Spring Fever

It doesn’t take much to get a gardener’s motors started. Just two consecutive days above 60 degrees usually does it. The forecast isn’t that good yet but my weatherman says that 7 of the next 10 days will have high temperatures in the 50’s. And it should be relatively dry. But it will be below freezing on several of those nights.

Time to plant the tomatoes? Not quite. Many of the things we grow in our gardens are tropical and will not tolerate cool temperatures, not to mention a freeze. In the vegetable world, we’d consider all of the vine crops (cucumbers, zukes, melons) to be most cold sensitive. Tomato, eggplant and pepper will tolerate a bit more cold stress but still prefer temps above 45 at a minimum. So, in Bucks County the vine crops go in about June 1 and the tomato/eggplant/pepper group in mid-May.

So, if you’re itching to plant something, what can you do? Start with hardy perennials. They don’t mind a freeze. All of the fruiting plants such as strawberry, brambles and fruit trees should be planted ASAP…as soon as the soil is fit to work. If you were thinking about planting trees and shrubs in the landscape, now if the time. No worries about cold temperatures here.

In the vegetable realm, think about leafy vegetable crops such as lettuce in a week or two. Onions and shallots can go in then, too. Root crops such as beets and carrots also tolerate early spring weather.

You can enhance the growth of early seeded crops and protect from wind and cold by using cold frames or floating row covers. In addition to cold protection these techniques increase daytime growing temperatures and accelerate growth.

In many areas the soil is still simply too wet to plant regardless of temperatures. Those of us with raised beds have an advantage since they dry out sooner than soil. Never try to work soil that is still saturated. You will destroy soil structure.

So, rake those garden beds, finish pruning fruit trees and shrubs, plant a tree or shrub, start a new compost pile, get a soil test and sharpen your hoe as we wait for planting season.

Pansies have appeared in the gardnen centers and are a great way to liven up a late winter/early spring landscape. They love the cold. Put them in a planter box with potting soil if native soil is too wet.

Spring has Sprung

Ok, officially, Spring arrives on March 20 this year but I have observed several things that tell me it is already here.

Silver Maple is in full bloom. This isn’t a very showy bloom but it means a lot to honeybees who are looking for their first sips of nectar and loads of pollen. Red maples were not far behind. You can easily see the swollen, red buds on this common tree. These species bloomed even before Cornus mas, the Cornelian Cherry Dogwood, which is an early bloomer. In fact, I saw a stunning specimen of this tree on the edge of Morris Arboretum yesterday. Blazing yellow. Just drive a few miles south to Philly if you want to get a preview of what is in store for us in the northern suburbs.

The first summer annual weeds have germinated, too. Prostrate knotweed, which is one of the first to emerge has taken advantage of the micro-climate along the stone pathway leading to our office and has sprouted. By contrast, the winter annual weeds, which began growth last fall, are already beginning to bloom. Purple deadnettle, common chickweed and bittercress are flowering in warm, sheltered areas. These species will form seeds later this spring and then naturally die. The seed that they drop will wait patiently until fall when the cycle begins again. Ain’t Nature wonderful?

I am not much of a bird watcher so I’ll leave it to others to announce the bird signs of spring. I did happen along a lovesick wild turkey last week… dancing in the middle of a rural road.

Countdown to Seed Starting

Although it is only February, folks are getting antsy about planting. I recently spoke to a person who had 50 lbs of seed potatoes scheduled for March delivery. When we had finished talking, that had changed to 25 lbs of spuds and a later delivery date.

This reminded me that lots of folks have questions about when to plant various crops. Part of the problem is that books often give a very wide range of dates or otherwise mislead readers. Books rarely get specific enough for local conditions.

So, where do we start? In Bucks County, the last spring frost usually occurs about mid May. Actually two key dates are useful. The median frost free date (50-50 chance of a frost) is about May 1 and the 90 % frost free date is about May 20, northern Bucks dates being later than southern Bucks. These dates are very useful when determining when to start transplants indoors.

Check out Penn State’s handy guide to seed starting for common veg crops. It details how long certain species should be grown indoors prior to transplanting and when they can be planted outside . Let’s take tomato as an example. If I am conservative and don’t want to risk frost injury, I’ll plan to set out plants on May 15. It takes tomato seed a week to germinate and I will grow it for 5 weeks before transplanting outside. So, working backwards six weeks (1 + 5) from May 15, I see that seeding tomato on April 1 will put me in the ballpark. If I am a bit of a risk taker, perhaps I’ll start them in late March and hope for a warming trend in early May. You get the idea.

Of course, some vegetable crops are seeded directly into the garden. Here you need to know their tolerance for cold. Peas tolerate cold well and can be direct seeded very early (late March/ early April)while plants in the squash family must wait until June.

There are other factors besides temperature involved. Some garden soil remains wet late into the spring. So, although those potatoes will tolerate cool soil… cool and wet soil can spell trouble. Waiting a week or two can be the difference between success and failure.

For a complete set of common vegetable crop fact sheets see this site. They contain information on planting dates as well as varieties, fertility, common pests, harvest suggestions and more.

Thanks to Kansas State University for the image of Broomcorn seed

Witchhazel blooms

There’s nothing like a bit of bloom to remind us that spring is just around the corner. Today I noticed ‘Arnold Promise’ Witch-hazel (Hamamelis x intermedia) blooming in Doylestown. Its yellow petals are thin and strap-like; held in loose clusters.

There are several Witchhazel species used in landscaping but the most popular are these hybrids of Japanese and Chinese species. ‘Arnold Promise’ may be the most popular and it showed its colors on February 12 after we had a nice day of 60 + degrees.

This multi-stemmed shrub is a nice addition to almost any landscape and is adapted to a range of growing conditions. It will grow in full sun or partial shade and get to be about 12 feet high and wide with an upright growth habit. Its best characteristic is the early bloom but the summer foliage is a nice, medium green color and it is virtually pest free. The blooms even have a bit of fragrance.
There are other Witchhazel species. For the native plant lover, look for Common Witchhazel (Hamamelis virginiana). It’s the last plant to bloom, by my reckoning; usually in mid-November. It also has beautiful yellow, strap-like flowers. Sometimes they are obscured by the fall foliage but I usually get to see them lighting up the woods after leaf drop. This plant will get even larger than the hybrid described above and has a more horizontal growth habit. Seems to tolerate moist sites. Would be great in a naturalized border setting.

Next on my woody plant bloom list… Cornus mas. Maybe next month. Spring is coming.

PS image by Al Dolson

Wood ash... the wonder trash.

There’s an old saying…"If you heat with wood it warms you twice. Once when you cut and split it and again when you burn it.” There is a final benefit to heating with wood if you are a gardener…. wood ash.

Wood ash is high in several plant nutrients, most notably potassium. Most references say that wood ash contains about 5 % potash… slang for potassium oxide, K2O in the fertilizer biz. That puts wood ash right up there with many conventional bagged fertilizers as far as nutrient content goes. It would be (is) a 0-0-5 fertilizer. No nitrogen or phosphorus but a nice slug of potassium.

Potassium is one of the “Big Three” or primary elements that plants need in order to grow and thrive. It is always listed in third place in the sequence of three numbers on a fertilizer bag.

There isn’t much “organic” about wood ash since all of the organic matter is burned off in your fireplace or wood stove. But most organic gardeners are more concerned about the natural part of stuff so wood ash is accepted. So everything is hunky-dory, right? Maybe.

First be sure that what you burned was wood, not stuff that might leave nasty remains. And that includes pressure treated wood, which until recently usually contained arsenic. Next, it is important to realize that wood ash is quite alkaline which means that it will increase soil pH (lower the acidity). It acts like a liming material. Still with me?

The practical matter is, while wood ash does contain essential nutrients, you can have too much of a good thing. If you have a big wood burner and a small garden you can drive soil pH into an extreme range and over apply potassium. Neither is good for plants. So how much should you apply? Depends on what you’re growing and the current status of your soil fertility. If you really want to know, get a Penn State Soil test. If you have to take a guess, don’t apply more than a pound or two of wood ash per 100 square feet until you get more information. If you just want to get rid of the dang stuff, sling it around the lawn. Wood ash is light and with the right technique you’ll be applying such small quantities that it will be hard to over apply it. Since wood ash is alkaline, avoid applications to areas where you are growing acid loving plants such as azaleas and blueberries.

Saving Seed

There’s nothing like a cold winter day to get you thinking about spring. So last weekend when it was 2 below zero (still zone 6, see previous blog entry) I did a seed inventory. I was about to start filling out an order from my favorite catalog when I realized that I still had a lot of left-over seed. So I sorted and evaluated my stock. Wow! Do I ever have a lot of lettuce seed! Some of it from 2005.

The question is: will that seed still germinate? It depends on the species and the storage conditions. In the case of lettuce, my references say it is one of the best at remaining viable… maybe 5 years under good conditions. My left over onion seed from 2003 on the other hand, is mostly dead.

What are good storage conditions? In a nut shell, cool, dry and dark. About 40 degrees F and very low humidity. Temperatures in your fridge are fine; the enemy is moisture. Sealing dry seed in air tight jars with silica gel packets or another moisture absorbing material is best. Dry powdered milk might be handier for many of us than silca gel. Just put a couple of tablespoons in tissue paper, seal with rubber bands and add to your airtight seed storage jar.

Is that how I store my seeds? Sadly, not. They’ve just been in the garage… dry but subject to a range of temperatures and fluctuating humidity. So I’ll lower my expectations. Experience tells me that for most species, germination percentage may be down but enough of the seed is viable enough to warrant keeping it. Just sow a bit thicker than with fresh seed. If I had the time (or if the stakes were higher)I’d do a germination test by putting seed on moist paper towels at room temperature and recording the percentage that sprout. I probably won’t get around to that either.

Ok, here’s what the books say about seed longevity under good storage conditions. 1 year : onion, parsley, parsnip. 2 years: okra, pepper sweet corn. 3 years: bean, carrot, pea, broccoli, spinach. 4 years: beet, cabbage, cauliflower, eggplant, pumpkin, tomato. 5 years: collards, cukes, melons, lettuce, radish.

Note that what happens is that germination percentage declines over time. They don’t all die at once. And storage conditions have a big effect. One reference I read described seed of many vegetable species with germination rates over 50 % many decades after being put into ideal storage.

How Cold Was It?

That’s a question that gardeners and farmers ask each other all of the time. The talk really heats up at several key times of the year: mid winter, when extreme low temperatures occur; late spring, when frosts can damage tender new growth and blooms; and again in the fall, when the first “killing freeze” signals the end of the growing season.

It is supposed to get a bit chilly later this week so I am sure there will be lots of conversation about the season’s lowest temperature, to date. The weather women (a major improvement over the weatherman) are talking about single digits on Thursday and Friday nights. Since most of Bucks County, PA is in USDA Hardiness Zone 6, that’s normal. In fact, if temperatures stay above minus 10 degrees F we are still within the normal average range for zone 6.

If you are not familiar with the concept of hardiness zones, click on the USDA link shown above and educate yourself. Zone designation is based on records of average low temperature that occurred from 1974-1986. The country is divided into 11 zones. The lower the number, the colder it gets.

Believe it or not, there is weather outside of the USA. I recall taking a stroll in Skibbereen, southern Ireland, a few years ago and admiring the Fuscia hedges. They were obviously hardy perennials there. This is Zone 9. The locals said it rarely went below freezing. The hardiness map says the average low temperature range is 20-30 degrees F. I note that my gardening pals in Nuremberg, Germany are zone 6, just like us. I would expect that the procedures I use for growing garlic would work there as well. Cold hardiness is a useful, international concept.

However, cold hardiness is only one important factor in plant growth. For instance, although the average low temperatures in southern Ireland look good for figs, I wonder if they get enough heat to ripen a crop. Rainfall, day-length and many other factors play a role in plant survival. I’m told that although Norway Maple is cold hardy in the southern states, it struggles under the high temperatures. Same thing with currents and gooseberries.

There isn’t much you can do about the weather but it’s important to consider winter hardiness when deciding what plants you are going to grow. Professional horticulturists and plant sellers use the USDA hardiness zones as an official and useful guide.

Of course, gardeners are always pushing the limits. I’ve got a fig tree and crape myrtle in my yard and they are both of these are zone 7 plants. I expect them to be severely injured by low temperatures now and then. Both have been killed to the ground. They re-grow from below ground parts that were not exposed to the killing temperature. Pushing the limits of hardiness zones is OK for the amateur but you’d be nuts to start a fig farm in zone 6.