plant diagnostics (how to grow a green thumb)

I love the popularity of gardening right now and it breaks my heart when I get emails from people who feel defeated or overwhelmed at the process of getting a seed the size of a comma to grow into a snack for their kid. Seems like there are many of you who want to garden and feel like you have bad luck. I know that feeling, the supreme disappointment in dedicating so much time to nurturing something and ending up with a failed crop. It happens to everyone. Don't throw in the gardening gloves just yet.

Here's a secret: Green thumbs aren't genetic, they're learned. I don't believe in bad luck. You've got this.

In our small backyard plot: garlic, cauliflower, carrots, kohlrabi, bush beans, parsnip, tomato, cucumber, pea, lettuce. Strawberries and raspberries not in view. The bed on far right is the beginnings of a late planting of arugula and chard.

I am going to talk specifically about diagnosing problems but feel compelled to mention that there are things that should happen first to reduce problems. Just like humans, healthy plants with proper care are stronger and more productive. Pick good placement, rotate crops every planting (a good rule: leaf, root, fruit), test soil, learn what grows well in your climate and what grows well next to each other (companion planting). Practice prevention by keeping plants healthy and strong. Learn about watering timing and technique, weed, prune correctly, remove and destroy diseased plants etc. I list a few books at the end of this post that can help you with all of this.

OK, back to the problems. I get a lot of questions that go something like "Something is eating my tomatoes. What can I do to fix it?" and that question is like asking a doc, "I feel off. Can you prescribe something?" Thing is, a diagnosis has to happen to help the problem. I don't know much when I see sad broccoli but I can figure it out and fix it. It is very empowering. You can too. It's a snap, a matter of learning a process and using tools that are free and easy. I'll show you.

I use organic gardening methods. It is really important to me to use the least toxic, least harmful spray. A diverse insect population and healthy soil microbial activity are the key to sustainable gardening and healthy food.

I am using two real examples from my garden this year:

ONE: Cauliflower

little cauliflower heads just this week!

TWO: The entire left half of my front bed (spinach, squash, beets).

Photo taken June 13

  • Identify the plant that has the issue. Different bugs like different plants; different plants host different bugs. You need to know the plant with the issue before you figure out which bug or virus or whathaveyou is affecting the plant. My plants with the issues:

    • Cauliflower
    • Spinach, squash and beets (all in one bed with similar symptoms).

  • Study the plants and record the symptoms.You get to play doctor, beginning with taking a look. Is the problem with the leaves? Stem? Fruit? Roots? Is there yellowing? Holes? Brown spots? Write down what you see and take a photo to reference.
    • Cauliflower: I see small and large holes on the leaves of my plants. Color looks good and growth isn't affected. 
    • Spinach, squash and beets: small growth, stunted plants. The older leaves are yellow, the newer leaves are green but puny. 
  • Look up the plants in a plant diagnostic tool. I have my master gardening manual that I reference a lot (I highly recommend this class to anyone who wants to learn more about growing plants). I also love my local Missoula County Extension Office Plant Diagnostics Database that is online and I check in there all the time (click on links below on the different veggies to read what I read in that database).
      • Cauliflower: I quickly learned that it was either Cabbage Worms or Cabbage Loopers.
      • Spinach, squash and beets: This was trickier as it was still early in the season. Since those three plants don't have many insects that would feed on all of them (remember, not all bugs like the same plants), I decided it wasn't a bug and maybe a fungus or virus. But again, I read through all the possible symptoms and nothing really matched my problem. Yellowing on older leaves can mean a nitrogen deficiency so I decided to start there.
    • Create and implement a plan to address the problem. Again, different things kill different bugs and different fertilizers have different effects. Spraying insecticidal soap doesn't kill cabbage loppers so spraying it would do nothing. And applying a general fertilizer won't give me enough nitrogen so using it would be futile. You have to use the right tools. 
        • Cauliflower: I went back out to my plants and started searching for bugs. It's hard because the dudes blend in really well. Every time I am diagnosing a bug I have to stare at the same leaf for a while and then the critter will snap into focus. Once I see one, others are easier to find. I found a green worm and wasn't sure which it was so I watched him and he didn't move at all and had a faint yellow stripe. Cabbage Worm it was. Also, look at this page and see what other plants host this bug. Thankfully, none of those plants are near my cauliflower so these worms are only on the cauliflower and no risk to the neighboring tomatoes, parsnips and beans. However, my kohlrabi isn't far away so now I know to keep my eye on the kohlrabi. BUT THEN! I found a different looking green bug. One that moved quickly and had lots of babies. I had Cabbage Loopers too. I read about them in the book and online database. I could spray BT but because I am only dealing with six plants, I decided to scrutinize every nook and squish every looper and worm I could find. Also, I watered with an intense spray to knock of any stragglers. I applied a general fertilizer to give the plants a boost. I learned that the eggs and larvae are fed upon by birds and insects so I am happy I have a healthy ecosystem in my plot with lots of bugs and birds to help me keep this in check.
        • Spinach, squash and beets: I read about good sources of immediately available nitrogen. By "immediately available" I meant that nitrogen would release quickly instead of slowly, over the course of weeks. I decided on blood meal. So I bought some from my local nursery and followed the directions for application.
        Photobucket same squash plants on June 26 and July 7

        That's it! Then you wait and see if it works. And, if it doesn't or something else pops up, start over at step two. Both of my diagnoses were correct.

        Front bed on July 9. My favorite part is the hippie strolling down my sidewalk playing the banjo. Maybe it had nothing to do with the bone meal and everything to do with stringed instruments?

        I continue to check the cauliflower and kohlrabi for worms and loopers. I pulled one particularly sad cauliflower plant and fed it to my chickens. The squash and beets greened right up and started to grow and set fruit. But my spinach never did well. I think it is because the plants were stunted when the weather was just right. Once they had the nitrogen they needed, it got hot so they leafed out and bolted. Bummer.

        looking mighty fine, kohlrabi

        :: RESOURCES & TOOLS ::

        My two favorite gardening books:
         The Vegetable Gardener's Bible
        and The Gardener's A-Z Guide to Growing Organic Food.


        They regularly come with me into the garden as evidenced by the water damage and dirt. The latter is new to our library, a copy sent my way for review this year. And, since I am now listing it in my top two favorite gardening books, you can glean that I like it a lot. The book is simply organized and contains so much information. It is a beautiful, accessible encyclopedia that gives me everything I'd want to know about what I have growing in my yard. There is also a juicy, informative section titled organic remedies that outlines best practices and troubleshooting tips. It's a great book.

        bush bean forest

        A few insecticides I have on hand that work really well for some bugs: insecticidal soapneem oil and pyrethrin. Purchase these after you have determined what is eating your plant and then read the labels to see if these will help your hungry bugs. I also have a pump sprayer for easy application.

        Things happen all season.  I feel like I kind of know what I am doing and I still struggle with crummy crops every year. Last year I harvested a puny pile of potatoes because of blight. The year before that I couldn't recover my spinach from a leaf miner explosion. But most of the time, I can fix it! Especially if it is caught early. I know it is tempting to pull your pathetic carrots and make yourself a cocktail but try instead to figure out what's wrong and take a stab at fixing it. And then make yourself a cocktail in celebration. I think you'll be surprised at how green your thumb is.

        How is your garden growing? If you have a question, I'll do my best to help out here in the comments. Or, post your question over at the Virgin Harvest page and get a thread going! 

        :: :: ::
        all photos taken with a Canon Digital SLR from Vanns.com


        PapillionMom said...

        Awesome post! I am in my 5th year of gardening here in Nebraska (never did it in California) and I love it. But like you, I struggle with the occasional blight, odd bugs and failed crops. This year we're working on pumpkins, green beans, several types of tomatoes, peppers, jalapenos, cucumbers and watermelon. So far so good, though I am worried about a couple of my tomato plants...lots of bush but no bloom :-/

        Katie said...

        Excellent points in this post, and those are two GREAT books that simplify things and give a great foundation! They were both among the first gardening books I purchased (and still use).

        booksNyarn said...

        I am in my second year with my raised beds, and there is definitely something eating at my kale. The broccoli looks good but isn't setting up heads, but it is my first year with them. I am going to do soil testing and prepare the beds for next year. Thanks for the tips and the resources (more books, yay!).

        Courtney said...

        Excellent post! Thanks Nici. I've found the county extension agent to be invaluable.

        Now teach us/ me how to prune tomatoes? I'm scared...

        ~ M ~ said...

        Wow! That squash was an amazing rebound! I was late getting my veggie plants in this year & only managed to put a few in about a week ago. Spokane had a wet cold spring and I kept procrastinating. Just hope my stuff gets some grow on!

        Kelly Cach said...

        So helpful....thank you! Do you grow flowers, too?

        What do you think about cat poop??? I hate cat poop. I like cats, but my youngest son and I are terribly allergic, so we are not cat owners. There are currently 3 cats in the neighborhood that use our yard as a litter box...seriously sooooo frustrating! So stinky and my kids are forever saying, "MOM....I STEPPED IN CAT POOP AGAIN!" I've tried (and spent a lot of money on) MANY harmless concoctions to deter them, but to no avail. Do you have any suggestions for keeping the cats out?

        I DO have to say though, that my youngest son won the Sweepstakes Award for his Zinnias this year at the fair. And guess where they were planted? In the most cat poop infested pile of dirt in our yard! Hahaha! Is there a connection? And now this year we have either flourishing squash or pumpkins growing in the same area!

        Anyway, sorry for the long-winded message. It's just been a very long 6 years of smelling, scooping, & stepping in cat poop.


        www.preparingforthebaby.com said...

        Thanks for the tips! I was totally nodding at the part where you said it took you some time just staring at the plant to find the pest. I find myself having the same issue. Fortunately we haven't had many pests.

        The thing I would recommend to interested gardners is to just go for it. We live in a beach community, so our backyard is tiny. Nevertheless, we squeezed in a garden that is producing yellow squash, cucumbers, corn, blackberries, strawberries, carrots, pumpkin, beans, red bells, onions, thyme, basil, rosemary, parsley, and oregano. It can be done!

        Also, we don't grow anything illegal (I think they are typically used for growing pot), but "smart pots" are fabulous for growing stuff in contained areas. We were given a few and they work great...we grow our basil in them.

        Ellie said...

        I'm teaching Writing to high school freshmen in the fall, and I'm thinking this would make for a great example of a "Process essay." I'll ask for your permission if I decide to use it. You're an inspiration.

        Kelsie said...

        Do you have a slug problem in Missoula? They are eating my garden alive!! I've tried beer in a lid, crushing up egg shells to cut those suckers up but as soon as I water the egg shells get washed away. I, like you, have wee ones that I'd like not to harm with chemicals. Do you have any ideas?

        Tina said...

        I have quite a few gardening questions so this post is perfect for me!

        This year I planted my first real vegetable garden. It is about a 8x11 plot, maybe a a little bigger. I have one row of tomatoes, one of cherry tomatoes, one of green peppers, one of red peppers, and one of cucumbers. The cucumber plants are mostly out of control - trying to wind up onto everything around them. I redirect them whenever possible and bought a small metal fence for them to crawl onto. The pepper plants seem to be mostly thriving, although many of them have holes in the leaves - it seems like something is eating through them. They have had flowers and are starting to grow actual peppers although the peppers themselves are still too small to know if they are/will be damaged by the same culprit that is attacking the leaves. I am happy to report my two varieties of tomato plants are doing ridiculously well, they were a mere 3-5 inches when I planted them about 7 weeks ago and they now stand over 5 feet tall with tons of tomatoes growing on both.

        On the other side of our yard we also have a strawberry patch that is on it's 3rd year. The previous two years we had quite a bit of fruit from the plants despite it's pretty small size, however this year we didn't get any fruit from our big leafy plant. Is this normal for a strawberry plant? Somebody told me that it is normal for them to have a poor production of fruit once every few years.

        One last thing - we just planted our first raspberry plants this weekend. They were already started and purchased at the garden centre and transplanted. Should we expect them to bear fruit like our strawberry plants did their first season?

        Sorry for all the questions Nici... none of my friends/family garden and I find that trying to find answers to my questions almost always come up with answers that are very indirect and lead to more research before I can discover what my solution/answer may be. So frustrating!

        MT Goddess said...

        Having worked @ the plant clinic @ missoula's co extension, I can't stress enough proper diagnosis- as you said! Every(well most) county in every state has a local county extension service funded by your tax dollars, use them they have so much wonderful free information on horticulture, agriculture, home economics and even things like canning! Thanx for a great post!

        TRB Holt said...

        VERY enlightening Burb!


        ps....love your bush bean forest!

        clove's corner said...

        One year we thought voles were eating everything as plants first emerged. But one after-dark inspection following a rain storm proved that it was slugs! Tons and tons of tiny little slugs. I'd never even SEEN slugs in this part of the country prior to that night.

        StephM said...

        Love this! I'm in my 6th year of gardening and, while I do get discouraged some years, overall there has been progress every year.

        Baby By The Sea said...

        I love how much I learn from all your garden knowledge. I've got the same cauliflower issue going on, so this came at the perfect time.
        This whole gardening venture has been so interesting. Last year, first island garden with crowded, overwatered raised beds. This year, a whole lot of trust in a few plants and gaining the ability to thin, love and water.
        Just the other day, while I was harvesting mint for a mojito, lettuce for a salad and checking on my pole beans that look straight our of Jack and the Stalk someone said, "Wow. I didn't know you're a gardener." "Yup. I guess I am."
        Funny, how so much can grow under your care when you trust it's own vibe.
        So, thanks for all your info you pass along. Really, it's amazing how much you know about gardening.

        jen said...

        you know what kills me this year? everything i planted is growing steadily and happily! {knock on wood} i haven't ever had a year like this ... and i even tried (again!) some things that did poorly in past years. awesome.

        jen said...
        This post has been removed by the author.
        rebecca said...

        ,,,love your front & back gardens, thank you for the always insightful gardening advice,,,dig the "hippie" banjo man, you should have encouraged him to sing over your garden to nourish and spread the love!,,,(smile)

        Lee said...

        I kinda wish that the plants called 'hens and chicks' were edible as I can grow the heck out of those! But I've not yet found the motivation to focus my time and attention on the raised bed in my back yard.

        My kids planted some squash and bean seeds back there and they are growing well, but when I went to weed it this weekend, my 2-yr-old son decided to help and he pulled half the beans up when my back was turned! My little helper, sigh. ;)

        Jill said...

        What an excellent and informative post. I appreciate it and will pass it along.

        dig this chick said...

        Tina: I don't know much about fruit. But I do know that different varieties have different yields. Like, "ever-bearing" strawberries produce several crops throughout a season whereas "June-bearing" produces one large crop and "day-neutral" produce several crops but don't put out runners....

        There is so much nuance to growing raspberries! The A-Z guide I mentioned has some good info...sorry to not be more help!

        dig this chick said...


        Look here to figure out kale:


        good luck!

        dig this chick said...


        Pruning tomatoes! It's easy and fun. I don't pinch off the flowers although I know many do. The point to pruning is to encourage apical (up!) growth and fruit production. I snip off the lower branches to make my plants more tree like and then random leaves...not that scientific but I think about wanting to encourage all that sun and water and nutrients to go into as few parts as possible to bring on the tomatoes!

        dig this chick said...


        Wow. You are really into the feline shit over there. We have two cats and I don't have a problem...you must have some desirable soil!

        Cats usually bury their poo...where are your kids stepping in it? One thought I have is to create a REALLY desirable space for pooping. Like a sand pile behind a bush? Bird netting would do the trick. Cat's won't poop where they can't dig!

        Minnesotagal said...

        Oh bizarre! I read your post last week and thought. Whew! Glad I don't have any garden issues this year, now that I've relocated raised beds to sunny spots. But then this morning I woke up to two de-leafed brussels sprout plants. I hunted and hunted and then this afternoon finally found a cabbage looper. Never grew them before so wasn't even aware this was a possibility. Your post hopefully saved the rest of my plants!

        I love you gardening advice and am glad for a post after such a long while. Thank you!

        Minnesotagal said...

        *your* - why oh why can I never seem to type the ending "r" in any post ever!!

        FinnyKnits said...

        Great book reccos - I'll have to check them out. I'm a big fan of Rodale's Guide to Organic Gardening (I have many editions) and I have one companion gardening book that's good, though I have no idea what it's called (Great Garden Companions? That might be it.)

        Anyway, amen to this post. I'm a diagnose-aholic and am always on the look out for no-no behavior in the garden.

        This year, so far, nothing terrifying, just really need to pull out some nasturtium so that the vegetables can see the sun - those things are bonkers.

        And the potatoes are back for a second try - no bermudagrass gumming up the works this year. Jerk bermudagrass. HATE IT.

        Also - can not believe all your squash plants. Get ready to move out.

        www.preparingforthebaby.com said...

        Hi Nici,

        Have you ever had tiny flies that congregate in squash blossoms? I looked online and can't figure out how to get rid of them.


        Puget Sound Mama said...

        Nici- Great post and thanks for the ideas and resources!


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