Washington State University

Gardening in Washington State

Archive for August 2015

Why Didn’t My Onions form Big Bulbs?

Onions form bulbs in response to day length or the number of hours of daylight. There are two main types of onions: those grown in northern latitudes that bulb in response to long days, and those grown in southern latitudes that bulb in response to short days. The long-day onions grown in Washington will start to bulb when there are 14 hours of daylight. If they are not planted early enough in the spring, bulbing will begin before the plant grows enough to produce a large bulb. When purchasing onion seed, Washington gardeners should be sure to select only long-day onion cultivars.


Big and small onion bulbs

This material is excerpted from the WSU publication Growing Onions in Home Gardens FS097E.

Submitted by: Marianne Ophardt, August 31, 2015


Harvesting Potatoes for Storage

Potatoes that will be stored through the fall and winter should be harvested when mature. Depending on the cultivar, this will be approximately 70 to 120 days after planting.



The vines will start to die back in late summer or early fall, when the tubers are mature. In regions where wet fall weather may hamper harvest, potato plants may be cut off at the soil surface using pruning shears. Stop irrigating after the tops die back naturally or you cut them off. This promotes wound healing and tuber maturation.

Dig your potatoes approximately 2 weeks after the vines have died back or been cut back. Waiting allows the skin to thicken, so they will not injure as easily when dug.

This material is excerpted from the WSU publication Growing Potatoes in Home Gardens FS118E

Submitted by: Marianne Ophardt, August 24 2015


2015 Winter Damage to Evergreens: East of the Cascades

Early Fall 2014 proved to be unseasonably warm and dry east of the Cascades. Plant respiration continued at a higher rate than normal for this time of year and, in many cases, irrigation was winterized. This meant that some evergreens were unusually water stressed. The warm and dry fall was followed by unseasonably low temperatures in November. This unusually hard freeze, coupled with the drought stress, meant that many evergreens suffered tissue damage.

Some of the plants seen with winter cold damage are dwarf arborvitae, hinoki cypress, boxwood and ponderosa pine.

Fig 1

Figure 1. Dwarf arborvitae leaf and twig winter cold damage, ranging from leaf necrosis to branch dieback.

Fig 2

Figure 2. Hinoki cypress suffering complete winter kill


While leaf necrosis and branch dieback can be unsightly, most of the plants with this winter cold damage will survive. If the leaf buds were not damaged the plant will grow out of the problem. It is important to wait until late spring or early summer to determine the full extent of the damage.

Fig 3

Figure 3. Boxwood showing leaf and twig winter cold damage along specific areas of the plant, such as the top or side.

Fig 4

Figure 4. Ponderosa pine needle winter cold damage ranges from minor needle tip damage to, in severe cases, complete needle necrosis.




Prune out dead branches to clean up plants. Let the new growth expand and grow to fill in void areas. Careful pruning over the next few years will usually bring back the normal healthy appearance of the plant. If branch dieback goes into the dead zone of conifers, the plant many not return to its original appearance and will need to be replaced.

Submitted by: Paula Dinius, August 13, 2015


Do woody mulches attract termites, carpenter ants, and other pests?

Many wood-based mulches are not attractive to pest insects but are actually insect repellent. For instance, cedar (Thuja) species produce thujone, which repels clothes moths, cockroaches, termites, carpet beetles, Argentine ants, and odorous house ants. In general, termites prefer higher nutrient woody materials such as cardboard, rather than wood chips.

Courtesy Wikipedia

Termites – courtesy Wikipedia

For more information on wood chip mulches, see “Using Arborist Wood Chips As a Landscape Mulch” WSU Extension Fact Sheet FS160E.

Submitted by: Linda Chalker-Scott, August 10, 2015


Gardening in Washington State, Puyallup Research and Extension Center

All publications linked to this website have been peer-reviewed
© 2022 Washington State University | Accessibility | Policies | Copyright | Log in