Season 2 • Episode 12 - June 26, 2023

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June marks the beginning of summer and things in the garden are heating up, and I’m not just talking temperature! After the bright beautiful colors of spring have faded you might be seeing a few plant problems and have concerns about what to do to address those problems. As always, we turn to our friend, retired Oregon State University Extension Agent Jan McNeilan to get some tips on working in the early summer garden.

Jan met us at the Portland Nursery location on Stark Street in Portland. We were surrounded by great plants and eager summer shoppers, many of them listening in as we recorded the podcast.

The first tip that Jan offered was deadheading your rhododendrons. Yes, you can, but do it soon. Deadheading is the removal of the dead blooms. You can do that now but know that the plant will start setting buds in mid to late summer for the blooms for next year. You can also do some hard pruning to get your plants into a manageable shape, but those hard cuts will cause the plant to go without blooms for a year or two. The best time to deadhead your rhodies and lilacs is right after they bloom. In fact, that is true for most of your spring blooming perennials. Cutting them back, while it probably won't the plants, can cause them to grow an extra season or two before the blooms return. You can also fertilize when you see new growth on your plant. If you do fertilize, make sure that you give the plant a good watering and work the fertilizer into the soil to help release that fertilizer to the plant. Avoid fertilizing and pruning during extreme heat so you don’t stress out your plant. Another way to help your plants during the summer is to add mulch to your garden beds. A good layer of garden mulch will protect the plant by holding in the moisture, provide a nutritional boost to the plant and help with weed suppression. Jan did give us a tip on how to mulch. Make sure your mulch is not piled up around the base of the plant. If it is too thick it can block the water from reaching the root zone of the plant.

Judy brought up strawberries next. What should you do with your strawberries once they are done fruiting? Right now you can clean up the dead and dying leaves. You can also cut the runners and replant the little plants that are attached to the runners back into your strawberry bed. In late August you can cut back all the foliage on the plants and fertilize them in anticipation for the fall and winter. All this talk about strawberries had Ryan bring up another question. Is it too late to plant some of your fall fruiting veggies? Jan, mentioned that last year she planted her tomatoes on June 22nd and she still had tomatoes by the fall. Yes, you can get some of those crops in the ground, though it will speed things up if you get plants from your local garden center and not start them from seed. The summer heat and even watering will help those ‘late-bloomers’ catch up and fruit before you know it. We also talked about planting your fall cole crops (broccoli, cabbage, cauliflower and kale) in mid- to late July for a bountiful fall and winter harvest. Ryan talked about succession planting with onions in his garden. He planted onions earlier and now he is planting them again, a few weeks later. This allows him to harvest onions at two different times instead of one big crop all at once. You can do this with lots of your garden vegetables. If you are looking for seeds, pick those varieties that are ‘short season’ varieties. They will mature quicker and you can enjoy two or more harvests before winter.

The next topic was lawns. In the summer, long, green lawns are the goal of many homeowners, but many get discouraged when their lawns turn brown during the summer heat. Jan wanted to let them know that the lawn is not dead from the summer heat. The grass just goes dormant. It will return to green when the fall rains return. The only problem is with weeds in the dormant lawn. Weeds will see an opportunity to take over the dormant summer lawn when your grass is weak. Watch for them and remove them once you see them. If you do want to have a green lawn in the summer, water it less frequently, but deeply. Instead of watering every day, water every few days but allow the water to soak into the ground so the roots of your lawn grow deeper. Also, set your mower to a higher setting. The longer grass will shade the roots and allow them to stay cooler and retain moisture. You should also have a schedule for fertilizing and possibly applying lime to ‘sweeten’ the soil (get a soil test to see if this is necessary). You can check to make sure that the water is getting down into the root zone by using a screwdriver and pushing it into the ground. If the soil is dry and hard, then you may need to adjust your watering accordingly. Aerating your lawn will also help get the water down into that root zone as well. Deep watering will also help your potted plants and containers survive the heat, though those might need a little more attention to keep them happy and healthy. If you have patches in your lawn and need to reseed, scratch up the surface of the soil and spread lawn seed in that area, then cover it with a light layer of potting soil or peat moss, and then keep moist for 10 days to 2 weeks. Spread the seed into the existing lawn so it helps blend in the new and old patches. Mow the new lawn after it gets 3-4 inches tall.

Summer is also the time for watering. We talked a little bit about it earlier, but Ryan brought up the fact that sometimes your sprinkler system doesn’t always reach where it needs to go. Jan recommended that you test your watering system so you know where it is watering and the areas that are being missed. You should keep checking it during the summer months and into fall, as plants may have grown up and blocked part of the watering pattern.

If you are applying lawn or garden chemicals Jan also recommended that you read the labels, know what you’re applying and in what amounts. The problem that a lot of gardeners have is that they apply chemicals too often and for problems that they are not having. First, diagnose the problem (if there is one) and then figure out a solution. It could require a synthetic or organic application, or maybe none at all. If you do have a problem and need to treat it, read the label and follow all instructions. The label is the law when it comes to garden products. Judy talked about how she tries to get her weeds pulled before they become a problem. Ryan brought up home-made remedies for weed control (vinegar solutions, etc.). Be aware that a lot of these ‘solutions’ could create more problems. Jan mentioned that using a vinegar solution could change the pH of your soil and make it harder for any plant to survive (not just your weeds). Commercial products (synthetic and organic) may be more expensive, but most of them have been tested for efficacy and will sometimes do a better job. If you have questions you can always check with your local garden center or university extension service.

Pests are always a problem in the garden and summer is their time to shine. Jan mentioned that aphids are at the top of nearly everyone’s list during the summer months. Aphids generally are not a huge problem, but in large enough numbers they can cause some growth problems for your plants. You can just hit them with a blast from your garden hose or look to apply some organic controls. A lot of people just leave them alone and let the ladybugs take care of them. Jan just squishes them with her fingers. One of the problems with aphids is the ‘honeydew’ from their droppings. This can land on leaves and create a black mold. This is not a problem with your plant, it’s just a result of their aphid ‘droppings’ on your plant.

They are followed by spider mites later in the drier parts of summer. They, too, can also be sprayed off if you do it regularly. Spittle bugs are also on the list. They are more of a nuisance and don’t do much damage to your plants. The foam ‘spit’ protects them from the sun and heat of summer. Just hose them off and, once on the ground, they will dry up or become food for a predator. Slugs are a pain for most gardeners in the Pacific Northwest. Many of us encounter them in the spring, but they can be a pest much of the year if conditions are right. Summer is the time to keep an eye out for them and treat if they become a problem. There are many types of organic and synthetic solutions, so be sure to pick the right one for your garden (phosphorus baits are good and safe, especially if you have kids or pets). If we have a huge rain or you are constantly watering your garden, you may need to reapply often.

I had a question next which dealt with mosquitoes. How can we control these buzzing pest from our evenings in the garden? The key is to eliminate standing water, which is where mosquitoes grow and breed. If you have a fountain, the movement of the water discourages them from breeding there. You can also add mosquito dunks to standing ponds and birdbaths. This is a product that is safe for wildlife, but prevents the larvae from forming and growing. Some people also say that certain plants can repel mosquitoes. These plants tend to be ones that have fragrant foliage or flowers. Scented geraniums, rosemary and marigolds are just a few of the plants that are rumored to work well. However, the best scent is obtained when the leaves are brushed or crushed, so you need to be close enough to the plants to brush them to release the scent. Jan said she needs to see more research before she could recommend that as a viable option. Speaking of small pests, we moved to ants. Ants can take many forms, from the smaller ants you see on your kitchen counters, to the larger winged varieties in your garden. Jan told us that some of the winged types of ants are just a natural progression when ant colonies get too big. The newer generation forms wings which allow them to fly off and establish colonies elsewhere. The key is to know what type of ant you are dealing with. They may be carpenter ants, but you would need to identify them before you treat for them. The same is true for termites. Capture a few and have then identified by an expert so you will know if they are a problem or not. OSU Extension has this publication to help you. Ryan then asked about box elder bugs. You have probably seen these little pests on the warm side of your house. The box elder bug is very active right now as it comes out and gets ready to mate. The box elder is relatively safe. They don’t eat the fabric on furniture, but they may stain items with their excrement. We recommend not spraying if you don’t have to. Pesticides will kill some of the beneficial insects along with the box elder bug. Instead, use a large vacuum to remove them or just sweep them off the house or move them outside if they are in your home. Be careful and use caution if you are going to use a ladder to reach bugs on your eaves. Don’t confuse these with the larger shield-looking Stink Bug. If you are not sure of the difference, stop by your local independent garden center.

We finished our discussion about summer garden pests with yellowjackets. If you mention the word "yellowjacket," most people will shudder! The image most of us have is of a nasty, mean, flying machine, that disrupts gardening activities and outdoor dinners. They attack even when they are not provoked and can ‘sting’ multiple times! Jan told us that these little beasts do serve a purpose: They are a beneficial bug! They can feed on other insects in your garden. Caterpillars and other soft bodied insects that eat your flowers and plants can be part of a wasp's meal. They may even do a little pollinating, too. Many times, a gardener will find them nesting in the ground and with just one unlucky step you can have a swarm attacking you. But you can also find them building small nests above ground too. The interesting thing we found out is that the colony will die off every fall and winter. In the fall a new queen is produced and she finds a place to winter over until spring. We have found them in our woodpile during the winter. In the spring the new queen wakes up and sets off to find a new home and start a new colony. The colony slowly builds and becomes larger, then will become more aggressive as the summer season wraps up. If a colony is far away, you shouldn’t need to worry, but if they are close to your home, you may want to remove them. To do that find a product that is specific to wasps as you don’t want to remove any beneficial (non-aggressive) bugs. Follow all directions for safe application. Most of the time the product will have you apply it to the nest at twilight when the wasps are returning to the nest. This will ensure that you get them all while they are in the nest for the night. For more information including the differences between Yellowjackets and Paper Wasps and how to get rid of them, check out this paper from OSU Extension.

After a quick break we returned to chat about diseases in the summer garden. Jan talked about the importance of knowing if you have a disease problem before you treat it. For some problems, there may be no solution, or the solution/treatment may have been earlier in the growth cycle. The example of blossom end rot on tomatoes came up. By the time you notice it, it is too late for a treatment. The prevention of this problem was during your planting of tomatoes. Adding a garden lime or calcium to the planting hole can help prevent those ugly black spots later in the season. The good news is that you can just cut off the end rot and the tomato can still be used. Jan recommended that you keep your plants as healthy as possible, which includes watering them well during the summer heat. Good watering will also help your other garden plants. When you notice your cucumbers curling or starting to taste bitter, that could be a sign of uneven watering. Keep them moist during the fruiting period to help prevent that.

Ryan then asked about some flowering cherries that he had seen. They looked great in the spring when they flowered, but now they have tiny little holes all over the leaves. Jan said that is "Shot Hole" disease. Once you see the holes, there is not much you can do. If you want to treat for it, you need to learn when to apply the treatment and in what amount so you don’t do further damage to pollinators or the tree. If you don’t have holes in your leaves but are noticing wilting leaves, especially on dogwoods, then you might have another problem. It could be anthracnose. First, confirm the problem and then treat. You can also help the plant by fertilizing it and watering well. If you do have problems with your trees, it would be worth the time and money to have a certified arborist take a look at your plants and recommend a course of action for treatment.

Judy then asked about roses. Roses are a favorite of the summer garden. The right varieties will continue to bloom all through the summer and into the fall. As with any rose, there are thorns. For us that means diseases and pests. The rose is the number one flowering plant in the United States and we talked about a few of the four problems gardeners face in the rose garden. We first talked about Black Spot. This is a problem that you will find in most rose gardens. It loves our cool, wet climate and attacks the young tissue on your roses. You have to start early in the season to prevent this problem. Now is too late to try and stop it but you can minimize it by taking the diseased material that falls off the plant and putting it in your garbage, not your compost pile. The spores from the diseased plants will stay in your compost and if you spread it around, could affect your other roses. We also talked about rust. This pathogen likes a range of dry-to-wet conditions. In the spring it will form when your plants get wet in the rain and then dry, and back and forth. Then we talked about the mildews, powdery and downy. Powdery mildew likes the warm weather. The fungus really likes these conditions and will thrive with overhead watering and lots of heat. Downy mildew is harder to diagnose. A lot of people think they have black spot when they really have downy mildew. It invades the leaf from the underside (think ‘down’ as ‘under’) and it can look like black spot. How do you prevent, or limit, these diseases? Good plant care is one way. Prune the plants to allow for airflow through the plant. This will allow the plant to dry quickly and make it difficult for spores and fungus to grow. Clean your pruners when you are working, especially if you are going from one plant to another. Try to minimize your overhead watering. Use a soaker hose instead. This will get the water to the plants and keep the foliage dry, preventing those disease problems. You can also look to replace your disease prone flowers with newer disease-resistant varieties.

We then switched to chatting about conifers and needle drop. Some people may notice that some of their conifers are starting to look a little dead. The inside of the tree may be filled with brown needles and dry foliage. This is nothing to be alarmed about. As your tree gets older it will shed some of the needles that are no longer being used. You should look at the tips of the plant. Check for new growth. If you don’t see any new growth or there are large patches of brown or branches that are entirely dead you should contact a certified arborist.

The summer can also be a time for planting. If you do plant in the summer heat, here is a technique for planting that reduces the transplant stress when you are moving plants in your garden. After you dig your hole and add amendments, but before you plant your new plant you should fill the hole with water. Then put your plant in the hole. This allows those roots and the entire root ball to get a good soaking. If you just planted the plant in the dry soil it increases the amount of shock the plant goes through. This helps take care of that. After letting the plant sit in the water for a few minutes, feel free to backfill the rest of the soil in the hole and finish by giving your plant one last drink to help settle the last soil you used. If you are planting on a very hot day, Jan also recommended that you plant in the early morning or later in the day to reduce the stress even more.

As we approached the end of our conversation we talked about a few more tips on watering, which reminded Jan about a problem that she thought was related to watering. She had a rose that was not responding to water and it was starting to wilt. She found out that voles had dug tunnels through the roots and so the water wasn’t getting to the roots at all. Sometimes you have to do a little digging to find the ‘root’ of the problem!

Another thing that you might notice in the garden are flower heads on your vegetables. This is known as bolting which is the plant going to seed. It has decided that the time is right to stop growing and time to spread seed. You can delay the seeding and get more from your plant if you snap off the seed head.

Finally, we talked about getting your fall crops growing by planting them in the mid- to late summer. We started with cole crops. A lot of people call them ‘COLD’ crops, but cole refers to plants in the Brassica family including broccoli, cauliflower, cabbages, kales and Brussel Sprouts. These can be planted in the ground during the warm days of late summer. They will love the late summer heat and because they can handle the colder soils and outdoor temperatures of fall and winter, they can be harvested when the rest of your garden is going to sleep for the season. If you have any questions about growing vegetables, please check out this great publication from Oregon State Extension called Growing Your Own; A Practical Guide to Gardening in Oregon.

The last thought from our crew is to encourage people to get out in their garden and enjoy all the hard work you have put into your plants. If you need any more information about gardening you can always check out the OSU Extension website.

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