Garden Questions of the Week

“After my hosta finish flowering, some of the leaves turn yellow.  What causes this?”  -Many factors can cause this including the fact that they just finished flowering and that takes a lot of plant energy to do that (so some leaves yellow), this time of year the heat gets turned up as well as the intensity of the sun, poor drainage or the lack of good even soil moisture, insects, and there is the ‘crown rot’ which could be an issue.

“The bottoms of my tomatoes have turned a brown to black color and are hard.  Is that a disease?  What do I spray it with?”  - Tomatoes are the number one vegetable grown in gardens and container gardens.  And this time of the year, although there are many tomato questions, this is one of the most common questions.  It’s called Blossom End Rot, a very common problem on tomatoes (but also happens on peppers, squash, melons, cucs, eggplant, etc), and can be the result of many factors:

-Water stress (uneven soil moisture available to the plant – when plants take up moisture from the soil, it goes to the foliage first, then to the fruits – lack of even moisture affects the fruit first.)  This also results in less calcium being carried to the fruit.  -Lack of calcium in the soil available for the plant to take up.  -Plants trying to get rooted in / established, producing new growth and fruit all the same time.  Root damages can cause this as well.  -High feedings of Nitrogen  -High salt levels in the soil  -Too low or too high pH   -Cold air and soil temperatures  -Soils high in salts   Again, this problem usually occurs early in the season (especially if wet spring, then dry ad fruit begins to set), and seems to taper off as the season progresses (plants become better rooted, etc.).  It is a physical problem, not a disease, so the ripened fruits can still be eaten (slice off the black spot) if desired. 

Controlling Blossom End Rot:  -Add calcium to the soil, using lime or gypsum, before planting the plants in the ground or containers (add to soil and till in).  These can also be added (top dress and light raking) once Blossom End Rot shows up on the fruit, to help correct future fruit from being affected.  (Water soluble lime, hydrated lime, very fine lime become available quickest of the lime – apply early.)  -Regulate your watering, so the plant is receiving good – even soil moisture at all times.  Increased timely waterings, as well as mulching tomatoes to retain soil moisture will help.  Proper watering and adding calcium are the two most important steps in controlling Blossom End Rot.  -Do not over feed the plants, especially with a high nitrogen fertilizer.  Excessive growth, stimulated by the high Nitrogen, increases foliage production, which increases the need for water and calcium to the leaves, and results in the lack of moisture and calcium to the fruits.  Use an all-purpose garden food, which is lower in N and higher in Potassium and phosphorus, as well as other needed nutrients, including Calcium.  –Check pH levels.

-Cold temperatures (soil and air) will also affect the flow of calcium / water to the plant and fruit.  Another good reason to not plant tomatoes too early in the season!  Plant when the temperatures get warmer. –Keep records as soon selections are more susceptible than others.  NOTE: Blossom End Rot may be more of a problem in containers – potting mixes do not contain calcium / harder to keep evenly moist.  Add calcium to the mix / use Soil Moist to help keep even moisture levels / water as needed.  The larger the pot, the less watering needed.  There are Blossom End Rot sprays, but are slow to be absorbed, it’s temporary, and you’re better of correcting the overall situation causing the problem.  Remember:  This very common tomato problem typically becomes less of a problem as the season progresses.  Do what we’ve recommended, be patient, and the Blossom End Rot should go away on your future fruits.  Then your tomatoes will be just right for the squirrels to take a bite out of them!

“I have been picking off the bagworms from my blue spruce, but now I see them in the top and can’t reach them.  Now what?”     -Well, you’ll need to spray them.  I love using Spinosad on bagworms – Bonide’s Captain Jacks Deadbug Brew.  All natural and really does the trick.  And you can find it in a hose end attachment that sprays to the top of the spruce!  (Sevin and Eight also work for bagworms).  May take 2 applications. 

“My yucca has finished flowering, and now there are what looks like seed pods on the stalks.  Should I let them go to seed?”  -I wouldn’t.  Most those seeds rarely germinate, and producing those seeds, along with having just produced their spectacular flowers, really takes a lot out of the yucca.  I suggest removing the flower stalk as soon as it finishes flowering, and let the yucca put the rest of its energy into being a better plant.

“My lilac has developed a white powdery like substance on the leaves.  What is it, and how do I get rid of it?”  -This is a very common problem on lilacs, and it’s called powdery mildew.  This usually shows up when the humidity goes up.  Fortunately for the lilacs, they can withstand the mildew without much harm.  On annuals and perennials, powdery mildew can be deathly.  You can’t cure it, but you can get it into check, by spraying with fungicides labeled for powdery mildew.  Or try using Rebecca Kolls’ home recipe for powdery mildew:  1 Tablespoon baking soda and 2 1/2 teaspoons horticultural oil dissolved in 1 gallon of water -spray all the leaves on the plant.

“Have you set the dates for the 2011 Nursery Outlet Sale yet?”  -Okay, just between you and me, we have!  We’ll be open to the public Sept 16-18 and 23 -25.  The official announcement will be coming soon, so don’t tell anybody! J

Garden Questions of the Week

“What do you recommend to get rid of tomato hornworms?”   -Are they tomato or tobacco hornworms?  Actually, it doesn’t matter, because control is best done by handpicking and destroying them.  Look for eaten leaves of fruit with their feces underneath the area.  You’ll find them, and then just pick them off.  If you absolutely have to spray (there usually aren’t very many on the plant), use Bt or Captain Jack’s Deadbug Brew.  By the way, they are the larvae of 2 types of sphinx moths.  If you want to identify which is which, the tobacco hornworm has 7 diagonal lines on its sides and a curved red horn.  The tomato hornworm has 8 – V shaped marks on its back, with a blue black straight horn.  Both feed on tomato plants and the fruit.  NOTE:  If you find them and they have white horn-like structures coming out of their backs, leave them alone.  That’s a parasitic wasp (eggs / larvae inside those structures) feeding on the hornworm, and will kill it shortly.  By allowing them to mature, they will help you control hornworms ‘naturally’!

“Is this the time of the year for yearly locust? I started hearing them today.”  -Yes, annual cicadas are emerging now, and those sounds are from the male cicadas.  With annual (or dog day) cicadas, also keep on the lookout for cicada killer wasps.  Not aggressive, but very big and drill holes in the fronts of landscape beds or in soil easily worked (female drills hole, deposits egg, catches a cicada, stings it and places it in the hole for the larvae to feed on).  They can sting, but again, not aggressive, so just stay out of their way and let them take care of the cicadas for you!

“I’m seeing Endless Summer Hydrangeas with both pink and blue flowers.  Why is that, and how do I get mine to stay blue?”  -The color of the hydrangea flower depends on the pH of the soil and the availability of aluminum.  With lower pH, the natural aluminum in the soil becomes more available to the hydrangea, which is what makes the flowers turn blue.  A more alkaline soil ties up the aluminum, making it not available, and the flowers stay pink.  So your goal is to create an acidic soil around your hydrangea.  You can do this by adding Pine Soil Conditioner when you first plant, as well as using it as mulch.  This helps to lower the pH.  Adding coffee grounds around the plant helps lower pH, and, by adding aluminum sulfate in the spring and fall to the soil around the plant, you’ll also be lowering the pH, as well as adding aluminum to the soil – all helping to get those flowers to turn blue.  And if you get it just right, you’ll have both colors!

“When I prune the dying flower heads off my Endless Summer Hydrangea, do I prune them off at the next leaf node or all the way to the ground?”  -Prune above the next or next lower leaf node.  Pretty much the same with all the hydrangeas, deadheading just below the spent flower on lower leaf node.

“I’m confused.  My hibiscus isn’t the same as my neighbor’s hibiscus.  How many types are there?”  -Good question!  In our area, we’ll mainly see 3 types of hibiscus being grown.  There is the very hardy woody shrub hibiscus, also known as Rose of Sharon.  Comes in a variety of colors, single and double flowers, and is a large growing woody shrub that flowers from mid-summer until fall.  Another is the hardy perennial hibiscus.  These bold perennials come in a variety of colors; some with dinner plate sized flowers, and make a great summer show in the perennial garden (they’re cut back close to the ground every spring).  And then there’s the tropical hibiscus, which is not hardy here, and must be taken indoors over the winter.  Again, a multitude of summer colors, but is a tropical plant.

“I have some strange looking substance growing on top of our mulch!  It has gone from yellow to brown and looks foamy.  What is that?”  – Give me the right moisture levels, humidity levels and some organic matter breaking down, and I’ll show you some pretty funky looking things growing in the mulch.  Whenever organic matter breaks down or is decomposing, you have bacteria and fungus helping out.  You don’t see the bacteria, but the fungus can show up in many ways, including mushrooms. But there are a couple different things you’ll find in the mulch besides mushrooms.  Birds Nest Fungus is one, and if you look closely, the fungus actually looks like a cup or birds nest, and looking even closer, you’ll see the ‘eggs’ in the middle.  The fungus spores are actually in the ‘eggs’.  When a rain drop lands in the nest, it forces the spores to jump out and land somewhere else in the mulch, to start the process all over again.  You’ll also find what you’re describing.  It’s called Dog Barf or Dog Vomit Fungus.  Shows up over night, and looks like someone, or the dog, threw up in the mulch.  This actually is not a fungus, but a slime mold, again developing as the mulch decomposes, and can slime its way up on foundations and plants.  It starts out yellow or orange and slimy, then begins to dry, turns beige to brown and gets crusty on top – which eventually cracks open, and the spores fly away with the wind and the process starts all over again.  Neither one of these are harmful to pets, kids or plants – they just look weird in the mulch – and there’s no control besides fluffing up the mulch, or scooping them up and throwing them away. 

Reader Comments: “Just wanted to share my way of protecting my tomatoes from insects and critters.  I have two container plants scooted close to each other, with a stake on the outside of each pot and a tomato cage over the plant.  I then secure a netting of ‘chiffon’       over and around the plants, using the stakes and cages as support and twist-ties to pull it tight and secure.  I can water thru the netting material, the plants grow great (plenty of sunlight), and I simply un-twist a twist-tie, open it up, and take out my ripe tomatoes.  Works great!  -Fran V.   (‘Grow covers’ would work, too!  Thanks for the tip! J)

Garden Questions of the Week

“What is that blue flower I see every summer growing along the road?  I want it in my garden!”  – That wonderful blue flower belongs to the perennial herb ‘Chicory’.  Yes, the same Chicory you’ve heard about as an additive to mellow the flavor of coffee (brought here by the Europeans).  The foliage is similar to dandelions, which by the way was once eaten fresh or cooked.  And the roots were harvested, roasted and brewed as a drink or added to coffees.  But it’s the wonderful soft powdery blue flower that gets your attention.  All born on the long somewhat foliage-less stems, they’re at their best early in the morning sun.   These plants will flower pretty much all summer, with each flower lasting only a day or so.  So can Chicory be grown in your garden?  Yes, and the best way is from seed, planted in the spring, not by trying to dig them up and transplanting them. 

“How do you feel about grass growing under trees?  We have new trees and can’t decide whether to let the grass grow or mulch around the trees.  What do you suggest?”   -No brainer here for me!  No grass.  I feel that newly planted trees / evergreens should have a minimum 3-4’ diameter circle of mulch around them from the start (no matter how small the tree) and should be enlarged annually as the trees continue to grow.  Grass can be a fierce competitor with trees for water and nutrients.  Especially if they’re fruit bearing trees!  Research has shown time and time again that newly planted trees without grass growing around the trunks perform better and grow faster than those with grass immediately around the trunk.  And, these mulched areas help prevent lawn mower / string trimmer blight, which is caused by the mowers bumping the trunks, or string trimmers wearing down the bark.  Remember, mulch 1-3 inches deep, and never place the mulch against the trunks of the trees. 

“We purchased a Crusader Hawthorn tree last year.  It seems to have lots of growths\bumps all over the green fruit berries & when touched they crush to an orange powder.  I’ve been trying to search online & think it might be hawthorn rust.  It doesn’t seem to be on the leaves.  We have lost leaves as well.   I don’t really see much treatment listed.  I just am questioning how to know it’s rust & if I need to do anything to treat it this year or next spring.”  -Rust can be somewhat common especially when the weather conditions are right.  Nothing you can do at this stage besides collect leaves and fruit that drops and pitch it out.  You can spray as a preventative next spring starting at bud break repeating 3-4 times based on the label -use Sulfur, Mancozeb or Bonide’s Fungonil.  Take samples to local garden store for someone to see and possibly identify.  But what you’re describing sounds like one of the rusts. 

“I know Knock Out roses are low maintenance, but is there anything I should be doing to them during the growing season?  I’m also getting holes in the leaves.  Should I spray something?”  – Even thought they’re basically a low maintenance rose, there are always a few questions on taking care of them, like how often should they be fed, do they need to be deadheaded, and in some cases, what’s causing the small holes in the leaves?  Knock Out roses are somewhat self deadheading, and you do not have to deadhead the spent flowers, but it does help to speed up the re-flowering process and increase flowers.  You can see where the spent flower stems start to lose color and the new growth starts coming out below that.  By clipping that spent flower (flower cluster) out earlier, we can speed up the process.  Again, you don’t have to, but it does help.   And if a branch grows faster than the rest of the plant, feel free to clip it back during the season to give the rose bush a more even look.  When it comes to feeding, this rose gets by on light feedings, but for optimum re-growth and flowering, feed once every 4-6 weeks with a rose food (Espoma Rose Tone) – stop feeding around mid to late August.  And as for these small holes in the leaves; they’re from a very hard to see leaf eating caterpillar like critter called ‘rose slug’.  It’s not a slug, but actually a saw fly larvae.  They’re lime green, look just like the veins on the leaves, and feed on the undersides of the foliage.  Systemic insecticides (Bayer and Bonide) applied around the root system in mid spring helps to control rose slugs, as well as foliar sprays of insecticidal soaps or horticultural oils.  Remember to spray the undersides of the leaves, rather than the tops.  Now if you haven’t applied a systemic earlier, you still can, as there are multiple generations of the rose slug.  And even if you did nothing at all, those Knock Out roses leaves will look bad, but they take the lickin’ and keep on tickin’ with colorful flowers, all season long – in most cases until late fall.

“My azalea leaves look washed out.  I don’t see anything on them.  Any ideas?”   -The answer to this situation lies on the back or undersides of the leaves.  Its azalea lace bug -you can see where they live as well as those black spots – that’s their excrement.  Starting in spring, usually around the time flowering is finished, the lace bug eggs hatch and both adult and nymph lace bugs pierce the leaf’s underside and suck the juices from the plant.  That’s why the leaves become chlorotic looking, lose their color, and many times drop off early.  Good thing is, azaleas can withstand quite a hit from lace bug and continue to grow and flower.  But it is best try and control lace bug damages and minimize the stress on the plant.  Try to catch them early in the season – watch for them right after flowering.  Spraying the undersides of the leaves with insecticidal soap or horticultural oil does a nice job, but may need repeated applications every 3-4 weeks, as there are multiple generations.  And remember, spray the undersides.  You can also help from the inside of the plant by applying a systemic insecticide as a soil drench early in the spring.  A combination of the two usually helps keep azalea lace bug in check.  And remember good cultural practices – feed as needed in the spring, and water as needed thru the summer.  A healthy azalea is a great defense against lace bug infestations.