How Fast do Weeds Grow?
My garden is living proof that plants need food, water and sunshine to grow. I provided water and fertilizer but the backyard was sunny for only a part of the day. This year, we moved the garden to the side of the house and WOW! It turns out a lot more sun spurs a lot more growth. Our plants are doing well. Unfortunately, so are the weeds. Which makes me wonder, why do weeks seem to grow so quickly?
“Actually weeds don’t grow faster than other plants, weeds just time things a lot better,” said Steve Bowe, a group leader in Biology Research and Development at BASF told me.
Consider the carrot, which we tried to grow in our garden. The seed package says carrots will germinate in around 20 days. You can assume if growing conditions are perfect it may be a few days faster. If conditions are less than ideal, germination may take a few additional days. Whatever the case, weeds such as chickweed and pigweed take advantage of that.
The weeds sprout in a few days and by the time the last carrot has sprouted, the weeds will have bloomed and seeded. It can happen so quickly that the initially slow growing carrot has no chance and it completely smothered. There’s one more challenge for the carrot. The weeds produce enormous amounts of seeds, which sprout on the surface and can grow in a wider range of conditions. It’s another reason the carrot doesn’t stand a chance.
So what is a poor gardener to do? Farmers rely on herbicides, which doesn’t make sense for a home garden. BASF’s Steve Bowe advises hoeing the top one to two centimeters of soil. There’s no reason to go deeper and risk damaging the roots of your crop. Hoeing the very top of the soil means what has sprouted already will dry out, and the loose and dry top layer will stop other seeds from sprouting. It also should slow the evaporation of water from the soil. Less evaporation means higher soil temperature, and thus faster growth of your favorite vegetables.
Frank Graff is a producer/reporter with UNC-TV, focusing on Sci NC, a weekly science series. In addition to producing these special segments, Frank will provide additional information related to his stories through this North Carolina Science Now Reporter’s Blog!
How Fast do Weeds Grow? My garden is living proof that plants need food, water and sunshine to grow. I provided water and fertilizer but the backyard was sunny for only a part of the day. This
Dr. Universe: Why do weeds grow sooo fast? – Leah, 9, British Columbia
If you’re like me, you’ve picked up a little dandelion fluff ball and blown the seeds around. Weeds like these make a lot of seeds. They get picked up by the wind and planted far and wide. And as you observe, they grow pretty fast, too.
My friend Tim Miller is a researcher at Washington State University working to help stop weeds from making life difficult for plants we would rather have. Sometimes, weeds are bullies to other plants.
“Weeds are simply plants that are able to compete well with the plants we want to grow,” Miller said. “Imagine two plants growing side by side. Let’s say one is a squash and one is a weed.”
He explained that these plants compete for resources both of them need to grow: sunlight, water, nutrients, and space.
“The weed is able to grab those resources before the vegetable plant can get them, so they tend to grow a little faster and a little better than the vegetable does,” Miller explained.
A race to the top
The weed seeds are already in the garden soil. They wait for just the right temperature and moisture conditions. So, when you plant your seeds, the weeds race out of the ground before whatever you planted can even get started.
Sometimes gardeners help their vegetables by growing them in pots and then transplanting them into the garden. That gives the veggie a head start against the weed.
Miller said some weeds grow from a root that has been alive for many years. These kinds of plants are called perennials. The grasses in your lawn are also perennials. Perennial weeds grow especially fast and are much harder to kill than annuals, which have to grow from seed every year.
Perennial roots have lots of energy in them from previous years of growth. Miller explained that energy helps the shoots grow very quickly. This makes perennial weeds particularly hard to control.
Seeds in the breeze
Dandelions are one kind of perennial. Each dandelion fuzz ball has as many as 100 seeds that travel in the wind. If a dandelion plant makes 10 flower heads, that’s 1,000 seeds waiting to sprout wherever they land. How many dandelions do you think you have in your lawn? If there are 50 plants, just think of those 50,000 new dandelions that can sprout from all those seeds. It’s no wonder weeds are so hard to control.
While they may be bullies to plants, weeds have also inspired some interesting ideas. The engineer who invented Velcro was inspired by those prickly weed burrs that stuck to his clothes and his dog’s fur. You never know what might inspire a great idea or when that idea will strike.
My friend Tim Miller is a researcher at Washington State University working to help stop weeds from making life difficult for plants we would rather have.