Fielding Questions: Planting potatoes in a barrel, rabbit-proof plants, tomato blossom end rot
This week, gardening columnist Don Kinzler fields questions about planting potatoes, rabbit-resistant shrubs, and how to prevent tomato blossom end rot.
Q: Forty years ago there was an old timer who was growing potatoes in a barrel. It had holes in the side for the leaves and the spuds were in layers, but I don't remember how it turned out. Have you ever heard of this before? This old timer would like to try it. – Russ W.
A: Growing potatoes in barrels is making a comeback because it doesn’t require much space. I’m curious to try this myself because there are reported yields of 50 to 100 lbs. from one 55-gallon barrel.
One might think the method involves plants growing out of holes in the barrel’s sides, but in the most common method, seed potato pieces are planted near the bottom of the barrel, and soil is added as the plants grow, forming tubers all along the stems, while the plants grow upward.
Those who have tried this successfully recommend using a food-grade or well-cleaned 55-gallon plastic barrel with bottom drain holes drilled, and placed in full sun. Use well-drained potting mix designed for containers rather than garden soil.
Fill the bottom of the barrel with about six inches of potting mix. Place seed potato pieces on the mix, spaced six inches apart. Cover with six inches of potting mix and water well.
When the potato plants have grown six inches tall, cover with more potting mix, leaving just an inch or two of leaves exposed. Water, and keep moist, but not soggy.
Repeat the process periodically until you reach the top of the barrel. Continue to grow until the foliage dies in fall. Then tip the barrel over and harvest your potatoes.
Q: You’ve mentioned plants that rabbits like, of which I have many. What shrubs can I plant that rabbits won’t eat to the ground? Glenn M.
A: I hesitate to recommend rabbit-resistant plant lists, because when I search for such lists, they often contain plants that have been devoured in our own yard. For example, Pennsylvania State University’s rabbit-resistant list includes spirea, viburnum, hydrangea, lilac, cotoneaster and clematis, and all have been consumed by rabbits in the Kinzler yard, which casts doubt on the entire list. When rabbits are winter-hungry, they’ll feed on almost any tree or shrub.
At one time or another, rabbits have fed on nearly everything I’ve planted, with the possible exception of potentilla shrubs. That’s why I hesitate to make recommendations about rabbit-free plants. Instead, I rely on fencing and frequent application of repellents. I wish I had a better answer for you, Glenn.
Q: In a recent article you said North Dakota soils contain plenty of calcium. If so, why do you say a lack of calcium causes blossom end rot in tomatoes ? I've been raising tomatoes for 50 years, and it’s my experience that bottom rot is caused by uneven watering. The tomato plant itself takes the moisture back from the tomato fruit, causing bottom rot. Watering directly to the plant by dripline is a great preventative. – Al S.
A: Thanks for asking for clarification. It sounds contradictory, but tomato plants can be starved for calcium even though they’re growing in calcium-rich soil because the plants can’t always access it. The plant then sucks calcium from the bottom of the developing fruit, causing the blossom end rot that is so common.
Al, to your very good point, uneven soil moisture is a key factor because dry soil prevents calcium from liquefying enough for tomato roots to drink it in. To liquefy the calcium, a uniform supply of moisture is needed.
Past research showed the interplay between soil moisture and calcium is a main trigger. Even if tomato plants are kept uniformly watered it won’t prevent blossom end rot if there’s not enough calcium in the soil. Where natural soil calcium is lacking other regions of the country add calcium-rich lime to their garden soil.
To prevent blossom end rot, choose cultivars less prone to the disorder and keep soil moisture uniform, as you’re doing, Al, and mulch tomato plants in late June after soil has warmed.
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.