There are a number of weeds that pop up very early in the spring and even start flowering before most other plants have shown any signs of growth. Most of these are spring or winter annuals that come back from seed each year. Spring annuals germinate early in the spring while winter annuals actually germinate during the previous fall, overwinter then resume growth the following spring, flower and die. In most cases, these cool season weeds are more prevalent in waste areas, growing on bare soil.
Common Spring Weeds
Prostrate knotweed (Polygonum aviculare) is one of the earliest annual weeds to germinate. Seedlings can often be found as early as March, particularly along gravel driveways or in heavily compacted soils where it is very common. It is also a common weed in cracks in pavement where it will usually grows flat and spreads out into a mat that may reach 24” in diameter or more. While it can germinate at very low temperatures it can also thrive during the heat and drought of summer, unlike many other spring or winter annuals. It usually doesn’t flower and set seed until the summer months. It is called knotweed because there is a characteristic swelling at each node along the fine, wiry stems.
Bur buttercup (Ceratocephala testiculata) is an early spring flowering, low-growing winter annual that usually flowers once temperatures reach the mid-40s to 50°F then flower and set seed by the first part of May. The plants are quite small, usually reaching no more than an inch or two in height. The flowers are only about 1/4” across and mature into a spiny fruit, which can be quite painful to step on while barefoot. It also tends to grow in large mats containing many individual plants. It can be a tough one to control. I would recommend using combination weed control product in the fall or glyphosate. They will be much more effective on the young seedlings in fall than in the spring. Often this weed will be growing along the sidewalks, in pathways or in other sites with compacted soil.
Henbit (Lamium amplexicaule) may be a winter or spring annual that flowers very early in the spring. It can be a real problem in newly seeded lawns or bare areas in lawns or gardens. Since it is a member of the mint family, the foliage has a minty aroma when crushed or mowed. It has very small pink to lavender flowers that are borne in clusters around the stem at the nodes along the upright stems. The best control in a lawn is to keep the grass healthy. Over-seed bare areas, fertilize if that has not been done in recent years and raise the mowing height to at least 3”. Henbit does provide food for some types of birds so it does have some merit in the garden.
Shepherd’s purse (Capsella bursa-pastoris) is another common winter annual that can be found growing and flowering in both the spring and fall. The common name of shepherd’s purse refers to the triangular shape of the fruit, that resembles an old-fashioned coin purse. This annual produces lots of seed since each of the little “purses” are filled with seeds. The plant starts growth as a rosette of dandelion-like leaves before the flower stem develops that may reach 8 to 12” in height. It is actually a member of the Brassicaceae family so is related to cabbage, kale, broccoli and other related plants. The leaves, seeds and oil is also edible.
Waterpod (Ellisia nyctelea) is a plant often seen growing up in patches in partial shade to full shade locations. Like many of these other weeds, it is commonly seen growing on bare soil or where lawn grasses are thin. It has a distinctive pinnately lobed leaf. It can grow up to a foot tall. It has light blue flowers followed by small fruit that contain four seeds each. It is easy to hoe out when young or pull because it has a weak taproot.
Catchweed bedstraw (Galium aparine) is another very common early spring plant. It is easily distinguished by its finely textured palmately compound leaves and also by the minute sticky hairs which sometimes leads to some of its other common names like Velcro plant and stickywilly. It can be fun to play with as it will adhere to most clothing, particularly if it is soft and fuzzy. But that feature is exactly what allows this plant to be spread around as it hitches a ride on your socks or pants, spreading seeds as it goes. The flowers are quite tiny, four-petaled and white or yellow. During the course of the summer, plants may grow to 4’ in height or spread and become entangled in other vegetation making them quite troublesome. They are fairly easy to pull out when young but you must remove the very base of the plant with some of the roots – the stems can be rather brittle and just break off, only to grow back again.
Managing Spring Weeds
As mentioned in the description of each of these common weeds, they are more prevalent in areas where not much else is growing or along the edges of gardens or lawns. So, the best way to prevent these weeds is to keep other kinds of groundcovers growing or use a mulch to help cover the soil, but often these weeds will be seen growing on the surface of mulch. Pre-emergent herbicides may provide some control but must be applied prior to weed seedling emergence so in many cases would need to be applied in early April for most of these weeds to do much good. Hand weeding, pulling or hoeing are probably the safest methods of removal. Post emergent sprays are another option but must be used with extreme caution as to not damage desirable, adjacent plants. As always, be sure to follow the label instructions. Remember that if weeds are allowed to go to seed, they will just be a more severe problem next year.