Sciency Answer: Too much compost? (Plus! Fun with lime!)

Leslie, who blogs over at Mountain Plover blogs.icta.net/plover, send me a great question.

My question is about adding compost... can you add too much? And if so, what harm does it

In my master gardener training, we were told to always recommend adding 4 inches of organic matter, dug in 8 - 12 inches. Colorado soils are notorious for their lack of humus. However, my brother-in-law (who lives near Denver) had a soil test (from an independent lab) come back telling him he had too much compost! (He has been growing veggies for a number of years, adding compost and shredded leaves to the soil every fall.) Apparently, this was throwing his other minerals out of balance. They actually recommended adding lime and gypsum, two things CSU told us to avoid. Now I'm totally confused.

"The compost and leaves have narrowed the calcium to phosphorous and the calcium to potassium ratio. Both should be 18 to 1. The reason a small amount of limestone is added is because calcium and potassium compete for space on the clay colloid. When limestone is applied it will push potassium off the clay colloid and then be taken up by plants or will leach below the root zone. This is a little trick to help reduce excessive potassium faster. The gypsum is applied because it will help correct a serious situation in your soil: excess sodium. Once applied, the calcium and sulfate in gypsum will disassociate. The sulfates combine with sodium to become sodium sulfate and is leached in the presence of adequate moisture. This will help reduce your sodium level. Having sodium at 166ppm is much worse by far than having calcium at 8000 lbs. per acre or even higher. High calcium levels are not that much of an issue. Calcium nitrate is applied to bump up the nitrates in the soil for quick, early growth in the spring. The amount of accumulated calcium will be negligible."

Whew! What a lot of great questions! And a lot of excessively technical language from the soil lab. I'll try and break this down in bits and see if we can make sense of it all.

Fertilizer Vrs. Soil Amendment

When thinking about adding stuff to soil, I like to mentally break things down in to two categories: Soil amendments and fertilizer. I think of things like peat moss, charcoal, sand, as soil amendments. Their primary purpose is to change the texture and structure of your soil so it is a better space for plant roots and beneficial microorganisms to grow in. Fertilizers, on the other hand, are plant vitamin pills, providing specific chemicals they need to supplement their main diet of carbohydrates they make from water, sunlight, and air. It is pretty hard to overdose on most soil amendments. You can't really have too much organic matter in your soil – after all, peat or coir based potting mixes are essentially 100% organic matter. Fertilizers, on the other hand, are usually damaging to plants at high levels, just as you can overdose on almost any vitamin.

Compost is, of course, both a fertilizer AND a soil amendment. Compost has a lot of organic matter which improves soil texture, and it also has varying amounts of nitrogen, phosphorous, etc. The exact amounts will vary widely depending on that your compost is made from, but certainly you can add too much fertilizer by adding too much compost. The most common compost over-dose, in my experience, is adding way too much nitrogen when using composted manure, but you can overdo other elements as well.

To lime or not to lime?

The rest of Leslie's question is interesting because it make, once again, the point that all gardening is local. The soil testing lab recommended adding lime and gypsum – but her Master Gardening training at Colorado State said to avoid both of those! What gives?

The usual reason to add lime or gypsum to soil is to correct a calcium deficiency, and/or to make a soil less acidic. Where I live, we get around 30-40 inches of precipitation a year and all the water leaches out the alkaline chemicals, usually producing an acidic, calcium deficient soil. Around here, adding lime is pretty much standard practice. Leslie gardens with only 16 inches of precipitation a year, and that lack of water lets calcium build up in the soil, so adding more is just making a problem worse. There are exceptions to the rainfall-soil pH connection of course... lucky people like Gail who, thanks to limestone bedrock, have alkaline soil despite a wet climate. I gardened briefly on limestone when I was at Ohio State... it was a pain. Suddenly rhododendrons went from over-planted and boring to difficult and desirable. Because wet, alkaline soils are rare, it is hard to find plants adapted to those conditions.

All of which is a bit beside the point in this case. The soil lab is recommending lime and gypsum here for a different reason. Leslie's brother has too much potassium and sodium in his soil, and adding lime and gypsum is a kind of chemistry trick to let those chemicals leach out of the soil faster. It will increase the amount of calcium in his soil, which isn't a good thing, but having lots of sodium is a much WORSE thing, so is the best option for the healthiest soil.

Get Tested

The bottom line here is: get your soil tested periodically by a qualified lab in your area. Soils vary radically depending on your climate, they type of bed rock you have, and how you manage it. Compost is a catch-all term, and composted cow manure is going to be very different than composted yard waste or composted coffee grounds. Find out what your soil is actually like now, so you can make the right choice on what to add to it in the future.

Have a question? Get a sciency answer! Just e-mail me (engeizuki at gmail dot com) or ask one in the comments!

Friday cartoon: Snow is pretty but...

Snow is pretty but...

Magnificent Mums

Okay, I know what you are thinking. 'Magnificent' and 'Mum' are not two words that usually go together. Those little round blob mums you see for sale every fall tend to inspire, at best, words like 'reliable' and usually something along the lines of 'boring.' That's how I thought of mums, until my first trip to Japan, where I took this picture:

You know you are in Japan when the mums are bigger than the trees...

As an aside, I didn't see this in a botanic garden or something. This was just the display on someone's front porch I saw wandering around Nagoya. Grabbing a pot of mums at the supermarket to spruce up the front of the house takes on a little different meaning in Japan. 

Seeing mums like these made me think completely differently about them, made me realize that those little lumps of color you see here are just a tiny, tiny bit of the incredible variation in this group of plants.

Since I took that photo, almost a decade ago now, I've been keeping my eyes open for more interesting varieties, with little luck. Until recently, when I found some. Well, not some, a LOT. A whole treasure trove. Turns out a Faribault Growers has a whole line of varieties that are not only gorgeous and voluptuous but also fully winter hardy in Minnesota. Here are a few photos taken from their website:

Luscious. Just luscious. I'm going to stock up my garden with them this year and celebrate fall with a little drama.

Sciency Answer: Damping off

Back in November, when I posted my Great Catalog List, I sang the praises of buying seeds. In the comments, Lisa said she would like to grow more from seed, but has trouble with things damping off, and asked if I could give some help.

So, today's Sciency Answer is: Everything I Know About Damping off.

What is it?

 Damping-off is a generic term for a number of disease (fungi and other bad stuff) that attack young seedlings. The seeds sprout, they look all happy, and then they start wilting and collapsing. It is pretty devastating, but quite preventable. You'll usually have problems with damping off if you have a LOT of fungal spores in your seed starting area for some reason, if your seedlings are weak or stressed, or if you keep the soil to wet. By following a few guidelines, you can keep your seedlings happy, the fungi unhappy, and your seed starting trouble-free.

Use sterile, high-quality potting media

I use Baccto, a sterile peat-based media, for my seedlings. There is nothing special about that brand, it is just what my favorite garden center carries. I know peat is controversial environmentally but it is also the best -- at least in my experience, and in the experience of most growers I have talked to. Feel free to disagree with me in the comments. I use a variety of other media for bigger pots and containers, mixing in my own compost and good garden soil along with peat alternatives like coir. But seedlings need the best, and since you only need a tiny container to get seedlings started, a little high-quality potting media goes a long way. Starting with sterile media means you aren't putting seeds into a giant population of pathogens waiting to consume them. I've read recommendations to top your media with a very thin layer of coarse grit, the reasoning being it will dry out quickly, making it difficult for fungi and friends to grow on the surface. I've never tried it, nor have I ever seen it used commercially, but it makes sense, and might be worth a try.

Use sterile containers

Either buy new ones for each batch of seedlings, or give them a soak in a bleach-water solution and rinse them thoroughly. Old, unsterilized containers can be loaded with potential disease.

Keep the air moving

This is critical. In perfectly still air, a layer of nearly 100% humidity hangs right over the moist soil, making ideal conditions for all the nasties to grow and attack your seedlings. A fan very gently keeping the air circulating breaks up that super-high humidity layer and will make a dramatic reduction in your disease problems. HAF (Hortizontal Air Flow) fans are ALWAYS used by commercial growers and should be by home seed starters as well.

Give them enough light, sun light if possible

If seedlings don't have enough light, they become long, leggy, and extra susceptable to disease. Many commercial available seed-starting light systems simply don't have enough bulbs to produce healthy seedlings. I use two big florescent shop lights side-by-side, for a total of four florescent bulbs over my seedlings, keeping them vigorous and healthy enough to fend off pathogens. Sunlight is extra beneficial, because the UV rays provide a sterilizing effect, knocking back the disease organsism at the soil surface. In cold climates like mine, sunlight usually isn't an option because I'm starting most of my seeds in the later winter when it is way too cold for my seedlings outdoors. However, when I do get a rare warm, sunny afternoon, I always rush my seedlings outside into a sheltered, lightly shaded spot. One year, I neglected to have a fan running in my seed starting room, and a tray of tomato seedlings started collapsing left and right, but a few hours of sterilizing sun stopped the disease in its tracks.

Keep 'em warm, with bottom heat if possible

If your house (or wherever you are starting your seeds) is on the cool side, giving your seedlings a bit of extra heat will help them germinate and grow quickly, getting them past that vulnerable just-germinated stage faster. Some seed companies, like Johnny's, will list the best temperatures for germination of each plant. If I can't find specific information for a plant, I aim for the upper 70s F (~25 C). The extra heat is best if provided from below with a seedling heat mat. Bottom heat encourages the roots to grow rapidly without causing the stems to grow long and floppy, producing healthier seedlings -- and healthy, happy seedlings resist disease the best.

Don't keep them to wet

Seedlings have tiny root systems, and can't be let to dry out too much, but keeping them constantly soggy is asking for trouble. I never let the soil dry out until the seeds germinate, but once they're up and have some roots, I try to let the very surface of the soil get a little dry before watering again. It can be a bit of a balancing act, but if you are doing everything else right, you'll have some room for error on the watering.

In an emergency...

Sometimes, despite your best efforts, your seedling start damping off. As soon as you see a seedling wilting despite the soil being moist, you know you've got a problem. First, get the diseased seedling, the soil and other seedling around them out of there as quickly as possible. One they're infected, you can't save them, and they'll only spread disease to your other seedlings. Then you need to keep your other seedlings from dying as well. I like treat them with hydrogen peroxide, watering them with roughly 1 part hydrogen peroxide from the drug store to 9 parts water. Hydrogen peroxide acts directly to sterilize the soil, and it also is used by plants to signal their natural defense systems to get up and running, so watering with it acts like a warning: "Hey! Damping off is coming!" 

What about commercial fungicides?

I don't spray any sort of pesticides (synthetic or organic) in my garden. If a plant can't cope, I pull it out, and find something better to grow. But I think fungicides make some sense for seeds and seedlings. When you spray a whole plant in the garden you have to use large quantities of the chemical and there is a high potential for it to drift, leach into ground water, and disrupt natural ecosystems. But treating a flat of seedlings under lights in my basement requires a tiny quantity of chemical with virtually no chance of it getting out into nature. That being said, I've never used fungicides on my seedlings -- the methods outlined above work fine for me, and I haven't seen the need. If you do, just be sure to do your homework to find the safest, most effective one possible, remembering that organics can be toxic and dangerous too!

Starting healthy seedlings isn't hard, provided you take the time upfront to create a seed starting area that promotes growth by seedlings not fungi. Now go buy some awesome seeds!

Have a question? Get a sciency answer! Just e-mail me: engeizuki at gmail dot com or ask it in the comments.

Fabulous but forgotten

This post is part of a group blogging project on great old fashioned plants... see links to the other amazing contributions at the bottom of the page.

When I was in Buffalo last summer, we visited a public trial gardens. They had planted out all sorts of the newest, latest, greatest, and most exciting new varieties of annuals and perennials. And then there was a row of Dahlias. Big, impossibly lovely dahlias.

As people leaned in for photos we chatted with the director of the gardens, and he said the dahlias weren't actually part of the trial. He'd just had some extra space, so he stopped at the local big box store, grabbed some random dahlia tubers and put them in to fill the spot.

And they were totally stealing the show – and not just with us, he said everyone who visited commented on them.

Let me repeat that: all the newest, most exciting, hot-off-the-press varieties couldn't hold a candle to a handful of random, no-name dahlias.

photo credit

 Sometimes really great, slightly old-fashioned plants get lost in the flurry of everything that is exciting and new. New is great – I love new plants (and like making new plants) but I think it is time we took another look at dahlias.

photo credit

Quickly, let me run down why dahlias are so freaking awesome.

photo credit

You can get them just about anyway you want them: Tall plants, short plants, tiny flowers obnoxiously huge flowers, doubles, singles, simple, frilly, reds, yellows, pinks, mauve, purplish, basically any color at all except blue. They bloom all summer, have not serious pest problems, and some even have lovely dark purple-red foliage. They look great in the garden, and they are spectacular as cut flowers.

Perhaps my favorite thing about them is: Winter doesn't matter. Winter is a total non-issue. With so many of my plants, I go to great lengths, tucking them into sheltered nooks, building raised beds to give them perfect drainage, I cover them, fret if there isn't enough snow. With Dahlias, I wait until frost, then grab a garden fork, pop them out of the ground, let them dry a day or two, wrap them in dry newspaper, shove them in a bag, and dump them in the basement. It is practically effortless, and no matter what Old Man Winter throws as me, I know they're fine. And even if that tiny bit of work seems like too much, they're cheap enough you can just let them freeze and treat them like annuals.

See other posts on great old-fashioned plants:
From the fabulous Frances
the excellent Ryan Miller (whose idea this was!)
And the remarkable Matt Mattus

Fuchsia decidua: THIS close to amazing

Last year I wrote a post getting all excited about ordering seeds for Fuchsia decidua from Gardens North.

It germinated easily, and grew happily all summer, with really quite attractive reddish leaves.

As fall came along, I brought it inside, let the soil dry out, and most of the leaves dropped off. Then, just as advertised, the nearly bare stems started pumping out flower buds. Lots of them. Big clusters of tiny buds that grow and grow...

They get to the point where I'm expecting them to open soon... and then they fall off. It is rather devastating. Because the amazing thing is these little plants starting sending out buds back in November (I think) and they are STILL at it! If only they would all bloom instead of falling off, it would be an incredible multi-month long display of flowers!
But... they ARE falling off, I don't know what to do about it. I have a couple theories: Maybe my house is too cold (55 at night, 64 during the day) or maybe the humidity is too low (we run about ~40% humidity most of the time) or maybe I'm not watering them enough. At first I wasn't watering them at all, figuring that when it came to a dry dormant period they wanted it DRY, but now I'm trying to keep them very slightly moist (I don't want them rotting out either...) so we'll see if that helps. If anyone else has ideas, please let me know! I want this to be my favorite winter flowering houseplant... if only I can get it to flower.

Friday Music Video!

No cartoon this week... Instead I made a music video. It is, as you might expect, rather awful -- my singing recorded on a $10 microphone generally used for skyping with the family, the video recorded with my regular point-and-shoot camera, and the audio is dreadfully out of sync with the video (tip: Don't change the lyrics AFTER you shoot the video...) BUT: it was fun. So now you have to listen to it. And like it.

This idea started in a conversation with The Soil Sisters in Buffalo last summer. The lyrics started with ideas from Jan (I think? I don't remember now) then changed significantly by me. My friend Rachel was videographer, and that's my incredibly sexy boy friend Jason playing the guitar shovel. If you aren't familiar with the original song, it is here.
As I said... it was lots of fun. Now I want to do Lady Gaga and Mika

Macros in a mason jar

I've never entered Gardening Gone Wild's photo contest before, but I've been wanting to get more serious about my photography, so I thought I should dive in. And, David Perry is judging this month's contest and I ADORE David Perry.

So, I started playing around with the macros in a mason jar concept. I didn't have a mason jar, so I tried various glasses, just to see how it works.

A single aloe flower in a juice glass looks kinda cool...

And the effect of a rosemary flower in a shot glass is kind of trippy. I decided to get more complex, and raided the garden for berries:

Which is kinda... meh. Doesn't grab me. Too busy, I think.
So then I got playing with textures, backgrounds, and other things I had in the house. I made a bed of Job's Tear's (Coix lacryma-jobi) and put a few flowers from my Pelargonium 'Vancouver Centennial' on it.

I'm like this better. More drama. More contrast. Then I pulled some sprigs from my rosemary bush.

And this, I think is my favorite. And my submission for the contest. I can't wait to see what everyone else enters!

Friday Cartoon: Color Contrast

I love winter. I love snow. A lot. This is one of the reasons why.

The 2011 Veg Plan

I have already (I'm so organized this year!) put in almost all my vegetable seed orders, gone through my boxes of old seeds, and figured out what I am going to be growing. Here's what my current "To Grow" list looks like in the form of a mind map: (click to enlarge if you want to actually read it) (and don't make geek comments about me planning the garden this way... you know you are all just jealous with your lame spread sheets.)

SOOOO much fun! I'm going to have a truly outrageous amounts of green beans and peppers. Not to mention tomatoes. Yes, I only have 5 tomatoes listed, but 4 of those are breeding populations in progress, and I'd like to have at least 20 plants of each... Other fun things include trying to grow quinoa, my search for the prefect broccoli, and my various on-going corn breeding projects!
Next I have to figure out where I'm going to plant them all, and I start shopping for flowers and other pretty plants. Yay for planning season!

Sciency Unreliability

Winston Churchill once famously said “Democracy is the worst form of government except for all those others that have been tried.” I think the same could be said of science.

I was thinking about this after my recent “Sciency Answer” about variegated plants. After I posted it, I had a couple of conversations with Kelly Norris on the topic. He read the studies I cited to support my explanation, and wasn't impressed with their technique and reasoning. I (obviously) was. The upshot is that I'm pretty confident variegation in wild caladiums (and other plants) is a disguise to prevent insect damage, and Kelly is very skeptical. Which is totally normal. Scientists often disagree about what studies mean, because scientists know a very important thing about science: It is often wrong.

Since I'm now in the business of dispensing sciency answers, I thought I should talk about that. About why science is so often wrong, why some of my answers may prove to be wrong. There are lots of reasons, but I think one of the biggest problems is people like me -- Graduate students.

Graduate students like myself are the people in the lab (or field or hospital) doing the actual work of most of the scientific research going on these days, and we have a HUGE conflict of interest that effects any sort of research we do. We desperately want to graduate.

In order get my PhD, I do research. In my case, research on petunias. I perform experiments, write up my findings as a dissertation, and hey presto, you have to call me Doctor. Unless, of course, my research doesn't work and I don't find anything interesting. To use an extreme, completely made up example: if I was studying the effects of chewing gum, and found that it caused cancer, WOW! That's shocking! It gets published in a fancy journal, I get a degree, I get a job, and everything is wonderful. But if chewing gum doesn't have any effect at all... I'm screwed. No chance of a good publication, no job, and maybe even no degree unless I start over with a new line of research.

This isn't just true for graduate students. University faculty need to make tenure, they need grants, and to get all that, they need publications. Publications from research with big, interesting findings.

In response to all the pressure to find results, people do sometimes make stuff up, but most of the time they do something more subtle, perhaps even unconscious. They overlook alternative explanations, massage their data, or keep asking the same question a different way until they find something that passes the test of statistical significance. Chewing gum may not cause cancer but it must do something... gum disease? Jaw injury? Stress? Divorce rate? Ask enough questions, and even if just by chance, the numbers will tell you one is right.

Because of that, new scientific findings tend to overstate the case – they find big, dramatic effects that sometimes prove to be weaker, or nonexistent in future studies. Science does however, eventually, tend to correct its own mistakes. Since no one currently believes chewing gum is dangerous, a study finding it to be safe is boring and unpublishable. But if someone else had said it did cause cancer, debunking that finding would be very publishable. That's why in significant areas of research we get dueling studies (Eggs are good for you! Eggs are bad for you! No, they're good for you!) but over time, eventually, we can look back over all the studies, compare them, and finally (hopefully) come to a conclusions that is close to actual reality.

That is why, despite all its flaws, I believe in science as a powerful way to understand how the world really works. Just don't confuse science with the actual truth. Truth is something we strive for, but can never really, absolutely, know.