before you weed & feed so new grass can start without delay.
Part 3 – Summer
Between June and August, proper feeding helps strengthen lawns against heat and drought. Keep your lawn beautiful and resilient with Pennington UltraGreen Lawn Fertilizer 30-0-4. This premium lawn fertilizer, ideal for northern or southern lawns, keeps feeding for up to three months. Your lawn gets essential nutrients, including iron for rich color, and you get thick, lush green grass.
Always check the label for your specific grass type, then follow instructions accordingly. Used as directed, you can apply Pennington UltraGreen Lawn Fertilizer 30-0-4 to wet or dry lawns and not worry about fertilizer burn.
Part 4 – Late Summer to Late Fall
Between August and November, grass slows down and prepares for the winter months. At the same time, broadleaf weeds start active growth again. With Pennington UltraGreen Winterizer Plus Weed & Feed Fertilizer 22-0-14, you can feed your northern or southern lawn nutrients essential to its winter prep and spring green-up — and kill broadleaf weeds. As a general rule, allow six to eight weeks between fertilizing and your first expected frost.
As with all fertilizer products, check the label and follow instructions for your specific grass type. If you’re overseeding, wait until next year for weed & feed. Instead, turn to Pennington UltraGreen Lawn Fertilizer 30-0-4 for the year’s final feeding.
Always sweep excess fertilizer off sidewalks and patios to avoid runoff.
How to Apply Lawn Fertilizer for Best Results
Whenever you apply fertilizer, always follow best practices for fertilizer safety. For best results, mow your lawn one to two days beforehand. Then set your spreader to the setting recommended on the product label.
- For drop spreaders, start with two strips across your lawn’s ends. Then work back and forth, overlapping each swath slightly.
- For broadcast spreaders, start on the outside and work in, overlapping slightly as you go.
Always shut the hopper when you stop and turn to prevent a fertilizer pile. When finished, sweep excess fertilizer off hard surfaces, such as sidewalks and driveways, to avoid iron stains and fertilizer runoff.
By following these lawn fertilizer tips, you can keep your grass at the peak of performance, beauty and health. At Pennington, we take pride in providing you with the best in lawn fertilizers and expert advice to help you have a lawn you’re proud to own. Stay connected with our email newsletter for accurate, timely tips and offers to help you make the most of your lawn and home.
*dollarweed, clover, henbit and chickweed
Always read product labels thoroughly and follow instructions, including specific guidance for your grass type.
Pennington is a registered trademark of Pennington Seed, Inc.
UltraGreen is a registered trademark of Central Garden & Pet Company.
What’s First: Feed, Weed or Seed?
This is a big question in early spring: “My lawn needs everything what should I do first, put down seed or kill my weeds? The reason why this question is tricky is because many of the weed controls will harm new grass seedlings.
Weed, Feed or Seed?
Here are your best two options:
Do you have less than 75% good grass with bare spots larger than a few inches in diameter?
Answer: If lots of larger spots, then seed this spring. Be sure to use a special Starter Lawn Food plus Weed Preventer that is compatible with grass seed (the regular crabgrass preventers will keep grass seed from growing). If you do not prevent weeds when you seed, you are likely to be very disappointed as crabgrass and other weeds will germinate and choke out your good grass before it has a chance to take hold. A machine called a slit-seeder will help make sure the grass seed comes in contact with the soil. You just select the Turf Builder Grass Seed blend that is right for your conditions, such as sun, shade, heat-tolerant, etc. If you only have a few bare spots to take care of, consider Scotts EZ Seed. I think this is the best bare spot repair product we have ever sold! Spread the Starter Lawn Food plus Weed Preventer after you put down the seed. Feed your lawn again in one month after seeding with Turf Builder Lawn Food. Once your new grass has been mowed 4 times, you can kill weeds with Ortho Weed B Gon MAX plus Crabgrass Killer OR Roundup For Lawns.
Do you have more than 75% good grass however your lawn is thin and weedy without widespread bare spots?
Answer: If you have more than 75% grass, you may be surprised how your good grass will fill in with four feedings a year at 6 to 8 week intervals. With this option you skip spring seeding (you can always seed in fall if your lawn still needs it). Here is a schedule for the year: Feed your lawn now with Scotts Turf Builder with Halts Crabgrass Preventer. In 6 to 8 weeks after your first feeding, feed again with Scotts Turf Builder Weed and Feed if you have lots of weeds or if you only have a few weeds, your second feeding can be Turf Builder Lawn Food and spot treat your weeds with Ortho Weed B Gon MAX plus Crabgrass Killer OR Roundup For Lawns. Put down Scotts GrubEx sometime in May or June. In 6 to 8 weeks after your second feeding, feed again with Scotts Turf Builder with SummerGuard to control insects. In 6 to 8 weeks after your third feeding, in late summer/early fall, feed with Turf Builder Lawn Food.
If you have questions during the year, the Scotts Help Center folks will be happy to help you.
Overseeding a Lawn with Weeds: Should You Kill Weeds First?
A lawn full of weeds can become even more problematic if you don’t overseed the right way. Overseeding is meant to renew your lawn, fill in any bare spots, and make the turf dense. But, when your lawn is full of weeds, should you go ahead and overseed without killing weeds first?
Overseed your lawn in the fall after killing weeds in late summer. If you’re late, scalp the weedy lawn, rake away all the debris, and spread grass seed. Some weeds will germinate and grow with the grass, but you can control them using a post-emergent herbicide before they spread further.
It is not a good idea to plant and grow new grass over weeds because weeds compete for nutrients and water in the soil, which leads to poor germination and growth of the newly planted grass.
I invite you to join our Lawn Care Group where we all interact, ask, and answer peer questions.
Should I Kill Weeds Before Overseeding?
Kill and remove weeds from your lawn at least 6 weeks before overseeding if you’re using a post-emergent herbicide. Alternatively, remove weeds by hand-pulling manually. Weed killers will affect the seed germination, so, allow enough time as indicated on the product label before planting grass seed.
Since the best time to overseed most lawns is fall, late summer is a good time to put down a post-emergent weed killer. By the time fall comes, it will be at least 4-6 weeks since you applied a weed killer, which is safe for planting grass seed.
How to Overseed a Weedy Lawn
It is best to kill weeds first before overseeding.
Weeds like bare spots and can continue to spread and invade your lawn if you don’t do anything about them. That’s why overseeding helps control them by making your lawn thicker and fuller, and able to choke out weeds.
Overseeding is time and cost-effective, as you don’t have to till and tear apart your lawn. Instead, you’re breathing life back by adding more grass seeds on top of an existing lawn. If done right, this technique lets you grow enough lush lawn that fills in the bare or thin patches in your yard, leaving no room for weeds to grow.
Here’s how to overseed a lawn with weeds:
1. Pull out the weeds manually
Remove weeds from your lawn manually using a weed puller. Pulling weeds out by hand is highly recommended especially if the weeds are grown and visible. Do not apply herbicides on your lawn before overseeding as this can cause poor germination of grass seed.
If you prefer using a weed killer before overseeding, do so early enough to allow time for the herbicide to break down completely before spreading grass seed. Most pre-emergents and post-emergent herbicides have indicated waiting periods before you plant grass seed.
Here’s how to pull out weeds by hand:
- Water your lawn deeply to make the soil soft.
- Pull out weeds by hand or using a weed puller.
- Throw the weeds away from your yard.
In some cases, you may not need to apply a weed killer as weeds like crabgrass usually die off as the weather becomes cooler. If you have annual weeds, just overseed your lawn with weeds late in the fall and allow the new grass to grow. By the time spring comes, your lawn will grow thick and full enough to choke most annual grassy weeds.
2. Mow the lawn on the lowest setting
Set your mower to the lowest setting possible in order to scalp the lawn you want to overseed. Scalping your lawn helps improve the seed-to-soil contact that in turn improves the rate of seed germination. Set your lawn mower’s deck as low as possible – though any setting between 1.5 and 2 inches would be a good option to consider if the lawn does not have too many weeds.
- If your lawn is level, you can set the mowing deck as low as 1 inch from the ground.
- If your lawn is bumpy, set the blades a little higher – up to 2 inches to prevent damaging the blades.
Pro tip: Always bag clippings if your lawn has weeds that have gone to seed to prevent spreading weed seeds all over your yard and worsening the problem.
It is also a good idea, in my experience, to mow right before the rainy week to keep the lawn moist. It makes my mowing job a lot easier as the grass is soft and the thatch easy to remove right before overseeding weedy lawns.
3. Remove grass clippings
Use a rake to remove grass clippings and other debris that’s covering the soil. The process of raking also helps loosen up the top soil in your yard.
If you mowed a little higher, you might have a lot of thatch remaining on the soil surface. Use a heavy duty rake to remove any debris that can prevent your grass seed from staying in contact with the soil for germination.
A good rake can also help you remove any moss that may be growing under the grass in your lawn.
4. Dethatch the lawn
A thick layer of thatch can also cause seed to soil contact problems. Use a dethatcher to break down the thick thatch and then collect the loosened-up trash bag and throw it away on your compost.
Alternatively, run a power rake all over the weedy lawn to loosen up any thatch and tangled-up grass.
When I have a large weedy lawn to overseed, I find it helpful to rent a slit seeder to complete the task in the shortest time possible.
5. Aerate the lawn
By the time it is fall, the soil is usually compacted already, which is why the grass in your yard is growing slowly while the weeds grow faster. After removing the weeds, mowing, and dethatching, core aerate the lawn to allow air, water, and nutrients to be easily accessed in the root zone.
The cores created in the yard will also allow for better seed-to-soil contact as soon as you overseed. This process is better than just sprinkling grass all over the lawn because it improves the rate of seed germination.
6: Spread the grass Seed
Spread grass seed over the prepared area using a lawn spreader. Follow the recommended spreader settings for the type and variety of grass seed you’re overseeding your lawn with to ensure you’ve put down enough make your turf thick and full the next season.
Pro tip: Spread a thin layer of straw to cover grass seed and prevent birds from causing damage. You can also use bird deterrents if you don’t want to cover the grass seed.
For the best results, plant one-half of the grass seeds in one direction and the other half in the opposite direction. I recommend using a lawn spreader for even distribution of the seeds.
Also, you need to make sure the seeds have a good contact with the soil because this helps with proper germination and enhances growth. You can use a water-filled roller or the back of metal rake to establish the recommended contact between the soil and your grass seeds.
7. Gently rake in the grass seed
Raking is important as it helps the seeds come into contact with the soil to germinate properly. If you used a spreader or simply broadcast the seeds with your hand, the grass seed isn’t in proper contact with the soil.
Lightly rake in the seed over the overseeded area to improve contact and promote faster germination. Raking will also prevent water from washing away seeds in your lawn when you irrigate.
8. Water your overseeded lawn lightly
Water the overseeded area lightly to keep the soil moist enough for the grass seeds to germinate and grow. Do not use a heavy sprinkler because it can easily erode the seeds away from the desired area.
Here’s a video on how to prepare and overseed a lawn with weeds:
How to Control Weeds after Overseeding
Weeds may sprout in your lawn soon after your grass seed starts to germinate. At this time, do not apply herbicides yet. Applying herbicides too soon can kill or weaken the young grass shoots.
Wait until the roots have established and the crown matured enough to withstand the strength and effect of the chemicals.
Also, instead of using equipment such as a power rake, which disrupts lawn surfaces, use less disruptive tools such as a hand rake, as they cause less disruption and don’t leave bare patches on the lawn.
Overseed your lawn at the right time to reduce weed competition and enhance the dramatic, successful growth of the overseeding process. You can overseed cool season turf grasses between mid-August and mid-September as a way to fix a weedy yard. These are favorable times for their germination and establishment.
Can I overseed after weed and feed?
It is not recommended to overseed your lawn after applying weed and feed fertilizer. This type of lawn food contains herbicides that can inhibit germination of both grass and weed seeds. If you’ve just put down weed and feed, wait at least 6 weeks before sowing grass seed.
Read the weed and feed product label for the recommended time to wait before reseeding your lawn. Follow the instructions to ensure you achieve a high germination rate when overseeding a weedy yard.
While fall is the perfect time to overseed your lawn and encourage weed control, there are other seasons to overseed provided you understand the risks.
You can overseed in the early spring, but make sure the lawn is well drained for the best results. Weed competition is more progressive and intense as spring progresses. So unless you time the overseeding period before weed germination in spring, doing so at this time may not be effective.
Summer is the least desirable time to overseed your lawn especially if it has weeds. In early summer, the conditions are so hot that there’s a huge demand for irrigation for proper overseeding to be possible. This is also the time when broadleaf weeds tend to thrive, and therefore your overseeding efforts are likely to fail.
Overseeding will make your lawn fuller, and thicker; and improve its pest, disease, and weed resistance. Remember, care for and maintain your lawn after reviving its look and density. Some tips include sufficient watering, proper fertilization, consistent weeding, foot traffic control, and proper mowing.