Fall is here, and you may have gardening questions. To ask one, simply go to the OSU Extension website, type it in and include the county where you live. A photo is very helpful.
This clematis was beautifully green when planted last spring but has continued to yellow.OSU Extension Service
Q: Can you help me with my evergreen clematis? It was beautifully green when I planted it last spring but has continued to yellow. I’ve thought overwatering, but it doesn’t get any more water via drip than the rest of my landscape. I thought perhaps magnesium deficiency and have tried an Epsom salt dilution twice with no noticeable improvement. Also, iron and extra nitrogen over the months it has been planted. I had a confederate jasmine I had previously planted that didn’t thrive in this spot as well. Any suggestions would be appreciated. I don’t think it will survive the winter. – Marion County
A: Sometimes the problem is not a deficiency of nutrients but that the soil pH is too high or too low. Clematis armandii prefers a pH of at least 6.0. Here’s more information about that. It’s not possible to guess what the soil may need, or how much of any amendment is needed to correct the problem. Adding unnecessary amendments can degrade the soil and groundwater. I suggest getting a laboratory test that will establish a baseline of nutrients and other data, indicate what may be needed, and importantly how much should be applied. Extension does not provide soil testing services, however, here are links to Oregon labs as well as another that is reported to be especially good for home gardeners. Take a look at this, this, this and this for more information about how to take a soil sample, labs in Oregon and other information.
Be sure to take a good sample (per the info above) and let the lab know what you are planting. – Lynn Marie Sullivan, OSU Extension Master Gardener
How to get rid of lace bugs
Q: I would like some guidance on how to best treat my backyard that is infested with lace bugs. I need almost all if my shrubs to be treated. I have over 50 plants to treat. – Lincoln County
A: Most plants do not get lace bugs. I’d need photos of other plants to diagnose their problems. For the lace bugs (plants affected include rhododendrons, azaleas, oak, pyracantha, elm and hawthorne) at this point in the growing season, you should try to use a strong stream of water to try to dislodge as many pests as possible. Using a hose attachment like Bug Blaster can help reach pests like lace bugs on the underside of leaves. It’s also very important to keep the shrubs watered and fertilized. Healthy shrubs are better able to resist lace bug attacks. Lace bugs overwinter as eggs in brown patches on the underside of leaves so you should try to remove any leaves with these eggs along the midrib. Here is some information from the Pacific Northwest Insect Management Handbook. It describes cultural controls and refers to chemical controls that you may consider. If you do consider chemical control, please read and follow all label instructions. If that includes any systemic insecticide, do not use until all blooming on the affected shrubs and adjacent shrubs has ceased. This will help ensure pollinators such as bees are not negatively affected. – Bill Hutmacher, OSU Extension Master Gardener
What’s the best watering system for raised beds?
Q: I need to re-do my 16 raised vegetable beds’ watering systems. Currently they have only two pop-ups per bed (beds of either 6-by-10 feet or 4-by-6 feet) and they get the leaves not the roots wet, so all summer I have been hand watering and this cannot continue next year. Because I am only to re-do this once – what is the best type of watering system to put in? – Clackamas County
A: Interestingly, I have the exact same number of beds as you so here is what I, well actually my husband, sets up for us each year: We water half the garden with an overhead system that is set up on a timer we can change to reflect the weather patterns. One overhead sprinkler covers half the beds where we plant things that don’t really matter if the leaves get wet: lettuce, spinach, Swiss chard and other leafy crops, peas, broccoli, cabbage, cauliflower, beets and turnips. The other eight beds get drip irrigation in lines from a central hose. These crops are carrots, squash, tomatoes and beans. Some of them get a drip line along a row (carrots and beans) and some get individual heads where the main plant grows (squash and tomatoes). We have a timer that splits into two feeders so that the overhead can be set differently from the drip system, but both systems come off the same hose bib. Since my beds are laid out in roughly a square, I rotate the plants in the beds 90 degrees each year and move the system (which we take in in the winter) 90 degrees as well. This means I’m growing the same crops in the same beds every four years, but never two years in a row. This helps with disease and insect pests. I hope this gives you an idea for avoiding hand watering. There is a bit of initial output for the drip system, but it’s well worth it in the long run!.– Rhonda Frick-Wright, OSU Extension Master Gardener
Do raised beds need to be protected from rain over winter?
Q: I’m planning to sow cover crops in some of my raised beds, but others will just have compost/mulch as a top layer for the winter. Do I need to cover my beds further from rain? I would like to ideally be able to get sowing early spring, as well as enjoy my over-wintered harvest. – Multnomah County
A: If you aren’t planning to grow any food crops over the winter, you don’t need a hoop house/high tunnel to protect the soil. Some plants that are considered “cool-weather crops” are helped by protecting them from snow and ice, but your cover crops don’t need that, and the mulch will help the rest. Here is an article about these structures, which you might want to consider erecting in the spring, so you can get a jump on direct-seeded plants and transplanted seedlings that need protection from the elements. – Kris LaMar, OSU Extension Master Gardener
How to get rid of oxalis
Oxalis can be a very difficult plant to eliminate from the garden.OSU Extension Service
Q: I am attempting to get an old garden back into shape. We have a huge problem with oxalis in one of our raised beds. I do not want to use chemicals to treat as this is our vegetable garden. Any suggestions as to how to get rid of this annoying weed? – Deschutes County
A: As you have experienced, oxalis can be a very difficult plant to eliminate from the garden. Oxalis flowers and produces seeds heavily in the spring and summer but can produce both all year long. Small plants can easily be handpicked or dug as they appear before they flower or form seeds. Removal of all vegetative portions of the plant, including roots and rhizomes, is important. Rhizomes can be easily removed when the soil is moist. Do not place the weeds with seeds in compost bins for reuse in the landscape. A light layer of mulch in landscape beds and around flowers and shrubs will aid in preventing further germination of oxalis seeds. The seeds require light for germination, so limiting light to the seedbed with mulch will reduce the numbers of new oxalis plants. Here’s more information. – Susan Preston, OSU Extension Master Gardener