Many of our estimates come from an extension page we’ve read that gets close without pinning the number down. Others are still our own best guess, and on some the sources disagree. Treat them all as a starting point.
Hardiness zone — an estimate
How far the roots reach past the canopy — an estimate
Mature spread — an estimate
Dwarf plum: mature height — an estimate
Dwarf plum: mature spread — an estimate
Soil pH (in water) — an estimate
Frost tolerance — an estimate
Mature height — an estimate
Rules that apply to plum
Don't follow a Verticillium host with raspberries, strawberries or stone fruit Promising
Don't follow a Verticillium host with raspberries, strawberries or stone fruit
If you skip this, you lose real yield. The planner warns you.
How it works: Verticillium dahliae persists in soil as microsclerotia and infects a wide host range spanning nightshades and rose family. There is no in-ground cure once a susceptible perennial is planted, so it can wilt and die from inoculum an earlier host left behind. Because the reservoir family may differ from the victim's, the same-family rotation intervals miss it.
Evidence: checked against 3 sources in the research-based literature.
Verticillium wilt is caused by two common soilborne fungi (Verticillium dahliae and Verticillium albo-atrum) that have a wide host range
www.umass.edu
Brambles - DiseasesUMass Extension, New England Small Fruit Management Guide
Verticillium attacks a wide range of plants, including potatoes, tomatoes, peppers, eggplant and strawberries. It overwinters in the soil and on plant debris. Do not plant [raspberries following these crops].
Verticillium Wilt of Tomato and Eggplant NC State Extension
Verticillium Wilt of Tomato and Eggplant
Remedy
Site the perennial on ground with no recent nightshades, or choose one that is not Verticillium-susceptible. Extension advises growing a non-host (corn or a small grain) for at least two years first, without claiming that clears the soil. Once the perennial is planted there is no in-ground cure.
If you skip this, you lose real yield. The planner warns you.
How it works: The same soil reservoir as the wilt rule for ground that grew the tomato family (Verticillium dahliae microsclerotia). This rule adds the gardener's own record: a logged strawberry, raspberry or other bramble, or stone fruit counts as an earlier host, while a rose family that is not a host, like apple, does not.
Evidence: checked against 2 sources in the research-based literature.
To minimize ... disease, choose a planting site with no known history of this problem. Avoid land recently planted with tomatoes, potatoes, eggplants, peppers, strawberries, raspberries, or stone fruits
www.umass.edu
Brambles - DiseasesUMass Extension, New England Small Fruit Management Guide
Verticillium attacks a wide range of plants, including potatoes, tomatoes, peppers, eggplant and strawberries.
Plus one working note on how the sources were read.
Remedy
Site the perennial where the log shows no previous Verticillium host, or choose one that is not susceptible. Extension advises growing a non-host (corn or a small grain) for at least two years first, without claiming that clears the soil. Once the perennial is planted there is no in-ground cure.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: Zones encode average annual minimum winter temperature, which governs whether a woody perennial survives to spring. It is the wrong quantity for an annual, which never sees winter.
A zone that is too warm is a second, different mechanism. Mild winters do not kill a perennial; they fail to chill it. Deciduous fruit crops need a winter dormancy period to break bud and set fruit, so in a zone milder than a plant is adapted to it may survive and never crop. Only the cold end is enforced, because only winter survival follows from what a zone measures; the warm end gets advice and is never refused.
That warm limit is a property of the cultivar, and that limits what this rule can do. Chill requirement is published per variety and varies enormously within a species, so a species-level ceiling says "the modeled range does not reach your zone", never "no plant of this kind will crop for you". So above its range the planner still offers the plant, with advice to choose a cultivar rated for your zone.
Evidence: checked against 1 source in the research-based literature.
Winter cold-hardy cultivars adapted to the colder regions of Oregon (such as zones 5 to 7), may not grow normally in regions of the Willamette Valley (zone 8) where winters are warmer and plants receive less winter chill.
Plus 2 working notes on how the sources were read.
Every stone fruit shares brown rot, and it overwinters on the tree. Strip the mummies and prune the cankers before bud break, and keep fallen fruit picked up. Promising
Every stone fruit shares brown rot, and it overwinters on the tree. Strip the mummies and prune the cankers before bud break, and keep fallen fruit picked up.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: Monilinia fructicola overwinters in mummified fruit left on the tree or the ground and in twig cankers; at bloom its spores blow and splash to blossoms, and infected fruit sheds spores that spread to other fruit on the same tree and to neighboring trees, wild Prunus included.
Evidence: checked against 3 sources in the research-based literature.
Brown rot is a destructive fungal disease of trees and shrubs in the genus Prunus, which includes peaches, plum, cherries, apricots and nectarines
Remedy
Before bud break, remove every shriveled fruit still on the tree and cut out cankered twigs. Pick up fallen fruit through the summer, thin so fruit do not touch, and prune for air. Remove wild or volunteer Prunus nearby.
A young apple or stone-fruit tree planted where an old one of its kind stood tends to sulk (stunted, uneven, sometimes dying back), because the ground an orchard tree leaves behind is not neutral for the next tree of the same kind. A good hunch
A young apple or stone-fruit tree planted where an old one of its kind stood tends to sulk (stunted, uneven, sometimes dying back), because the ground an orchard tree leaves behind is not neutral for the next tree of the same kind.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: Apple leaves behind a soil complex of fungi and oomycetes (Rhizoctonia, Ilyonectria, Phytophthora, Pythium) together with the lesion nematode Pratylenchus penetrans; the stone fruits leave the genus-wide version, Prunus replant disease, and in peach the ring nematode with the bacterial- canker organism drives its severe named form, Peach Tree Short Life. Either way a young tree of the same kind meets that loaded soil with a root system too small to outgrow it.
Evidence: checked against 5 sources in the research-based literature.
In Washington State, the disease is caused by multiple species within several genera of fungi: Rhizoctonia, Ilyonectria; oomycetes: Phytophthora, Pythium and in some sites lesion nematode Pratylenchus penetrans
Successive orchard plantings of almond and other Prunus species exhibit reduced growth and yield in many California soils. This phenomenon, known as Prunus replant disease (PRD), can be prevented by preplant soil fumigation or anaerobic soil disinfestation, but its etiology is poorly understood
Remedy
On old orchard ground, don't drop a new tree of the same kind into the same spot. Have the soil tested for nematodes first; choose a replant-tolerant rootstock where one exists (a Geneva-series apple, a 'Guardian' peach); set the tree in the old grassed row-middles, away from the old tree row; or replace the soil in the planting hole. Waiting alone is not treated as a cure. Many other crops host the same organisms, so a rotation is at best partial and never a guarantee.
Tree fruits differ in whether a lone tree can set a crop. Apples and most European pears are self-unfruitful. One cultivar alone will not set a normal crop, so plant at least two different cultivars whose bloom periods overlap. For apple, a flowering crabapple in bloom at the same time also works. European plums are partially to entirely self-fruitful, and a second European plum cultivar makes fruit set reliable. Japanese and hybrid plums will not cross-pollinate them. Peaches and sour cherries are self-fruitful and may be planted alone. Partner trees must stand near each other. The published distances are within 50 to 100 feet, and 300 feet at most. Promising
Tree fruits differ in whether a lone tree can set a crop. Apples and most European pears are self-unfruitful. One cultivar alone will not set a normal crop, so plant at least two different cultivars whose bloom periods overlap. For apple, a flowering crabapple in bloom at the same time also works. European plums are partially to entirely self-fruitful, and a second European plum cultivar makes fruit set reliable. Japanese and hybrid plums will not cross-pollinate them. Peaches and sour cherries are self-fruitful and may be planted alone. Partner trees must stand near each other. The published distances are within 50 to 100 feet, and 300 feet at most.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: A self-unfruitful tree will not set a normal crop from its own pollen or the pollen of another tree of the same cultivar; it needs pollen from a genetically different, compatible cultivar, carried by bees while both trees are in bloom. That is why the partner must be a different cultivar, must bloom at the same time, and must stand within a bee's working range. It is also why a self-fruitful species like peach or sour cherry, whose own pollen sets fruit, bears alone.
Evidence: checked against 3 sources in the research-based literature.
Apple: Cross-pollination is always needed to produce adequate fruit crop
Remedy
Check the pollination requirement before buying. For apple and pear, plant two different cultivars with overlapping bloom. Early- and late-blooming cultivars may miss each other, and for apple a flowering crabapple that blooms at the same time also serves. For European plum, pair with a second European plum cultivar. A Japanese or hybrid plum won't do. Site partner trees close together, within 50 to 100 feet where you can and within 300 feet at most. A peach or sour cherry needs no partner.
If you skip this, the planting fails. The planner warns you.
How it works: On a clear, still night leaves lose heat to the open sky, so a leaf can fall to freezing and ice can form in it while the thermometer, a couple of meters up, still reads a few degrees above.
Evidence: checked against 7 sources in the research-based literature.
Frost occurs when air is warmer than 32°F but plant tissues drop to 32°F or below because plants radiate (lose) heat into the atmosphere, especially during cool, clear nights.
Radiation frosts occur on calm clear nights that lack cloud cover to hold in heat.
Remedy
The evening before, cover the crops at risk with a sheet or frost cloth, never plastic, reaching the ground and loose at the bottom so the soil's warmth can rise under it, and take it off in the morning. A cover helps least in a long, hard freeze.
If you skip this, it still grows, just less well. The planner suggests it.
How it works: Soil warmed by the sun by day is the heat source at night; a covering low to the ground traps that heat around the plants on calm, clear nights, keeping them a few degrees above the open air through the light frosts at each end of the season.
Evidence: checked against 6 sources in the research-based literature.
The ground and frame of the cold frame are heated by the sun during the day and radiate that heat during the night, keeping the inside warmer. They are used to extend the growing season by two to four weeks in both the fall and the spring, allowing you to start plants outdoors earlier and continue growing them later in the season.
In trials in Fort Collins, Colorado, a plastic cover on a frame typically provides 3°F to over 6°F of frost protection. It works well for cool season crops that are somewhat tolerant of frosty nights and adds two to six weeks or more on both ends of the growing season.
Soil warmed by the sun in the daytime, is the source of heat for frost protection at night. Moist, smooth soil absorbs more heat. To trap heat from the soil around young vegetables at night, place a covering that is low to the ground and spreading. To recharge the heat source for the next night, any covering must allow sunlight to shine through to the soil or must be removed in the daytime.
Low = Plant 1–2 weeks before suggested planting date; Medium = 2–4 weeks before suggested planting date; High = 4–8 weeks before average planting date
hort.extension.wisc.edu
Floating Row CoverUniversity of Wisconsin-Madison Extension, Wisconsin Horticulture, Susan Mahr
Depending on the weight of the covering you choose, you can gain between 2 and 8 degrees of frost protection or warm the local environment sufficiently to harvest certain crops a week or two early.
Clear plastic is useless in providing frost protection because the radiant energy released from the soil on those frosty nights passes right through the covering and never warms the air around the plants.
Remedy
Sow or set out cool-season crops under the cover that many weeks ahead of the open-ground date, and keep autumn crops covered past the usual last call. Vent on sunny days, keep plastic off the leaves, and close the cover before sunset.
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
