Common garden weeds are a large part of our gardens and need to be identified before they manage to sow seed and multiply. If you do keep a strict and thorough weeding regime and keep the spread of seed to a minimum this particular chore will get much easier as the years go by. You will also find by using a ‘do dig’ method and adding compost and manure to the surface of your garden rather than digging it in you will reduce them amount of dormant weed seeds brought to the surface to germinate.
Some of the most difficult weeds to get rid of are the annual varieties as they are such prolific seeders and grow so quickly, I have included the most common varieties below including photos and descriptions. I general I have shown them in their more immature state as this is the point you will need to recognize them and get rid of them.
Chickweed grows to about 5-7 cm high and has a vigourous spreading habit, small white flowers and an extensive root system.
Chickweed is probably the most common annual garden weed. Seeds germinate easily in damp soil in Spring and Autumn or throughout the Summer in a wet year.
Chickweed sets seeds quickly so remove any seedlings you see by hoeing in dry weather or pulling by hand if soil is too damp to hoe. Each plant produces 2,500 to 15,000 seeds which ripen five to seven weeks after the parent plant germinates. Plants are hardy so will survive mild Winters where it can take off quickly and set seed in Spring before you notice!
Fat Hen grows us to 27cm high with broad leaves and small indistinct green/white flowers. Related to tree spinach, fat hen was eaten as a vegetable in neolithic times and is rich in vitamin C.
Fat Hen is found on rich soil so is commonly found in the vegetable garden. Seedlings germinate in dense patches and look harmless at first but quickly grow into large plants if allowed to remain.
Hoeing seedlings when small is the easiest method of control, usually twice if large numbers of seedlings have germinated. Seeds persist for a long time in the soil and will germinate readily even after 20 years when brought to the surface.
Charlock is a common weed when ground is disturbed and grows up to 60cm high with yellow flowers. You will often see large patches of charlock which can easily be confused with the oil seed rape due to its sea of yellow flowers.
Seed are set in 8-10 weeks and will germinate in nearly all seasons especially in Spring. Charlock is a fast growing weed of the brassica family and is easy to how when young or easy to pull our if allowed to grow a larger plant. As with all annuals remove before it can set seed or it will become a much bigger problem. Remember as it is a brassica it can harbour pests and disease from that family so needs to be kept out of other crop rotations.
Groundsel grows to 5-22 cm high, it has lobed leaves and small yellow flowers that form seed heads similar to dandelions.
Groundsel sets seed within 4-6 weeks so you need to be vigilant, one small plant will set hundreds of seeds dispersed over a wide area by the wind. Seeds will germinate throughout the year apart from mid winter and will quickly establish on fertile soil.
If soil is dry or shady the plants will set seed when young so keep an eye out under shade plants like parsnips, courgettes or cabbage. Remember to remove any flower heads after hoeing as they will still make viable seed even if left uprooted on the soil.
Common Fumitory grows to a height of 10 to 40cm on long slender branched stems. The stems support light, feathery leaves and numerous purple-pink flowers.
Fumitory likes undisturbed ground so will be more common on the verges of your garden where the delicate pink flowers are very attractive. The plant is easy to control by hoeing and while it seeds remain viable for a long period of time it is not considered as a particularly invasive weed.
Hairy bittercress is a compact plant growing 3-5cm high with tiny white flowers.
Seeds are set in 4-6 weeks with an explosive seed mechanism by which seeds can be dispersed up to 1m (3ft) away or considerably further if carried by the wind. The diminutive size of the plant also makes it easy to miss allowing it to scatter its seeds unnoticed.
Bittercress is a weed of cool moist conditions so improving drainage will help control. It is also commonly seen growing on the surface of compost in nursery plants and can be unwittingly introduced to gardens from container grown plants.
Prickly Milk (Sow) Thistle.
Can grow up to 90cm high but often smaller with pale yellow flowers.
Seeds are set in as little as four weeks if the plant is in a dry and shaded position. Sow thistle needs to be spotted and removed early as if has a strong tap root making it difficult to eradicate when established and will set hundreds of seeds.
Sow thistle will germinate in a wide variety of conditions throughout the year, even over winter in mild years. There is also a similar perennial sow thistle whose fleshy roots are quick to colonise but can be easily removed as seedlings to keep them under control.
Oxalis only grows about 5cm high but is a very prolific seeder. I had some in my tunnel a coupe of years ago and quite liked the look of is so left it be, big mistake as it’s now all over the place.
Seeds are dropped from barely visible pods before you even notice it’s presence. You need to keep your eye out for this one because once present it will multiply very quickcly. Oxalis is often an unwanted passenger in nursery plant pots.
Shepherd’s purse consists of a cluster serrated leaves with a long slender flower head 5-10cm tall. Before they produce their flower stem Shepherd’s purse can be easily confused with a dandelion leaf.
Seeds are set in 6-8 weeks in green heart shaped seed pods (or purses, hence name). Once the flower stalk has been produced the plant will have grown a deep tap root which can be difficult to remove. Like most weeds, it is a good idea to hoe young seedlings early.
Speedwell is a ground hugging Spring and Autumn weed with prostrate foliage and pretty pale blue flowers.
I have a mat of speedwell under a beech tree on my lawn and am quite happy to leave it there, its low growth habit means it survives the mower.
Speedwell sets seeds in 4-6 weeks but is easy to control by hoeing or pulling out when small. Plants become more difficult to get rid of if allowed to grow into larger clumps but this is unlikely in a busy vegetable garden.