The Approach Graft

Seeing as this blog is called “The Garden Professors” it has been far too long since we’ve given you a lecture on a useful practice for your garden, so this week I thought I’d give you a little how-to demonstration on something called approach grafting.  Approach grafting is a technique that you could use to graft a tomato to a tomato (good if you want to use a disease resistant root with a non-disease resistant top — common in heirloom tomatoes), a tomato stem to a potato root (just a fun project), or an eggplant root to a tomato shoot (good for wet locations).

So here we go.  First, you need two plants that are about the same size, and you need to plant them in the same container as demonstrated below with a potato and tomato.  You will also need to strip off lower leaves as they may get in the way of the graft.


Above we have a young potato and tomato plant to be grafted.


In the above picture the potato and tomato plant have been planted in the same container and their lower leaves have been stripped off.

After the two plants are in the same container a small slice is made on each plant at the same height.  This slice will be, ideally, just a little bit deeper than the cambium into the center of the stem (you’ll be able to see the plants pith — in the center of the cut — it’s tough to see in the image here).


In the above picture the stem of both the tomato and potato are cut so that they can be joined together.

After making the required cuts on both plants the cuts are pushed together and wrapped.  We used parafilm to wrap this graft, but saranwrap, or even an elastic band would also work.


In the above picture the cuts are being joined.


Here the cuts are wrapped.

The next step is to wait until the graft “takes”.  This could take 3-5 weeks.  After a good strong union is formed the top of the potato and the bottom of the tomato plants are cut off.  Wait a few days to make sure everything’s working properly and plant the result in your garden.

Veggie garden safety

A few months ago I posted a caution about using old pressure-treated timbers for vegetable gardens (see my Sept. 23 posting).  I now routinely get questions about alternatives to these arsenic-laden materials, especially new treated lumber.  What’s in the new wood that makes it rot resistant, and is it dangerous?

Rather than arsenic, new pressure-treated lumber has copper as its active ingredient.  Though it also will leach out of the wood, there is not a human health hazard associated with its uptake by plants or animals.  You probably get more copper leaching into the water carried through your plumbing (assuming you have copper, and not lead, pipes).

What about plastic timbers?  Though I’ve not seen any literature about leachates from plastic lumber, I’ve seen some older plastic timbers that haven’t aged well – they can warp and twist.  I would avoid those made of rubber, because decomposing rubber produces leachates that are quite hazardous (see September 30 for a discussion on rubber mulches).

Of course, there are many other materials one could use to corral their veggies – concrete blocks, stone, natural wood, etc.  Do you have a favorite?  Post a comment to let us know!

Veggie gardening science – whaddya know?

I just had a long conversation with Michele Owens (of Garden Rant fame) about vegetable gardening.  This isn’t one of my strong areas, either professionally or personally (I do have containers of herbs, but that’s as far as it goes).  But what piqued my curiosity was her revelation that the vegetable gardening is just as full of myths and misinformation as my field of ornamental landscaping.

I’ve ventured into the realm of vegetable garden science now and then, especially in reference to having soil tests done before planting edibles (good!), the use of CCA-treated timbers (bad!), and companion planting (silly!).  Beyond that I haven’t given the topic much thought.

          

(You know who loves you know who!)

So, readers, what gardening practices out there need to be screened through the sieve of science?  Jeff and I have both written about many practices and products, but as you know our expertise is more on the ornamental side.

(Forgive my short blog today.  I’ve had some kind of chest crud since last Friday and I’m still wiped out.)

Eat your veggies! (But not the arsenic, or the chromium, or the lead…)

vegetables_jpg.jpgThe last few years have been a perfect storm for the resurgence of home vegetable (and fruit) gardens.  Grapevines are trellised along sidewalks, herbs replace the grass in parking strips, and tiny gardens of carrots and lettuce are shoehorned into any available spot.  It’s all good  – but we need to be particularly careful about what those plant roots might be taking up along with nutrients and water.

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1)  Contaminated soil.  Many urban (and suburban, and even rural) soils are contaminated with heavy metals, pesticides, and/or industrial wastes.  Lead is commonly found in soils near roads (from the old leaded gasoline we used to use) or from old lead-based paint chipping away from houses.   Arsenic is a very real problem in North Tacoma soils, for instance, thanks to the smelter that operated there for decades.   Overuse and incorrect use of home pesticides will leave residues in the soil for years.

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2)  Contaminated compost and soil mixes.  Many of the same contaminants mentioned above can be found in unregulated composts and soil mixes.  (More on this topic here.)

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3)  Treated lumber.  The old treated lumber (CCA = copper, chromium and arsenic) is no longer being sold, but it’s out there.  These timbers should not be used around vegetable gardens, as they will leach their heavy metals into the soil.  Vegetables vary in their ability to take up and store these metals.  (More on this topic here.)  Likewise, rubber mulches may leach unwanted chemicals into the soil and should not be used around food plants.  (More on this topic here.)

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What can you do to avoid these problems?  A few things are quick, easy and cheap:

1)  Have your soils tested.  I’ve mentioned this in an earlier blog on urban soils.  It’s the best way to find out exactly what you have in your gardens – the good and the bad.

2)  Use only certified composts and soil mixes.

3)  Plant in containers if your soils aren’t safe for food.  This is especially easy to do with perennial herbs, which can be kept like any other container plant on your deck or porch for years.

4)  You can also replace the soil in your vegetable garden.  This isn’t quick, easy, or cheap, but is a solution for some people.