Dr. Robert Gough is Associate Dean of the College of Agriculture, Montana State University, founder of the master gardener program there, and the author of several books, including Best Garden Plants for Montana, which he authored with his wife, Cheryl Moore-Gough.
Send your questions to drbob@zone4magazine.com, or mail to Zone 4, PO Box 3208, Bozeman, MT 59772. Please include your city and state, as they may have a bearing on Dr. Bob's response.
Rocks in the Garden
Q
My Husband and I are finally putting in a garden this year. As we started to dig, we are hitting a lot of rocks!! My husband is digging away but making slow progress. I am 6 months prego and not as helpful as I would like to be. Should he borrow the neighbors rototiller and forgo the shovel? Are we digging in a bad spot? Any advice would be very welcome because I would love to get the garden going and save my poor hubby from killing himself.
A
I don’t know how large the rocks are or how many you have, but I know they are always a big problem for gardeners. If they are fairly small a rototiller may be the answer, but you will still have to pick out the rocks. Be sure you get a rear-tine tiller so the weight of the engine lies directly in front of the blades. Rear-tine tillers are easier to handle than front-tine tillers in rocky or hard ground. If the rocks are too many or too large for the tiller and hand-picking then consider raised beds. These are simply made, rest above the poor soil, and are filled with a good mix of soil/peat moss/and other amendments. Raised beds warm faster in spring and allow for earlier planting. So, if the tiller doesn’t do the job, go to the raised beds and be a happy gardener.
Tomatoes by August
Q
I am doing my best to get red tomatoes by early August (under my cold frame), and am wondering if they would pollinate faster if not covered by the cold frame?
A
You have your work cut out for you if you want ripe tomatoes by early August. For fruit you must have pollination and fertilization first. Tomatoes are able to self-pollinate (no insects required) so long as the plants are exposed to shaking by wind or by mechanical means in order for the pollen to drop onto the stigmas. Tomatoes grown where there is absoutely no plant movement will have poor fruit set. It won’t hurt if you shake the plants a couple time each day for added insurance. You did not state whether your frames are opened or closed. I suspect open, for closed frames this time of year will toast the plants. Assuming they are open there should be no problem with self-pollination. However, temperature may play a part here. Flowering and fruit set in tomato is best at day temperatures between 70°F and 85°F and night temperatures between 60°F and 70°F. At day temperatures above 90°F set will be decreased, and above 105°F will not occur at all. Also, warm nights promote vegetative growth at the expense of fruit growth. Since your plants are in an enclosed space pay particular attention to temperatures and try to keep them cooler. After the fruit have set the optimum temperature for their maturation and coloring is 70°F to 75°F. The bottom line here is that your frames may be too hot in summer for best tomato growth unless you have taken steps to keep them cool. Finally, depending upon cultivar, tomatoes require from 35 to 60 days after set to ripen. That means that with even the very earliest cultivars, in order to have ripe fruit by early August the plants would have had to set fruit by early July at the latest. I wish you good luck with your crop and applaud you for having a garden.
Aspen Suckers, Onions and Rhubarb Bolting, Cherry-Plums
Q
Can I spray the aspen shoots coming up in my driveway or will it kill the aspen tree?
My onions and rhubarb are bolting. Do I pinch off the flower heads? Someone said that rhubarb bolts early when it needs to be fed. Is that true?
My cherry plum tree blooms and blooms, but no fruit. It is not supposed to need a polinator, any ideas why no fruit?
A
You can spray the aspen suckers in your driveway as long as you use a contact herbicide, which will kill only the tissue it contacts. A systemic herbicide such as glyphosate or 2,4-D is taken into the tree’s vascular system and could damage the mother plant as well as the suckers.
Onions and rhubarb can throw seed stalks this time of year as a response to daylength and prior chilling. Seed set on either of these plants will utilize nutrients that might otherwise be put into bulb and petiole formation. You are correct to pinch off the flowers on onions, but leave the stalk. Cut out the entire flower stalk on rhubarb. Rhubarb bolting has little to do with insufficient fertilizer directly, but crowded plants are more apt to throw seed stalks.
Cherry-plums are a mixed bag of surprises. The true cherry-plums, sometimes called plum-cherries, are hybrids between native plums and Prunus besseyi or between the Japanese plums and P. besseyi. Unfortunately, the term "cherry-plum" is also sometimes applied to the bush cherries and that confuses the issue. The true cherry-plums are very hardy, drought-resistant, bloom late (making spring frosts less of a worry), come into bearing early, hold their fruit well, and ripen them relatively early in the season. They are considered better flavored than the native plums. However, they are generally short-lived (about 10 years), poor pollen producers, self-sterile, and produce small fruit that does not keep well. The hardiest varieties include 'Compass' and 'Opata'. Because they are self-sterile you should plant at least two varieties to provide adequate cross-pollination.
Pear Trees
Q
I highly appreciate your recent column on fruit trees in Zone 4 magazine. I wonder if you might be able to suggest sources for the pear varieties you suggest in the article, as I have not been able to locate them at local nurseries?
My backyard is not large, and my wish is to form a pear arbor with two trees. Doing so is my best hope to fit them in the space I have. As an in-town resident I think I can push the envelope a bit from what is trustworthy in more rural areas.
Thanks for sharing your knowledge!
A
It’s always better to purchase trees from a locally owned nursery. While pear varieties can be even more cold hardy than apple varieties, the trees are not usually planted in our area because of the tremendous fire blight problems they encounter. That’s likely why you are having so much trouble finding them for sale locally. First, ask the staff at your local nursery if they can order pear trees for you. If they can’t then place your order with one of the many mail order nurseries offering them for sale. Here are only a few of the many nurseries carrying pear trees.
St. Lawrence Nurseries. www.sln.potsdam.ny.us
Stark Bro’s. starkbros.com
Nature Hills Nurseries. naturehills.com
Borage
Q
My young borage transplants continue to die in their peat pots before I set them into the garden. I understand borage is easy to grow and has insect-repellent properties, but it doesn’t grow for me. What am I doing wrong?
A
Borage (Borago officinalis) is generally considered easy to grow, doing best in warm, well-drained soil. The plant is a hardy annual and should do very well for you in the garden. It will self-seed, so be careful that you keep it under control by pinching off most of the seed heads. It requires very little fertilizer but needs plenty of room, so plant it a few feet away from other plants.
I do not understand why you are having so much trouble growing the transplants. Perhaps the peat pots and media are too wet? Perhaps you are fertilizing too much? Perhaps you have a soil borne disease problem? Try sowing the seeds directly into the garden in soil well-prepared with organic matter. As for the insect-repellent properties attributed to the plant, my suspicion is that that information is anectdotal only. Believe it if you wish. I know that bees simply love the flowers on our borage.
Lawn Fertilizer
Q
My lawn is a mess. I don’t want to make the grass grow so fast I spend all summer behind the lawnmower, but I do want to get rid of the weeds and make the grass stronger.
A
Lawn grass may not need fertilizer to grow, but it will need fertilizer to grow well. You did not specify what sort of lawn you have, but most of us have lawns that are mixes of Kentucky bluegrass and fine fescue, both cool-season grasses that do fairly well in our region. The more healthy we maintain our lawn grasses, the less apt the lawn is to become infested with dandelions, creeping bentgrass, plantain, and other weeds. Weeds are opportunists and when our preferred grasses are weak, weeds make themselves right at home in the front lawn.
A very high maintenance lawn fertilizer schedule that will have your lawn approaching the look of the one on the seed package requires application of about 5 to 6 pounds of actual nitrogen per 1000 square feet per year. A medium maintenance schedule, which most of us prefer, requires application of about 3 pounds of nitrogen per 1000 square feet of lawn per year. A light maintenance schedule requires application of about 1 to 2 pounds of nitrogen per 1000 square feet per year and in my opinion is not worth the time you put into it. Since you should apply only about 1 pound of nitrogen per application, a high maintenance schedule requires about five applications per year, the first in early spring when the ground has thawed, the second around Memorial Day (or after you have cut the lawn twice), the third in mid-summer (provided you irrigate), the fourth around Labor Day (or after the high heat of summer has passed), and the fifth around Columbus Day (or about one month before the soil freezes for the winter.)
If you practice a medium maintenance schedule, fertilize around Memorial Day, Labor Day, and Columbus Day.
All fertilizer bags have three numbers on them, called the analysis. For example, 25-10-10. The first number is the percentage of nitrogen the fertilzer contains, the second and third the percentages of the oxides of phosphorus and potassium respectively. Here’s the trick to figure how much fertilizer to apply per 1000 square feet to provide 1 pound of actual nitrogen. Our example fertilizer is 25% nitrogen, so you will need 4 pounds of the fertilizer to provide 1 pound of actual (100%) nitrogen: 100/25 = 4. Apply 4 pounds of the fertilizer per 1000 square feet each time you fertilize the lawn. If our fertilizer had 20% nitrogen you would have to apply 100/20 = 5 pounds per 1000 square feet.
Manure
Q
Can I apply fresh rabbit manure and horse manure to my garden in spring? Do they contain weed seeds?
A
Both rabbit manure and horse manure can be used in the vegetable garden to good effect.
Manure nutrient analysis varies by the type of animal and feed, the amount of bedding it contains, and the way it was handled prior to spreading on the soil. This said, the proximate analysis of fresh horse manure is 0.7-0.3-0.5 while that of fresh rabbit manure is 2.0-1.3-1.2. Rabbit manure is considered a "hot" manure in part because of its relatively high nitrogen content and when used fresh can damage young plants. All fresh manures potentially contain weed seeds that can cause problems in the garden although rabbit manure will likely contain far fewer than horse given the animals’ diets. In my experience horse manure is particularly weedy. Composting the manure before you apply it can reduce the weed seed content substantially and you will be better off for doing it. Spring-applied manure should always be composted first. Fresh manure can be applied in the fall, plowed in, and allowed to rot over the winter but you may still find some weeds coming up in the spring from that fresh manure. Beware that old manure piles may be infiltrated with quackgrass rhizomes which are very difficult to be rid of regardless of whether or not it has been composted. Those old piles may also have high salt content and the manure in them may not be suitable for your garden. Bottom line-composted manure is always safer to use than fresh manure.
