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Growing Herbs at High Altitude
Susan Fernalld, Mountain Master Gardener
Gardeners like to grow herbs for their beauty, fragrance, and seasoning
in cooking. How does one grow herbs at high altitude (over 7500
feet) where the growing season is shortened, temperatures are cooler,
and water is scarcer?
Moisture and soil factors
Mountain soils naturally provide good drainage, a plus for growing
herbs. As plants go, herbs have "low to average" water needs, but
in our arid environment this may mean herbs need supplemental water
to survive. Tips on growing these
without using well water include: direct downspout drainage
to disperse via soaker hoses through your garden. Add organic material
such as manure or compost to rocky soil to retain moisture longer.
Mulch around plants to slow evaporation.
Short season strategies
To compensate for the shorter growing season in the high country,
start perennials from young plants in early summer. Some perennial
herbs that aren't hardy in our high altitude USDA hardiness zones
(3-4) are grown as annuals, or we grow them in containers and bring
them inside to over-winter. Start annuals from seed in early summer.
Alternatively, sow them in a cold frame in the fall to take advantage
of the greater natural precipitation during fall and winter. Seedlings
will emerge the following spring ready to be thinned and eventually
transplanted into the warm garden. Most herbs need six hours of
sun after 10 o'clock daily. Some, such as basil, rosemary, and dill,
need protection from drying winds. Find sheltered spots for them
in the garden, or grow them in containers that can be moved around
according to the conditions.
Prevent invasiveness
To keep non-native herbs corralled, prevent self-seeding by trimming
back annuals when flowers are beginning to fade. Border perennials
with deep edging, or keep their roots from spreading too far afield
by planting them in five-gallon nursery containers (bottoms cut
off) sunk into the ground.
Harvesting and preserving.
Harvest herbs in the morning after the dew is off the plant and
essential oils are at their highest concentrations. Hang herb bundles
in a cool, dry place. Remove the completely dry foliage or seed
and store in labeled, airtight and dark containers. Dried herbs
store well up to a year.
Selected herbs. (Adapted from Fact sheet 9.335
by P. Kendall)
| Herb |
Characteristics |
Growing |
| Basil (Ocimum basilicum) |
Tender annual. Grown in several varieties
for leaves with different flavors. Attractive to bees and butterflies. |
Plant seeds in well-drained, medium-rich soil.
Likes sunny, sheltered spot. Space mature plants 12 inches apart.
Plant in rich soil and clip to first pair of leaves from base.
May be grown in containers inside and out. |
| Chervil (Anthriscus cerefolium) |
Annual. Resembles a fine-leaved parsley and
fennel combined. Leaves have a light licorice, peppery flavor.
|
Plant seeds in shade or part shade. Avoid
transplanting. Thin plants to 9 inches apart. May be grown in
containers indoors or out. |
| Chives (Allium schoenoprasum) |
Native perennial (USDA Zone 3). Flowers in
early summer. Similar to green onion, but milder and finer leaves.
Don’t grow Garlic Chives (Allium tuberosum) which can
be invasive. |
Plant bulbs or starter clumps in light, medium-rich
soil in sunny place. Cut flower stalks to the ground after blooming.
Thin clumps every third spring. Space mature plants 5 inches
apart. Transfer some clumps to grow in containers indoors or
out. |
| Dill (Anethum graveolens) |
Annual. Feathery foliage, flower umbels. Grows
2-3 feet tall. Grown for both foliage and seed, although it
may not have time to form seed at high altitude. Attractive
to bees and butterflies. |
Plant seeds in medium-rich, sandy, well-drained
soil in sun. Needs wind protection. Avoid transplanting. Thin
seedlings to 12 inches apart. Stake when 18 inches tall. Do
not plant near fennel or they may cross-pollinate. May self-seed. |
| Fennel (Foeniculum vulgare) |
Annual. At high altitude grow it for the leaves
with their slightly anise taste. Flowers appear toward fall.
Attractive to bees and butterflies. |
Plant seed in well-drained soil in sunny spot.
Thin seedlings to 2 feet apart. Makes a good container plant
indoors or out when kept trimmed to 12 inches. |
| Marjoram, sweet (Origanum majorana) |
Perennial (USDA Zone 7) treated as an annual
since it is not hardy in our Zones 3-4. Small bush with white
flowers. Gray-green leaves with slightly bitter undertone. Attractive
to bees, butterflies, and birds. |
Plant in medium-rich soil. Requires shade
until well started, then full sun. Space mature plants 8-10
inches apart. May be grown in containers and brought indoors
to overwinter. |
Mint (Mentha piperita ‘Chocolate,’
‘Peppermint,’ and ‘Lavender’
and native Monarda fistulosa
|
Perennial. (Varieties listed here are
hardy to USDA Zone 3.) Grown for leaves. Refreshing odor and
flavor. Attractive to bees and butterflies. Deer avoid it. Nepeta
cataria (catmint) is hardy here as well. |
Plant seedlings in rich, moist soil.
To prevent invasiveness, do not allow it to go to seed. (Cut
back plant severely as flowers begin to fade). Can be grown
in containers indoors as well. |
| Oregano (Oreganum vulgare) |
Perennial (USDA Zone 5) treated as an
annual since it is not hardy in our Zones 3-4. Grown for leaves.
Flavor similar to sweet marjoram, but stronger and more sage-like.
|
Plant in light, well-drained soil in
full sun. Shelter from cold winds. Space mature plants 12 inches
apart. Can be grown in containers indoors or out if roots given
enough room. |
| Parsley (Petroselinum crispum) |
Annual. Grown for finely curled, aromatic
leaves. Attractive to bees and butterflies. |
Plant in medium-rich soil in sun or
part shade. Seeds best started in cold frame or window box.
Space mature plants 6-8 inches. Good in pots indoors or out
if roots given enough room. Keep leaves producing by never allowing
plant to flower. |
| Rosemary (Rosmarinus officinalis) |
Perennial (USDA Zone 7) treated as an
annual since it is not hardy in our Zones 3-4. Pine-like bush
in mint family. Pale blue flowers. Leaves have a spicy odor
and warm, piney flavor. Attractive to bees and butterflies.
|
Plant seedlings one each in containers
using well-drained soil. Place in a sunny, sheltered spot. Bring
inside in the winter and place in a bright sunny window. |
| Sage (Salvia officinalis) |
Perennial (USDA Zone 5). Grown for leaves.
Don't use Western U.S. varieties (Artemisia spp), as these taste
like turpentine. Attractive to bees and butterflies. |
Plant small plants in well-drained soil
in full sun. Can be grown in containers indoors or out in full
sun. Can be brought inside as a houseplant in a sunny window
to overwinter. |
| Summer savory (Satureja hortensis) |
Annual. Bushy plant with long, narrow
leaves and weak, woody stems. Use only young leaves. Attractive
to bees. |
Plant in medium-rich soil in sun. Thin
seedlings to 6 inches apart. Can be grown in containers indoors
or out. |
| Tarragon (Artemisia dracunculus) |
Perennial (USDA Zone 4). Slender, dark
green leaves with sweet anise scent. Considered essential in
many French dishes. |
Plant in well-drained soil in full sun.
Propagate by root divisions. Space mature plants 3 feet apart.
Subdivide every three years. Can be grown in containers indoors
or out if roots given enough room. Does not like wet feet. |
| Thyme (Thymus vulgaris) |
Perennial (USDA Zone 4). Small shrub
with tiny, brownish-green leaves. The leaves have unexcelled
aroma and flavor. Attractive to bees and butterflies. |
Plant small plants in well-drained soil
in full sun. Clip back each spring. Space mature plants 10 inches
apart. May be grown in containers indoors and out. |
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