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How To Apply Pre-emergent For Flower Beds

Keeping weeds under control is an essential task for gardeners. Particularly when they threaten to overwhelm flower beds.

But pulling weeds out by hand can be tiring work. So finding a way to save yourself time and effort is a big plus.

That’s where using a pre-emergent for flower beds comes in. A good pre-emergent applied at the right times of the year can prevent weeds from becoming established. Leaving just the occasional unwanted plant to pull by hand.

What is Pre-emergent?

Pre-emergent herbicide is used for the control of broadleaf weeds and grassy weeds. It aims to prevent weed seed development into a seedling after germination begins.

Using a pre-emergent is one of the best defenses you can have against weeds infesting your flowerbeds. When you apply a pre-emergent to the ground at the right time it can significantly reduce the number of weeds that will grow.

Pre-emergent herbicides are an excellent choice for use in perennial flower beds. And you can use them in beds with a mix of perennial flowers and bulbs. The pre-emergent might cause a small amount of damage occasionally to bulb foliage as it emerges. But it usually recovers. And you can avoid this problem by waiting until the bulbs have come up before you apply the pre-emergent.

There are many pre-emergent products available on the market. They come in two different types, granular and liquid.

How Does Pre-emergent For Flower beds work?

Pre-emergent herbicides create a chemical barrier in the soil. After weed seeds germinate and start to develop roots and shoots, contact with this chemical barrier inhibits further growth.

The pre-emergent chemicals prevent the cell division and production of enzymes needed for the seedling to push its way through the topsoil and develop into a fully-fledged plant.

The pre-emergent herbicide doesn’t actually kill the weed seeds. So seeds that don’t begin germination remain dormant in the soil. And they may germinate in subsequent years. So it’s a good idea to repeat the treatment every year to keep your flower beds weed-free.

Not all pre-emergents control all types of weeds. And some pre-emergents can damage herbaceous ornamentals. So choosing the right product is very important. Both for effective weed control, and to make sure that you don’t damage the plants in your flowerbeds.

Applying Pre-emergent To Your Flower Beds

Flower bed in bloom

You can use a pre-emergent to give broad coverage of annual broadleaf weeds and grassy weeds. But it’s a good idea to identify specific types of weeds that keep appearing in your yard. Then you can make sure the product you choose is effective for that weed.

The best time to apply the pre-emergent herbicide to your flower beds is in the spring to prevent summer annual weeds. And again in late summer to early fall to prevent winter annual weeds.

In the spring, you should aim to apply the pre-emergent a couple of weeks before the weed seeds germinate. This is usually sometime in March or April. A good rule of thumb is to wait for the soil temperature to reach 55°F for several consecutive days.

In the fall, wait for the soil temperature to drop to 70°F. Use a soil thermometer to keep track of the soil temperature changes in your flower beds.

Be aware that you won’t be able to plant new seeds at the same time as you put down pre-emergent. As well as preventing the weeds, it will also prevent any new plants that you attempt to grow from seed.

Instead, you can use rooted transplants to fill your annual flower beds. Give them a chance to become established for a couple of weeks, and then you can apply the pre-emergent.

The pre-emergent only remains active in the soil for a limited time. This varies with the type of pre-emergent. But usually, its effectiveness will end within 2-4 months as it breaks down.

Using A Pre-emergent Correctly

Using a granular pre-emergent is less likely than a liquid pre-emergent to cause damage to the plants in your flower beds. But you will need to water the granules after applying them to the ground.

Watering activates the pre-emergent and allows it to soak into the soil and form the chemical barrier. You can water the pre-emergent yourself. Or apply it before rainfall and let nature do it.

To keep as many weeds as possible out of your flowerbeds, make sure you apply the pre-emergent evenly to the ground around your plants. If you leave any spots untreated, then weeds are likely to appear.

After you’ve watered the pre-emergent into the soil, don’t disturb the area. You will disrupt the chemical barrier and allow opportunities for weeds to develop.

If your flower beds are already mulched, you can apply the pre-emergent on top of the mulch and water it in. The pre-emergent will soak into the mulch and soil.

The Best Pre-emergent For Flower Beds

The safest pre-emergent to use in your flower beds is trifluralin. It controls grassy weeds and broadleaf weeds. And it’s a popular choice with homeowners because it’s less likely to damage ornamental plants than other pre-emergents.

You can find trifluralin in the popular brand ‘Preen’.

Preen Garden Weed Preventer (Amazon)

A Natural Alternative

If you don’t want to use chemicals in your garden, there is also a natural pre-emergent herbicide. Corn gluten meal adds proteins to the soil that can prevent the development of weeds.

You apply it to the ground in the same way as a granular chemical pre-emergent. Make sure to water the corn gluten meal into the soil. It’s very safe to use around ornamental plants in garden beds. But it’s not quite as effective as the chemical options.

Preen Organic Weed Preventer (Amazon)

2 thoughts on “How To Apply Pre-emergent For Flower Beds”

  1. This helped tremendously. I have huge beds of both shrubs and perennial flowers. Age is becoming a factor in how much I can do. Thank you.


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