New Hampshire weeds – 20 most common

New Hampshire is a beautiful state known for its lush greenery and picturesque landscapes. However, even the most well-manicured lawns and gardens can fall prey to pesky weeds that seem to pop up overnight. These unwanted plants can quickly take over your yard, causing damage to your landscaping and making it difficult to maintain the look you desire. In this guide, we’ll explore some of the most common weeds found in New Hampshire:

garden weeds

Table of Contents

New Hampshire Weeds

Name of Weed Family
White clover Apiaceae
Dandelions Asteraceae
Yarrow Asteraceae
Witchgrass Poaceae
Quackgrass Poaceae
Goosegrass Poaceae
Moneywort Primulaceae
Mallow Malvaceae
Speedwell Plantaginaceae
Crabgrass Poaceae
Purslane​ Portulacaceae
Lambsquarters​ Amaranthaceae
Pigweed​ Amaranthaceae
Chickweed​ Caryophyllaceae
Shepherd’s Purse Brassicaceae
Creeping Charlie Lamiaceae
Canada Thistle Asteraceae
Bindweed​ Convolvulaceae
Nutsedge​ Cyperaceae
Plantain Plantaginaceae

White clover

While there are several types of clovers, white clovers are prevalent in Utah. You can recognize white clovers by their white, puffy blooms and leaves, which generally have a pale white “V” on them. The weed species grows low to the ground and is capable of quickly covering an entire lawn. White clover grows actively during spring, summer, and autumn. It thrives in lawns that are nitrogen deficient.

Type

Perennial Broadleaf

Family

Apiaceae

Control

By maintaining the lawn properly, you can prevent the weed from growing and spreading. A pre-emergent herbicide application is recommended to control the white clover invasion. For eradicating established weeds, it is important to use a post-emergent herbicide application.

early fall white clover

Dandelions

Dandelions are a popular perennial garden weed, that is hardy. It can withstand freezing temperatures. The dandelion blooms emerge from a single stem. Its flat, spear-shaped leaves produce a milky sap. You can see seed heads emerging from flowers. Children usually pluck this seed head and blow it across the garden, and this is one of the ways the weed quickly spreads its seeds.

The weed species prefers acidic soils. It is not easy to control these weeds because the far-flung seed pods can sprout hundreds of new shoots.

Type

Perennial broadleaf

Family

Asteraceae

Yarrow

Yarrow is a broadleaf weed that grows rapidly. You can identify this weed by its flat-topped clusters of white flowers. The leaves are greyish-green in color and have three to five leaflets with sharply serrated edges. Yarrow has a strong scent, making it easy to identify the weed when it blooms in summer and early autumn.

Type

Perennial broadleaf

Family

Asteraceae

Control

Weed prevention is the best approach for controlling this weed species. If you see any yarrow starting to grow, it is important to remove them before they spread its seeds. A pre-emergent herbicide application can also be used to prevent new yarrow plants from sprouting. When dealing with existing weeds, a post-emergent herbicide application is the most effective solution.

Dandelions

Witchgrass

Witchgrass is an annual weed species, which grows to a height of two-three feet. It has long, slender leaves that are yellow-green in color. Witchgrass produces several small seeds each season and can quickly spread its seeds if not removed early on.

Type

Annual grass

Family

Poaceae

Control

Weed prevention is the best method to best control this weed species. If you see witchgrass growing, it is important to remove them as soon as possible. A pre-emergent herbicide application can be used to prevent new witchgrass plants from sprouting. When dealing with existing weeds, a post-emergent herbicide application is the most effective solution.

noxious weed witchgrass

Quackgrass

Quackgrass is a perennial weed that has v-shaped leaves and grows to a height of two feet. It produces small, white flowers during the summer months. Quackgrass spreads quickly because its creeping roots can produce new shoots in other locations. The weed species prefers moist soil conditions and will usually die out when the weather becomes too dry.

Type

Perennial grass

Family

Poaceae

Control

Weed prevention is the best approach for controlling this weed species. If you see any quackgrass starting to grow, it is important to remove them before they spread their seeds. A pre-emergent herbicide application can also be used to prevent new quackgrass plants from sprouting.

quackgrass

Goosegrass

Goosegrass is a summer annual grass that sprawls on the ground to form a mat-like rosette. Its leaf blades are thick and dark green with well-pointed seed heads. The finger-like spikes contain the seeds, and a single plant bears nearly 50,000 seeds!

The annual weed species has a well-developed root system, which makes it difficult to dig the plant out from the ground. Goosegrass thrives in compacted soil with no vegetation.

Type

Annual Grass

Family

Poaceae

Control

Keeping your lawn healthy is key to preventing goosegrass invasion. Core aeration is recommended every year because these weeds grow well in compacted soil. The use of post-emergent herbicides proves to be effective to get rid of established goosegrass.

Goosegrass weed

Moneywort

Moneywort, also known as creeping jenny is a hardy cool-season perennial with a widespread root system. Its flowers are trumpet-shaped and bright yellow in colour. Borne in pairs, the oval to heart-shaped leaves are present all along the stems. The weed produces vines that either climb and curl along nearby structures or creep along the ground. It is mostly found in wet grasslands, wet woods, and along ponds and riverbanks.

Type

Perennial

Family

Primulaceae

Control

While you can reduce the spread of Moneywort by manually removing it from your garden, unfortunately, you may not be able to get rid of this weed completely by manual control, because its roots extend several feet under the ground, and the seeds can live for many years. However, it is possible to hinder the spread of this weed by cutting off its top and hoeing the area combined with herbicide application. 

Creeping Jenny

Mallow

Mallow is a summer annual weed which has deeply lobed leaves and produces flowers that are usually white but may be pink or purple. Its roots form long taproots that can reach depths of up to four feet below the soil surface. Mallow spreads quickly when in favorable conditions as it produces hundreds of seeds each season.

Type

Annual

Family

Malvaceae

Control

Prevention is the best way to control mallow infestations. Weed-free planting beds can help prevent mallow from getting established in your lawn. If you see any existing weeds, they should be removed before they spread their seeds. A pre-emergent herbicide application can also be used to prevent new mallow plants.

mallow weed

Speedwell

Speedwell is a low-growing weed with long-stemmed, bright blue flowers that bloom early in the year, generally from March to May. It can form dense patches in a garden or lawn. The weed has slender stems and small leaves. Its stems are almost horizontal, well-branched, and hairy.

The weed species prefers moist conditions and thrives in loamy soil. It is found in grassy places including meadows, lawns, and pastures, as well as in waste grounds, woods, and hedgerows.

Type

Annual or Perennial

Family

Plantaginaceae

Control

Specific broadleaf weed herbicides are generally used to control speedwells. Pre-emergent herbicides can be used to control annual speedwell species. Herbicides containing the combination of triclopyr and dicamba tend to be effective for postemergence control of these weeds.

Speedwell

Crabgrass

Crabgrass grows low on the ground and typically spreads out horizontally like a crab’s legs. It has flat, green leaves pointing outward and finger-like florets. The stems are spreading and branched. Its roots develop at the nodes on prostrate stems.

The weed prefers dry and hot conditions. It can be found in the disturbed areas of weedy meadows, prairies, lawns and gardens, fields, vacant lots, grassy paths, and along roads and railroads.

Type

Annual grass

Family

Poaceae

Control

It is possible to keep crabgrass growth and spread in check by regularly mowing the lawn. A pre-emergent herbicide application is the best way to prevent the weed from taking hold in a lawn or garden. The herbicide should be sprayed in the spring when crabgrass grows actively.

prefer warm soil

Purslane

Tasty and succulent, purslane (or Portulaca oleracea) is a leafy green vegetable with red stems, small green leaves, and an impressive 93% water content. It can be enjoyed raw or cooked in various dishes under many of its other names such as pigweed, little hogweed, fatweed, and pusley.

It is considered a weed by many but is a healthy, nutritious plant. Purslane contains more omega-3 fatty acids than any other leafy vegetable, plus vitamins B and C, iron, magnesium, calcium, and potassium.

Type

Annual Broadleaf

Family

Portulacaceae

Control

Eliminating purslane can be achieved by both manual extraction or chemical control methods. Rainfall and irrigation can help conserve soil moisture, which will reduce its spread. Additionally, broadleaf herbicides such as 2,4-D or dicamba (Weed Master) can also be used to effectively control it.

Purslane

Lambsquarters

This weed species is an annual with a low to medium-growth habit and small, white flowers. It is often found in gardens and lawns where it can quickly spread if not controlled.

Lambsquarters have diamond-shaped leaves that are smooth on the upper surface and whitish beneath, as well as small greenish-white flowers that are grouped together in clusters.

Type

Annual Broadleaf

Family

Amaranthaceae

Control

For effective control of this weed, consider using selective broadleaf herbicides such as 2,4-D or dicamba (Weed Master). If physical removal is preferred, make sure to remove all parts of the plant, including its roots.

Lambsquarters

Pigweed

Pigweed, also known as red root, is an annual weed with a low to medium growth habit. It has reddish-green leaves that are often mistaken for those of spinach and can be found in waste places and gardens all over the world. The flowers form slender spikes about 2 cm long and have five small petals. The weed is easily identified by its pungent smell when crushed.

Type

Annual Broadleaf

Family

Amaranthaceae

Control

The best way to control pigweed is through chemical means such as herbicides containing dicamba or glyphosate (Roundup). Hand weeding can also be successful if done properly, ensuring that all parts of the plant, including the roots, are removed. Regular mowing can also help to keep pigweed from spreading by preventing it from flowering and going to seed.

pigweed

Chickweed

Chickweed is a low-growing weed, reaching a height of 30 cm. It sprawls on the soil surface to form mats of foliage. It can be identified by its simple, frosty leaves and white flowers with five petals.

The weed species grow well in the winter. It prefers cool, moist conditions, and does not tolerate hot temperatures. Chickweed can quickly spread over the bare land in a garden or lawn.

Type

Annual broadleaf

Family

Caryophyllaceae

Control

Chickweed can be removed by hand-weeding. However, it is time-consuming. When it comes to chickweed, prevention is the better option. When you notice a weed showing up in your garden or lawn, pull it out immediately. Appropriate herbicides and selective weedkillers can be used to control chickweed invasions.

Chickweed close up

Shepherd’s Purse

Shepherd’s purse is a weed characterised by many stems and triangular or heart-shaped seed pods. It has many tiny, four-petaled flowers on the upper part of the stems and branches. The weed species can be found in disturbed areas, roadsides, gardens, trails, and old homesites across Wisconsin. It reproduces by dispersing seeds via water, wind, animals, and vehicle tyres.

Type

Annual

Family

Brassicaceae

Control

The primary means of controlling shepherd’s purse on a lawn is by hand pulling or using a suitable weeding tool. This is the best option if the infestation is in its beginning stages. However, to remove established weeds, using a contact weed killer in early spring before the flowering period is recommended.

Shepherd's Purse

Creeping Charlie

Also known as ground ivy, the creeping perennial weed, gets its name from the creeping stems that sprawl along the ground. The weed can be recognised by its green vine, round leaves, and purple flowers. Creeping Charlie is a low-growing weed that forms a mat-like cover. The weed species thrives in moist areas such as hedgerows, waste areas, woodland margins, and shady locations. It can also survive in sunny locations.

Type

Perennial

Family

Lamiaceae

Control

Creeping Charlie grows well on an unhealthy lawn. Therefore, maintaining a healthy lawn is the best defence. Once the weed takes root and invades your lawn, it’s not easy to eradicate it. Most broadleaf herbicides don’t work well to remove these weed plants. Hand-pulling can be done to remove just one or two weeds. However, when there is a large patch, use a professional-grade herbicide in the autumn season.

persistent perennial grass

Canada Thistle

Canada thistle is a perennial weed found in almost every region of the US and Canada. This weed stands out from other perennial weeds, because it has stout, upright stems with spines on the edges. The flowers of this plant are small and purple-coloured, growing in clusters on spikes at the tip of each stem. The roots are deep-reaching and can spread through underground rhizomes.

Type

Perennial weed

Family

Asteraceae

Control

The best way to control Canada thistle is to prevent it from spreading. Pulling or digging out the plants as soon as they appear will help reduce their numbers. For an infestation too big for that, herbicides containing 2,4-D can be used to kill Canada thistle. Also, mowing the weeds before they flower will help prevent them from going to seed. However, keep in mind that Canada thistle is difficult to get rid of completely, so repeated treatments may be necessary.

perennial plants

Bindweed

Bindweed is a climbing vine that can get out of control. It is often confused with morning glory, due to its pretty, lilac-colored, trumpet-shaped flowers. The climbing weed wraps itself around any structure it gets a hold of. It is capable of completely covering the other plants, depriving them of sunlight, and eventually choking them. Bindweed prefers dry soils.

Type

Perennial

Family

Convolvulaceae

Control

As bindweed prefers dry soil, you can control the growth of bindweed infested areas by watering the flower beds and garden regularly. To manage a large bindweed infestation, start by irrigating the area. When the weeds grow well, treat the area with glyphosate application before planting desirable plants. After that, use a mulch or pre-emergent herbicide to control the regrowth of bindweed.

garden beds Bindweed

Nutsedge

Nutsedge, also commonly known as Nutgrass, is a perennial weed with bright green leaves and sharp edges. It grows in clumps with yellow flowers that emerge from spikes or “nuts” located at the top of the plant. Nutsedge prefers moist soil and can spread rapidly throughout lawns.

Nutsedge might go unnoticed at first because its seeds look like out-of-season Bermuda grass and thatch.

Type

Perennial Grass

Family

Cyperaceae

Control

Regular maintenance is key when controlling Nutsedge. To achieve a healthy lawn, it is important to have proper mowing and watering schedules. Additionally, post-emergent herbicides can help target established weeds like Nutsedge. Be sure to apply the herbicide during the early stages of growth and follow up with another application as needed.

Nutsedge

Plantain

Plantain is a low-growing, broadleaf weed. Its oval-shaped leaves grow circularly. Greenish flowers can be seen spiking up from a central rosette. The buds and blooms look alike and run along lengthy stalks.

The weed species prefers heavily trafficked areas. Well, it’s a tough weed that can survive almost any condition.

Type

Perennial Broadleaf

Family

Plantaginaceae

Control

Pulling up the weed can be an effective way to fight it. However, the plant should be pulled out from the root, making sure that no root is left behind in the soil. It’s because, if any part of the root is left, the weed can regrow. Aerating the lawn and keeping it lush without any bare spots is recommended to keep the plantain weed under control.

Plantain
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Oliver Wright
Oliver Wright

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