Spokane County Extension

Garden - Lawn - Landscape

MG Website FAQS

These are some of the questions most frequently asked of WSU Master Gardeners in Spokane County, listed by month. All of our fact sheets are available on this website under Got a Gardening Question?  Other excellent resources are Hortsense  and Pestsense .

For positive identification or diagnosis of plant or insect problems, we recommend that you bring a sample into the Master Gardener Plant Clinic .  You can also send photos by email to mastergardener@spokancecounty.org 




Q - I have red beetles in my cupboards.  What should I do? 

A – There are several types of what we call “stored food pests” in the Inland Northwest. You may not be able to prevent them completely, but here are some tips.  Store susceptible materials in as dry a place as possible.  Use screw lid glass jars or other tightly sealed containers made of material tough enough to prevent beetles from boring through them. Clean up spills and crumbs promptly. Clean and caulk cracks and crevices.  Buy foods in amounts that can be used fairly quickly. 

To treat an existing problem, dispose of any infested material by putting it in a sealed container or bag and placing in the garbage.  Remove all contents from cupboards, shelves or drawers.  Clean thoroughly with warm soapy water or disinfectant and allow to dry before replacing contents. For specific pests see Stored Food Pests.

Q - When is the best time to prune my trees? 

A - Arborists have coined a phrase, “Prune when your shears are sharp”.  They do recommend that you avoid pruning deciduous trees during leaf expansion in the spring and just before leaf drop in the fall. Prune flowering trees or shrubs that bloom in summer or fall on current year’s growth in winter. Prune trees and shrubs that bloom in spring from buds on one-year-old wood, prune just after their flowers fade. For more specifics on seasonal pruning see Keys to Good Pruning .


Q – Is it too early to start tomato plants from seed? 

A – This is the perfect time to think about starting tomatoes and other warm-season vegetables! Our tomato growing season is short, so your goal is to have large, healthy transplants ready for the garden in late May. Detailed information is available from Growing Tomatoes in Home Gardens   and Seed Starting  .

Q - The deer have eaten all the plants I planted last fall.  What can I do? 

A - Choosing “deer resistant” plants would be a wise decision. There are many plants available for use in the landscape that deer tend to avoid.  Commercial deer repellants and fencing may also be necessary.  For a list of appropriate plants see Deer Resistant Plants . (top)



Q - When should I fertilize my lawn? 

A - An easy way to remember when to fertilize is to do it around the holidays: Easter, Memorial Day, Labor Day, and Halloween. There are different types of lawn fertilizers that are appropriate in different situations. For info on lawn care see Lawn Care Basics .

Q - I had weeds in my flower bed last summer.  Is there an easier way to control weeds than pulling them? 

A - Try to keep weeds from going to seed by removing them before they flower, using mechanical or chemical methods.  A layer of organic mulch will help keep weed seeds from germinating as well as maintain stable soil temperature.  Pre-emergents (herbicides that are applied to the soil before weeds appear)can also prevent weed seeds from germinating. For more weed control recommendations see Weed Management. (top)




Q - When can I plant my vegetable garden? 

A – Are you growing from seeds or bedding plants? Sowing seeds directly into the garden is dependent on several factors. For all seeds, soil temperatures must be high enough to allow for germination, which differs from plant to plant. It also depends on how long it takes the crop to mature. See Vegetable Seeding Schedule .

Vegetables fall into two categories – warm season and cool season, which determines when you plant both seeds and transplants. A detailed schedule is found in Vegetable Gardening  .

Q - When should I prune my roses? 

A - The best time to prune roses is when dangers of a hard frost have passed.  Prune away all but 3 to 6 canes on hybrid teas - fewer canes will result in fewer but larger blooms. Vigorous bushes will benefit from thinning, which provides good air circulation and helps prevent fungal disease.  Remove all dead, diseased and damaged wood.  Remove spindly canes, crossing branches and blind shoots that have no terminal flower bud, just leaves.  Cut all canes back to clear white wood.  For info on summer pruning see Rose Culture . (top)



Q - My hostas are being eaten by slugs. What can I do? 

A - Try cultural controls first: Cut down tall weeds and grasses, clean up plant debris, and remove rocks, boards, and other shelters. Encourage predators such as birds, garter snakes, frogs, ducks, and predacious ground beetles. Avoid use of broad-spectrum insecticides that kill beneficial insects. Hand-pick and kill slugs. Slug control products with iron phosphate as the active ingredient have proven to be effective and safe for the environment.

Q - My peach tree has leaves that are all curled.  What caused this? 

A - It sounds like your tree may have a fungal disease called peach leaf curl, which results in the leaves becoming thickened, curled and crinkled.  Diseased fruits may have irregular swollen reddish areas on their surface. In severe infections, defoliation can weaken a tree enough that it may die in 2 to 3 years.  Rake and burn or bag infected leaves. Treatment must be applied as a preventative during the dormant season, just before buds swell.  In eastern Washington a single dormant spray in February will control peach leaf curl. Use a fungicide containing lime sulphur, metallic copper or chlorothalonil.  See Peach Leaf Curl (top)





Q – I have mushrooms growing in a circle in my lawn and the grass looks funny.  Is this a problem?

A - If the mushrooms are growing in circles or arcs of dark green grass that surround areas of light colored or dead grass, you may have fairy ring, a common lawn problem in our area. It is caused by a fungus growing below ground. Treatment consists of aerating the soil well, applying a wetting agent (available at garden stores) over the ring, and drenching the soil with water running from a hose. You may need to repeat the process several times. For detailed instructions see Fairy Ring .

Q – I seem to have a lot of bugs on my trees this year but I don’t like using chemicals.  Are there other alternatives? 

A – Horticulture oil sprays are an environmentally-friendly, effective treatment for a variety of landscape pests, including aphids, leafhoppers, leafrollers, mites, mosquitoes, scales, tent caterpillars and webworms. They work by smothering insects and eggs, so contact with the pest and timing of application are important.  For more information see Horticulture Oil Sprays . (top)



Q - My rose blooms are all brown on the edges when they emerge.  Is this a disease? 

A - It sounds like damage caused by thrip. These tiny brown insects should be controlled early in the season. Control can be difficult because the insects burrow deep within flower buds and under petals. Insecticides labeled for rose and flower insects can be sprayed directly on buds but will only help if they come into direct contact with the insect. Removal of old and infested blossoms can help reduce populations. Remove debris from around plants in fall. More rose questions? See Rose Problems .


Q - I have moss in my lawn.  How do I get rid of it? 

A - Moss in a lawn is usually a cultural problem. Conditions such as too much shade, poor fertility, thatch build-up, soil compaction, and over-watering contribute to moss growth. The first step is to evaluate and correct any of these conditions. If chemical treatment is necessary for severe moss infestation, rake out as much moss as possible and apply a moss control product containing ferrous sulfate. Chemical control will be temporary unless underlying cultural conditions are corrected. For more information see Moss and Algae .  (top)



Q - The ears of my corn have this awful-looking whitish growth.  What should I do? 

A - You may have corn smut.  Common smut and head smut are both fungal diseases. You should remove and discard or burn affected stalks. Planning tolerant cultivars and providing balanced soil fertility are the best controls.  For more info see Corn Smut .



Q - Every one of my tomatoes has a dark blemish on the bottom of the tomato fruit. Some of the areas are sunken.  What caused that? 

A - It sounds like damage from by tomato blossom blight, which is caused by uneven moisture supply that results in a lack of calcium in the plant during fruit formation. It begins as light tan water-soaked lesion on the blossom end of the fruit. The lesions enlarge and turn dark and leathery. The problem may be very severe where the soil has a high salt content, is sandy, or has poor drainage. Container or pruned plants are more likely to suffer. Apply a two-inch layer of organic mulch under plants and water consistently. For more info on tomato problems see Growing Tomatoes in Home Gardens .) (top)

blossom-end rot (BER) in tomatoes







Q - When is my squash ready to pick? 

A - If you’re growing summer squash (zucchini, patty pan, etc.), pick when the fruit is small to moderate in size, the color is good and the rind is easily dented with your thumbnail. Pick winter squash (butternut, acorn, etc.) when the color is typical for the variety and the rind is firm enough it cannot be easily punctured by thumbnail. For tips on harvesting other vegetables see When Vegetables are Ripe .

Q - Every year around this time I see big ugly spiders in my basement. I’ve heard their bite is dangerous. Is this true, and how do I get rid of them? 

A – There are three very similar spiders found in the Pacific Northwest. The bite of the aggressive house spider, Tegenaria agrestis (also called the hobo spider) can cause a severe reaction. Exclude spiders from entering the home by finding and blocking any points of entry. Inside the home, regularly vacuum up spiders and webs. The sticky traps sold in garden stores are safe and effective.  For more information see Aggressive House Spider . (top)



Q - How do I protect my roses for winter? 

A - Grafted roses (those on which a branch with desirable traits is grafted onto the stem of a hardier rose) need protection from Inland Northwest winters at the graft union. Just before the ground freezes, mound soil about 12 inches in and around canes, making sure the graft is completely covered.  Cover with a mulch of fine bark, straw or pine needles. Hardy or “own-root” roses, once established, do not need special winter protection. For more information on winter care of roses see Winterizing Roses .

Q - Can I over-winter my geraniums? 

A - To store plants over the winter, dig before the first heavy frost.  Cut tops back to about six inches, pack close together in deep boxes and cover with light garden soil or sawdust.  Potted plants may be pruned to six inches and left in their containers.  Store in a dimly lit area where the temperature is 40 to 45°F.  Water soil well the first time and check occasionally, watering only to prevent plants from shriveling.  In early April pot the surviving plants in fertile soil, water them well, and place in bright light to develop large, well-branched plants for summer bedding.  For more particulars on growing geraniums see Geraniums . (top)



Q - How often do I water my houseplants during winter? 

A - Most foliage houseplants should be watered sparingly from late autumn to mid spring, letting the soil dry out between waterings.  Most houseplants are dormant for most of the winter, so they don’t use much water. For the same reason, unless houseplants are actively growing, avoid fertilization between mid-October and mid-March. For other houseplant questions see What Can Go Wrong with Houseplants .

Q - I was given an Amaryllis bulb.  How can I force it to bloom?

A – If you received a packaged bulb, follow the directions provided. If not, plant the lower half of the bulb below the soil line in a light potting soil. Keep the pot in bright light at 60-70°F.  Water sparingly until growth begins.  Once the flower stalk appears, rotate the pot twice a week to prevent the stalk leaning towards light.  Water enough to keep the soil moist but not soggy.  For instructions on getting bulbs to re-bloom, see Amaryllis . (top)



Q - How can I keep my Christmas tree fresh? 

A – First of all, buy the freshest tree you can find! When you get the tree home, saw at least two inches off the base to expose fresh tissue and put the tree into water. Your tree stand should be large enough to hold an ample supply of water for the size tree you chose. Do not let the stand dry out or the base of the tree will seal over and stop absorbing water. For more tips, see Christmas Tree and Holly Care .

Q - I’ve heard that deicers can damage my plants. Could you explain why? 

A – We don’t recommend using deicers on walks or driveways that border lawns and perennial beds. Most deicers contain salts and will burn plants and turf in adjacent areas. Rock salt and table salt are harmful to plants and will damage cement and concrete. You can also get contact damage on plants by shoveling snow from treated areas onto them. It is preferable to add traction on ice by applying sand, sawdust or kitty litter on icy walkways or steps. (top)



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