Bulbs in a Climate Challenged World


If it’s happening in my garden, I’m fairly sure it’s going on in yours too, so yes, that’s right, the leaves of our spring bulbs are starting to come up already. I know, I know, you’re thinking that’s not good, right? But here’s the deal, and this is super important, there’s no need to panic. And even if you do, it’s not going to help because the main reason bulbs are peeking out of the soil this week is something totally out of our control ­– the weather. Were you anywhere outside this past Friday? Well of course your bulbs are going to push up a bit of foliage – it feels warmer now, in January, than it did for all of last year’s April and May.

Luckily, nature has built a failsafe into bulbs just for this eventuality. Most bulbs evolved in climates that had what I now refer to as “old-fashioned” winters. These are winters where it slowly gets cold, stays consistently cold, and then, ever so slowly, warms up in spring. My childhood was filled with winters like this, but no longer. I’ve written before about how iceboating on Mecox Bay was an all winter long local ritual, but in the last decade there’s only been a few years cold enough to bring boats out. I saw a few in 2011, again in 2014 and 2015 but only for the briefest window each year. January of 2018 started off good, but then had a thaw and winter (along with the ice boating season) sort of dissipated. Our climate has changed and these warm spells we’re having are confusing all our plants, including our bulbs.

However, bulbs are built in a way that works well with inconsistent coldness. First, the very earliest of bulbs have a kind of native anti-freeze in their cells, this is how you can have crocuses and snowdrops flowering in the snow, or be blooming before snow falls and then, once it melts, keep right on going. Secondly, and significantly more importantly, true bulbs (not corms or tubers) are built in layers with the flower stems independent from the foliage. These flower stems require a certain amount of time in the cold before they’re able to bloom. You know how even though we plant all of our spring bulbs at the same time, in the spring their blooms are staggered? This is because different species require different lengths of time to be triggered. Early bloomers like muscari and crocus require eight to 10 weeks of cold, while narcissus can need as many as 18, but for all of them, the temperature required for each of those weeks to count has to be at 40 degrees Fahrenheit or lower. So, even if the mild weather is encouraging foliage growth, it’s not going to encourage budding. Yes, you might be seeing daffodil leaf tips, but don’t worry, their flower stems are still counting days.

Besides, a little bit of foliage growth during freezing times isn’t that terrible. They might get frosted, yellow and die back, but that will just ensure your bulb goes back into dormancy. It’s what would happen in the wild, so please, don’t try and “help” your bulbs by burying those tips in piles of mulch. Even if the foliage gets damaged by the frost, there’s a good chance the bulb will still send up more greenery when the temperature is more appropriate. Dumping at this mulch on top of these tiny shoots at this point will either keep the soil warm and thus encourage more growth, or it the mulch will freeze and cause even more damage. Just leave well enough alone.

The only time we should do something is if it gets super weird (weather-wise) and we start noticing flower buds protruding. This is a different issue. If this happens, you get to decide if you want to try and protect it – if a flower bud gets frosted, it won’t bloom, or if it does it’ll be damaged and disfigured. If you want to try, please don’t use mulch, instead mound some dry leaves, sawdust or straw on top of them for protection, but make sure it’s not too heavy. And then, once it warms up, you’re going to need to remove your mound or it’ll hinder your bulbs’ normal growth. I’m more laissez faire, if my buds get frosted it’s normally not that big a deal. Sometimes these bulbs will produce additional flower buds to bloom when the weather is more appropriate, but, even if they don’t, the following year they’ll be fine. I’ll enjoy them then. Also, I normally so many bulbs that flower at so many staggered waves that I don’t sweat the few that get blackened.

Where this attitude won’t work is with tulips. These bad boys tend not to be perennial in their habits, so if their buds get frosted it’s sort of a bummer. This is the main reason I pressure people to plant tulips a little deeper than they think (or at least one of the reasons – I’m also, naturally, a bit bossy). Especially as the other reason spring bulbs pop up too early is that they’re planted too shallow. The rule of thumb is to plant your bulbs that’s three times deeper than their widest part. You have a tulip bulb that’s 1.5 inches tall and 2 inches wide? It needs to be planted with its top at least 6 inches below the surface, and for good measure I’d encourage you to go down at least another 3 inches.

You also need to wait until it’s cool enough before you plant your bulbs. Plant them too soon and you risk encouraging premature sprouting. This is also why I try not to ever give a specific date for when to start planting. Instead I tell people to wait until the evening temperatures are consistently 40 something degrees Fahrenheit or lower. People are always worried that they’ve missed their planting window, that they’re planting too late when it’s actually much worst to plant too early. This year I was still planting tulips right up until New Year’s Eve day so let’s worry less about the date and instead watch the temperature.

I should digress here for a second to mention that it’s quite common for established grape hyacinth clumps to send up their foliage significantly early (in the fall actually) and for that foliage to loll about and lay on the ground all winter long and then to fade once the plant has flowered. Or if those leaves get frost damaged, the bulb will just shoot out some new ones once spring rolls around. So, don’t assume your muscari’s foliage is a harbinger of climatic change. It is, slightly, when winters were colder this happened less frequently, but truly, grape hyacinth foliage in the fall or winter is normal, tulip and daffodil foliage, not so much.

The only thing we can really do to help deal with that foliage is to take a couple of nice, deep breaths. And yes, I know the Farmer’s Almanac said this was going to be an awful winter, so don’t get too excited, there’s still time.

Paige Patterson still has dahlias to dig up, so is grateful for this delayed winter.