Archive for spring garden prep

Safe Soil in the City

Portland landscape designer Carol Lindsay

Daizzie and I in my edibles garden

Safe soil in the city – smart and healthy practices for urban gardens

I love having a vegetable garden. It’s healthy, right? I love eating kale and I grow a lot of greens for smoothies year-round.  There are a few concerns about growing food in urban areas. Two concerns that apply to us all, city and suburban, are lead paint and lead exhaust from the past in our soils. Let’s be practical not scary about this.

Is my food safe to eat? What are the most important practices I can do and how can I keep it simple?  My garden is below Highway 30.  It’s an old heavily traveled highway so our soil has years of exposure to lead exhaust.

There’s no way I’d grow my food in the ground here.

My current garden practices

I’ve been assuming my food is safe to eat because:

Our community garden has raised beds with new clean soil from just three years ago.
I apply lots of compost at least three times a year.

Carol's winter kale

My garden supplies me with year round greens like kale.

I use an organic fertilizer. (OK it’s boxed Dr. Earth, not a truckload from Natures Needs because it’s very convenient and my garden is small.)  I don’t know what my NPK ratio is which makes me a bit of a lazy gardener but the food I like to grow does fine.  NPK being Nitrogen, Potassium, Phosphorous.  And yes I was trained as an advanced master gardener and yes that was a very long time ago………they teach you all about soil in the master gardener program.

I wash my produce, no nibbling right out of the garden bed. (OK once in a while a strawberry or tomato).

According to some experts I’m doing OK but I could do a lot better.

My improvements

  1. Soil areas next to old garages often have higher lead levels.

    Soil areas next to old garages often have higher lead levels.

    Reducing exposure to dust is the most effective thing you can do to reduce lead hazard in your landscape. It is typically in the first few inches of soil. This is the most important thing in the blog.  Mulch and compost applications cover your soil and protect it from dust with contaminants in it.    We want to keep the dust and soil off human skin and out of the mouth.  This is critical for babies and small children and good for the rest of us too.  Adding compost has many benefits for improving conditions for plants.  Adding compost at least twice a year can only benefit, there are no drawbacks.

  1. Here at my community garden, we could have put a barrier between our new soil and the existing ground soil. I can still do this once my winter Kale are done in March. I’ll have to get a tarp and dig out a lot of my soil so I’m going to install a metal grid and landscape fabric.  The grid is to keep the moles and gophers out of my raised bed. They may have brought some of the lead contaminated soil up into my new clean soil, and they caused a lot of havoc with the roots of my plants.  Some died or did not produce well because of the soil disturbance.
  1. I could improve the efficacy of washing my veggies by using a 1 percent vinegar solution instead of only using water. I’m thinking a large spray bottle under the sink could be used for my final wash. It’s got to be simple or I won’t do it.

Beyond these good soil management practices, I will need to do a Nutrient Analysis soil test to know what I need to add to my raised beds to improve the health and productivity of my vegetables and bind up any lead and keep it locked into my soil where it won’t cause problems for me.

Portland landscape designer in edibles garden

My garden is below Highway 30. It’s an old heavily traveled highway so our soil has years of exposure to lead exhaust.

Lead Soil Test

My client Katy had an older home in SE Portland.  I suggested a lead soil test.  She collected the soil and submitted samples for a lead test. She discovered the area where we wanted the kids play structure to go had high lead.  It was next to the neighbors’ garage.  Several inches of contaminated soil were removed.  She brought in new soil and playground chips and now has a safe play area for her toddlers.

What’s one new thing you could do this year to improve your landscape or edibles garden?  Get your soil tested.  I’m planning to collect soil from my vegetable garden and submit it to a lab for testing.  I’ll share that experience with you in another blog.

Lace Bug Update

Azalea Lace Bug damageLast year I wrote a blog about a serious new insect problem for landscapes in the Pacific Northwest. It was serious because rhododendrons and azaleas make up a large percentage of the plants in most gardeners landscape. The easy way to control the insect was with a systemic pesticide that harms bees.  Many people were talking about removing all their susceptible plants rather than harm bees.

Here’s my latest report and what you can do to save your plants without killing bees:

Save bees and your azaleas and rhododendrons. How big a problem?
I have visited over thirty client landscapes in the Portland area since February – all the gardens but two had moderate to severe lace bug damage on rhodies and azaleas.  I was already expecting the 2015 lace bug plant damage to be a huge problem for my clients. Robin Rosetta, Associate Professor, Extension Entomologist, OSU says the lace bug hatch is a full month early.  This is very bad news unless you are prepared to start treating your plants now in mid-to-late April and early May.

Lace bug eggs waiting to hatch.  Photo by Robin Rosetta.

Lace bug eggs waiting to hatch. Photo by Robin Rosetta.

Strong blasts of water should be applied to the back of the leaves to damage the wings of the lace bug while it is in its soft nymph stage.  It can be a little difficult to hold your leaves steady to spray the back side, especially if it is a large rhododendron.  Portland Nursery has something called a Bug Blaster Head for your hose.  It’s easier to use and has a safer pressure for your plants’ leaves.  It also has a wand attachment that would make it possible to treat a large rhododendron.

Insecticidal soaps applied to the back of the leaves will also damage the lace bug nymph. These two methods are effective only while the nymph is soft.  Once it turns into an adult, soaps won’t work and water spray will not remove embedded eggs.

Green-Lacewing March Biological

Green-Lacewing March Biological

This may get confusing because the bad bugs that damage your plants are called lace bugs.  I’m about to introduce you to a good bug that eats the bad bug. The good bugs are called green lace wings.  If you don’t want to spray your plants because they are too big, there are too many plants or you want to work toward a long term solution; you need to purchase green lace wing larvae from March Biological  or go to Portland Nursery to order through them.  The green lace wing will eat the newly hatched lace bug and prevent the lace bug population from exploding.  Getting green lace wings in a high population in your garden will help with the next one or two lace bug hatchings that we expect this year.  My friend, Phil Thornburg, from Winterbloom has successfully diminished his damaging lace bug population. It took him a couple of years but he did it by applying green lace wings instead of pesticides.

Plants in full sun seem to be the most damaged from lace bug.
Basically they are stealing the green right out of the plants’ leaves and laying eggs that will hatch in another month adding insult to your already damaged plant.  Remember to water your rhododendron and azaleas regularly this summer –  they will need the extra support.

Question: What does lace bug on my rhododendrons have to do with bee colony collapse disorder?

Rhody Lutea March 2015 treated with bee killing spray

Rhododendron ‘Lutea’ in my client’s garden without any damage.  A rare occurrence.

Answer:  Systemic drenches often contain imidacloprid. It’s popular because it’s easy, the chemical is suppose to be safer for mammals (so humans, rats, bats are pretty safe) but the spray will harm or kill bees or any insects who feed on the plant.  For months afterwards bees take it back to the hive with the pollen so it’s not just harming one bee – it’s harming the colony.

The time to treat your plants without harming the bees is now!

 

Hydrangea Pruning Made Simple

Spring Hydrangea Pruning

A lot of my clients have asked me to help them with pruning their hydrangeas.

Hydrangea serrata 'Preziosa'

This blog addresses mophead hydrangea pruning.  Hydrangea pruning is simple and easy once you know the rules.  There is a link to a pruning video at the end of this blog produced by Cass Turnball of Plant Amnesty to help you feel more confident.  There are 5 kinds of hydrangeas.  This blog only addresses mophead hydrangea pruning.

 

Hydrangea serrata 'Preziosa'

Why prune hydrangea at all?

Why prune hydrangea plants at all?  Like most plants, pruned hydrangea shrubs will have a better shape so they look good regardless of the flowering aspect.  Many of us buy a hydrangea and think it will be 4’ x 4’.  Over time, many varieties will grow to 7’ tall.  It is very important to plant the right plant in the right place so you don’t have to be frustrated.  There are some varieties that are going to mature at and be easily kept in the 4’ to 5’ range.  We prune to achieve that height as well as a good shape.  If you have a variety that wants to be 7 or even 8 feet tall every year even with proper pruning, the best answer is to remove the plant and buy a variety whose size works for your garden.  Old Arts and Crafts homes with 6’ high foundations are perfect for the hydrangeas that are most cheerful at 7’.  They don’t work as well for homes with a 12” foundation or a small yard.Another reason we prune is to remove stems that no longer flower.

rabbit ears 2

Nicely pruned and open plant

We prune hydrangeas in early to mid March in the Pacific NW.  We start pruning our plants when they are about 3 years old or when you see the oldest stems are developing bark.  Remove the oldest woody canes.  On a young plant this might mean removing only 1 or 2 stems.  We remove dead stems and canes and we deadhead flowers back to the first lateral buds.  I think of these buds as rabbit ears.  I love this task.  I think it’s because I’m close to the ground and my soil smells good.  I typically see 2 colors of buds at this time.  The burgundy buds are just a bump on the stems.  The tiny green buds (the rabbit ears) are such a vivid green.  It says spring to me (and no it doesn’t rain every minute even in March).  These are days when a wool sweater and a down vest are perfect for comfort.

hydrangea 1 heads banner

Joy Creek Nursery Hydrangea Garden

There is more to the story about hydrangea pruning. Occasionally there are individual plants that didn’t read the rule book.  My garden coach client Mary followed the proper pruning techniques and she lost all her flowers for the year!!  AAACK!!  Her plants are 30 plus years old.  Since that debacle Mary only deadheads her plants, again just down to the first buds and she removes old woody stems.  Her plants always flower beautifully and are the focal point of her summer garden.  I’ve never had this happen to me but I’ve heard about it often enough from other professionals to know that some plants are probably genetically different than others.  If you don’t prune at all, your plants will get big and ungainly looking.  A build up of deadwood may diminish their flowering capacity.

For a detailed lesson on pruning mop head hydrangeas, see this video.

Garden Tips: Top 5 Spring Garden Prep Tips

Evergreen Orange Sedge

Groom Evergreen Orange Sedge grass but DON'T cut them back

Here are my Top 5 spring garden prep tips or things to do now or in early March:

  1. Cut back deciduous (gets dead looking in winter) grasses to 2″ tall stubble. Don’t cut back evergreen grasses-they grow back too slowly and will look ugly for a full year.
  2. Scrub your flagstones, especially in the odd corners where they have become very slick. Same for concrete, where you don’t typically walk, it can be very slippery. Bleach will harm your stepables and if you track bleach in on your carpet, it will be a sad thing.  Some do use a 1 to 10 water and ammonia on their flagstone with steppables.  (10 is the water, 1 is the ammonia okay?)
  3. Cut back Lavender to the lowest bits of new growth. Do this now or before mid March. We are running out of time for best results.
  4. Trim a bit of Rosemary and make some good chicken soup. The flu season has me making a lot of soup. We have had our patience sorely tested waiting to get over this years flu. (2011) Rosemary is both fragrant and flavorful. It lifts my spirits just picking it, I also like it with eggs and potatoes for breakfast, so simple, so good and so easy to step outside my door and snip.
  5. Time to start thinking about an inch or two of compost for as soon as you finish spring clean up or April 15 which ever arrives first.