Plastic is the key to growing watermelons in North Dakota
"Fielding Questions" columnist Don Kinzler also says it's important to be patient with asparagus and offers advice to a reader about an apple tree that isn't producing fruit.
Q: Can you remind us what you put on top of your soil to make your watermelons grow so well? Is it some sort of mulch? — Cassie L.
A: Pioneering research was conducted at North Dakota State University’s Horticulture Department by Dr. Earl Scholz in the 1970s to determine ways to speed production of muskmelons and watermelons in North Dakota. These crops typically require long, warm growing seasons. Melons, if they ripened at all, would be extremely late or nonexistent under North Dakota’s usual planting conditions.
NDSU researchers discovered that clear plastic mulch, when laid in contact with the soil, hastened the growth of melons by warming soil temperatures, speeding the plants enough to ripen well within our growing season. Clear plastic creates a greenhouse solar effect over the soil, capturing heat more effectively than black plastic, which doesn’t transmit the heat as effectively to the cool darkness below.
To use clear plastic mulch, cut rolls of-4 mil plastic into 4-foot-wide sections and the length of your row. Lay the edges in shallow trenches and cover with soil to hold securely. Plastic can be laid down in early May to warm the soil before a projected planting date for melons of May 25.
Muskmelon and watermelon harvest can be given a further boost by starting plants indoors May 1. Seed directly into peat pots, or other containers. When transplanting into the garden, cut X-shaped slits in the plastic, plant the seedlings and seal the edges with soil. Water percolates into the plastic through the planting holes.
Select melon types that list a maturity of 70 to 85 days. Melons requiring 90 to 100 days are extremely late. By selecting the right varieties, and planting pre-started transplants into clear plastic mulch, home gardeners can enjoy delicious watermelons and muskmelons.
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Q: We have a 5-year-old apple tree that hasn’t produced fruit, although it’s a nice, healthy tree. We have heard things like taking a bat to it! What are your thoughts on that? — Laurie S.
A: I've also heard the old tales about beating apple trees with chains or baseball bats — and there's absolutely no truth to such practices, which can cause irreversible damage to a tree. Anyone who claims this works is lucky they didn't kill the tree, and if their tree produced fruit afterwards, it was in spite of what they did, not because of it.
Apple trees normally bear fruit three to seven years after planting, with five years being a rough average. Some varieties take longer than others. Types like Haralson have been known to take seven to nine years. Your 5-year-old apple tree is probably on the verge of flowering and fruiting over the next year or two.
Fruiting of apples can be delayed if the tree is receiving too much nitrogen fertilizer from the lawn, which tends to keep young apple trees in the non-fruiting, juvenile stage. When fertilizing the lawn, steer clear of the apple tree's rootzone. Different rules are used to determine a root system’s lateral spread outward from the trunk, and a common rule is at least one and a half times the tree's height, or more, meaning a 10-foot-high tree has roots spreading outward 15 feet from the trunk.
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Q: I planted asparagus from bare-root plants last year, and let it grow though the whole season. Can I start harvesting it this spring? — Dan M.
A: Asparagus can last for many decades, but it takes a little patience at the front end. For best results, allow asparagus to grow for two full growing seasons before harvesting lightly the third year. Delaying harvest allows the root system to develop fully.
By the third year, asparagus stalks increase in diameter, progressing from the small, skinny spears of earlier seasons. In following years, stop asparagus harvest on July 4, and let the fernlike tops remain through fall and winter, cutting them back in early spring before new shoots appear.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at firstname.lastname@example.org. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.