Just when you think your battle against weeds is over for the summer, cooler nighttime temperatures and shorter days spark the beginning of a new crop of your least favorite plants. The question of many homeowners is how did all the weeds get to my landscape?
There are many ways that weeds make it to the landscape. They can be brought in with new soil, mulch, container plants, dropped by birds, delivered on the fur of animals, carried by wind, or on the deck of a lawn mower. If that is not enough to depress you than also realize that regardless of outside sources of weeds, your landscape already has plenty onsite that you don’t even know about.
The deck of a lawn mower can collect plant debris, including seeds, that are spread through the landscape. Photo by Beth Bolles, UF IFAS Extension Escambia County.
In the soil, there is a large number of weed seeds ready to germinate when the conditions are just right. Understanding how your common landscape practices can encourage or discourage the germination of these seeds, can help you begin to manage some weed infestations.
Many of the seeds of common annual weeds are very small. They require exposure to sunlight in addition to the proper temperatures and moisture to germinate. Sunlight is critical though and seeds will not germinate without adequate sunlight. If the small seeds are deep in the soil, you will probably never know they are there. When you turn soil or disturb soil such as when installing plants, you bring the small seeds close to the surface and closer to light. They can then be stimulated to germinate. The next thing you know is that you have an area covered in weed seedlings.
What does this mean for your gardening practices? Try your best to block sunlight from hitting exposed soil. You can do this by keeping a healthy turf, free of thinning spaces. A 2-3 inch layer of mulch in plant beds and vegetable gardens will reduce weed seed germination. Finally when you are installing plants in an established bed, try not to mix soil with surrounding mulch. Seeds will easily germinate within the mulch if it becomes mixed with soil.
It is inevitable that your landscape will have some weeds but a few easy gardening practices can reduce some of your weed frustrations.
A very popular landscape shrub installed by both professionals and homeowners is Loropetalum or Chinese fringe. This shrub offers attractive foliage and flowers along with being evergreen.
When you visit a nursery to select this plant for your landscape, realize that there are now many selections of Loropetalum available. Learn about a few of the common selections in this recording of ‘In the Garden’, with UF/ IFAS Extension Escambia County Horticulture Agent Beth Bolles, so that you are successful at matching the appropriate plant with your landscape needs.
Burrow made by the female Cicada killer. Photo Credits: Beth Bolles, Horticulture Agent
During the summer months, landscapes are alive with insect activity. The majority of insects found in home landscapes are not harmful, although the sight of a few may cause some concern. One insect appears to be threatening but is not is the cicada killer, the largest wasp in Florida.
During the warmer months, female cicada killers make ground burrows that consist of several cells for raising a few young. There is an entrance hole, which often remains open, surrounded by a small mound of soil on one side of the entrance. The female makes this ground burrow after mating and then captures cicadas to add to the individual cells. The cicadas will serve as food for the developing wasp larvae that emerge from laid eggs.
Although the females are able to sting, they are not overly aggressive wasps. The males do make more aggressive flights around people but are unable to sting. When enjoying your landscape, just be aware of ground burrows and the flight of the female wasps into the burrows. If you are lucky, you may even see a wasp with a cicada in tow.
Cicada killers should not be treated in most landscapes. If you are unable to tolerate the wasps, you may reduce their habitat by covering open sandy areas with mulch or a groundcover. This does not completely prevent their ability to nest but will certainly reduce suitable nesting spots. For more information on cicada killers visit: http://edis.ifas.ufl.edu/in573.
This article is being revisited as part of our ‘Best Of’ series. August, 2012.
There is one tough annual plant that thrives in the summer garden and provides bright color in our sun and heat. Portulaca or moss rose (Portulaca grandiflora) is strong performer, even growing well when reseeding in sidewalk cracks and stone walkways. Of course it will be most attractive when used in containers or well drained landscape beds in bright sunshine.
Containers of portulaca brighten an entrance to the herb garden at Escambia County Extension Demonstration Gardens. Photo by Beth Bolles, UF IFAS Extension Escambia County
The thicker, flattened leaves of portulaca make is adaptable to drier conditions. The plants are only about 6 inches tall but branches will spread out a foot or so from the center. The attractive flowers extend just above attractive green foliage in colors of yellow, pinks, and oranges. Portulaca is extremely versatile, making it a good filler in a container or at the edges of flower beds along hardscape areas.
Bright flowers of portulaca reach for the sun. Photo by Beth Bolles, UF IFAS Extension Escambia County
Portulaca will not perform the best when soils remain too moist or days stay overcast for extended periods. Flowering will also be reduced if water is totally lacking. Maintain a balance by providing a quality soil that drains well.
Although many gardeners prefer perennials to annuals, portulaca can provide a big impact in the summer garden for a small investment.
The change in North Florida temperatures from cooler to warmer is making many winter weeds more noticeable as they begin to flower and form seed. Not all of these plants should be considered for mowing or hand pulling. There are several wildflowers that grow in landscape beds and thinning areas of lawns and can be enjoyed before consistent heat returns.
Toadflax flowers are held above the foliage and are light purple. Photo by Beth Bolles, UF IFAS Extension Escambia County
One very delicate wildflower that is growing now is the Toadflax, Linaria canadensis. The leaves are very small and grow low on the ground. Thin flower stalks grow several inches and are topped with light purple flowers. Although toadflax pops up in beds and lawns don’t be so quick to pull it out. This wildflower is a host to the Buckeye butterfly, one of our earlier visitors to gardens. If you look closely you may even see the tiny black, spiny caterpillar eating toadflax leaves. Visit the UF publication on the Buckeye butterfly to learn more.
Adult buckeye butterflies are common in landscapes in early spring and late summer. Photo by Lo Sitton, UF IFAS Extension Escambia County