August Gardening Tips




August is the month to divide iris. Lift the entire clump with a spading fork and discard the oldest, bloomed out sections in the middle.  Cut off the newest 6” “fans” on the outside of the clumps and replant them in an area prepared with compost, peat moss or rotted manure and enriched with some 5-10-10 fertilizer.  Cut leaves back to 6” on the new fans and plant just below the surface of the ground.  Water well and mulch in late fall to protect the plants from severe cold.


Garden centers will have a good selection of fall blooming plants available this month.  Mums, asters and other colorful plants will brighten up your yard or containers on your deck or patio. 


Removing spent blooms on many annuals and perennials will keep plants more attractive and encourage re-bloom.  As the season progresses start to leave flowering stems to provide seeds for birds and to catch snow.


Trees and Shrubs


Late summer is a great time to plant evergreen trees and shrubs.  The new plants will have several months to grow new roots and will beautify your yard this coming winter and all year around.  Evergreen trees such as pines, spruces and firs can help save energy when planted on the northwest side of your home, will provide welcome shelter for winter birds and will be gorgeous when covered with fresh snow.  It is important to water evergreens any week we don’t receive an inch or so of rain up until the ground is frozen.


Few flowering shrubs bloom in late summer but many of the new hardy shrub roses will keep right on blooming into October.  Visit the Shrub Rose Garden at the Landscape Arboretum this month and get ideas on roses to look for at local garden centers and nurseries.




As cooler weather and more regular rainfall arrive lawns benefit from core aeration.  This is especially helpful if you have clay soil or your lawn is subject to heavy foot traffic.  Aeration allows water, air and fertilizer to reach the grass roots and keeps the grass greener, healthier and more drought and stress resistant.


Lawn grasses are cool season plants and late summer and early fall are the best times to start a lawn from seed.  The seed must come in contact with the soil either by tilling or vigorous raking prior to seeding or by using a slit-seeder that cuts slits in the old sod and drops the seed at just the right depth.  Several light waterings each week will get new lawns or re-seeded patches off to a good start.


   Applying lawn fertilizer in late summer will encourage grass plants to spread and form a thicker lawn without           

   encouraging excessive growth in height.


Fruits and Vegetables


August is the peak month for tomato, pepper and onion production.  Harvest the bounty from your own garden or a Farmers Market and enjoy the prizes of this fleeting season or make salsa that will remind you of summer all winter long.


Minnesota Grown apples will be ripening by State Fair time and are available at local orchards, fruit markets and grocery stores through mid-winter.  If you grow your own apples pick them just when the color and flavor peaks and while they are crisp and juicy.  Zestar! is a new University of Minnesota introduction that has great flavor and texture and keeps well for an early apple.