Mountain gardening means growing where the season is short, nights are cold even in summer, and the ground often slopes. Gardens at altitude face late spring frosts, early autumn frosts, strong sun, drying wind, and thin, rocky soil — yet mountain gardens can be wonderfully productive, with crisp vegetables, hardy flowers and fruit that tastes better for the cool nights.
The key is to accept the mountain climate instead of fighting it. Choose short-season and cold-hardy crops, start seeds indoors, protect plants from frost, terrace slopes so soil and water stay put, and build soil with compost every year. A mountain gardener who plans around frost dates and picks the right varieties will harvest well, while a gardener who plants tender crops too early will lose them. Before you plan, check your local extension service for your local frost dates and recommended varieties.
The mountain climate: frost, sun and wind
The defining feature of mountain gardening is the short frost-free season — often only a few months between the last spring frost and the first autumn frost. Nights can be cold even in midsummer, and a clear night can bring frost when the day was warm. Sun is stronger at altitude, so plants can scorch even on a cool day, and wind dries soil and damages stems. Cold air also sinks, so low spots and valley bottoms are frost pockets where cold air collects, while a slope a few metres higher can be several degrees warmer. Walk your garden on a cold morning and notice where frost lingers longest — that is where tender plants should not go. Our frost cloth and cold frames guides explain the main protection methods, and your local extension service can give you frost dates for your elevation, which matter more than any general planting calendar.
Short-season and cold-hardy crops
Choose crops that mature quickly and tolerate cold. Leafy greens such as lettuce, spinach, kale and chard grow well in cool mountain summers — see growing lettuce, growing kale and growing spinach. Root crops such as carrots, beets, turnips and radishes thrive in cool soil; see growing carrots and growing beets. Peas, broad beans and brassicas such as cabbage, broccoli and Brussels sprouts are all cold-hardy — see growing cabbage and growing broccoli. Potatoes do well in mountain gardens and store through winter. For tender crops such as tomatoes, peppers and squash, choose the earliest varieties you can find, start them indoors, and grow them in the warmest, most sheltered spot, or in a greenhouse or cold frame. Fruit choices include currants, gooseberries, raspberries and hardy apples, which all tolerate cold winters well.
Starting seeds indoors and using protection
In a short season, starting seeds indoors buys you weeks. Sow tomatoes, peppers, squash and brassicas indoors four to six weeks before the last expected frost, in a bright windowsill or under grow lights, and harden them off gradually before planting out — a few hours outside each day, building up over a week. Use cloches, cold frames and row covers to protect young plants and to warm the soil before planting; our cloches for plants and row covers guides explain how. Cover plants with frost cloth on cold nights, and remove it in the morning so they do not overheat. A simple cold frame can extend the season by weeks at each end, letting you sow salad leaves early and keep them going late. Water in the morning so plants are not wet overnight, and mulch after the soil has warmed in late spring — mulching too early keeps cold soil cold.
Terracing and gardening on a slope
Slopes are the other great mountain challenge: rain runs off, soil washes downhill, and working on a slope is hard. Terracing solves all three. Build low retaining walls of stone or timber across the slope, level the ground behind each wall, and you create flat beds that hold soil and water. Stone walls also store heat from the day and release it at night, which helps tender plants. If full terracing is too much work, use contour beds — beds that follow the contour of the slope — with a small ridge on the downhill edge to catch water. Plant ground cover on steep banks you do not want to terrace, and never leave a slope bare over winter, or the soil will wash away. Raised beds work well on slopes too, because you can level each bed individually; use the soil volume calculator to work out how much soil each bed needs. Always work across a slope, not up and down it, and take care on wet ground.
Building thin mountain soil
Mountain soil is often thin, stony and low in organic matter. The answer, as always, is compost — added every year, in generous amounts. Clear stones from planting beds, but do not try to remove every stone from the whole garden; use them for walls and paths instead. Dig compost into beds before planting, mulch after planting, and grow a cover crop such as clover or phacelia on any bed that is resting — see our cover cropping guide. Raised beds filled with a mix of topsoil and compost give you good soil quickly where the natural soil is too thin to work. Test your soil pH too, because mountain soils can be acidic or alkaline depending on the rock beneath; our soil pH testing guide explains how. Do not add large amounts of fertiliser to thin soil in the hope of a quick fix — it washes away, and steady compost is better. Over a few years, compost, mulch and cover crops will turn thin mountain soil into dark, workable ground.
Flowers and perennials for mountain gardens
Mountain gardens suit hardy perennials and alpine plants that evolved for these conditions. Asters, coneflowers, lupins, delphiniums and daylilies all cope with cold winters and flower well in cool summers. Alpine plants such as saxifrage, aubrieta, sedum and sempervivum thrive in rocky, well-drained soil and need little care — plant them in a rock garden or a stone wall. Lavender and rosemary grow in sunny, sheltered mountain spots, though they need good drainage and may need winter protection at higher elevations. Spring bulbs such as daffodils, tulips and crocus flower reliably after a cold winter, which they need to bloom well. Avoid tender perennials that need a long, warm season, and avoid planting anything that needs constant watering, because mountain wind dries soil quickly. A mountain flower garden, planted with hardy species and mulched well, can look after itself for years.
Common mistakes to avoid
The biggest mistake is planting tender crops outdoors before the last frost, which kills them overnight. The second is ignoring frost pockets — planting tomatoes in the lowest, coldest part of the garden instead of the warmest slope. The third is mulching too early in spring, which keeps the soil cold and delays growth; wait until the soil has warmed. The fourth is leaving slopes bare, so rain washes the soil away. The fifth is choosing long-season varieties that never ripen before the first autumn frost — always pick the earliest varieties you can find. The sixth is under-watering in wind: mountain wind dries soil fast, so check moisture regularly even when the air feels cool. Finally, do not expect a mountain garden to match a lowland one plant for plant — grow what suits the mountain, and check your local extension service for varieties that are proven at your elevation.
Frequently asked questions
When should I plant in a mountain garden?
Plant cold-hardy crops such as peas, lettuce, kale and radishes as soon as the soil can be worked in spring. Wait until after the last expected frost for tender crops such as tomatoes, peppers and squash, and start those indoors first. Your local extension service can give you frost dates for your elevation, which are more useful than any general calendar.
What vegetables grow best at high altitude?
Cold-hardy, short-season crops: lettuce, spinach, kale, chard, carrots, beets, turnips, radishes, peas, broad beans, cabbage, broccoli, Brussels sprouts and potatoes. Tender crops need the earliest varieties, a sheltered spot, and protection such as a cold frame or greenhouse.
How do I stop soil washing away on a slope?
Terrace the slope with low stone or timber walls, use contour beds with a ridge on the downhill edge, keep the soil covered with plants or mulch, and never leave a slope bare over winter. Raised beds also work well on slopes because each bed can be levelled individually.
Do I need a greenhouse in the mountains?
It helps a great deal, even a small one. A greenhouse or cold frame lets you start seeds early, grow tender crops, and extend the season by weeks at each end. If a greenhouse is too much, cold frames, cloches and row covers give much of the same benefit at lower cost.
Can I grow fruit in a mountain garden?
Yes — hardy fruit does well. Currants, gooseberries, raspberries, blackberries and hardy apples all tolerate cold winters. Choose late-flowering varieties where spring frosts are a risk, plant them in a sheltered spot, and protect blossom with frost cloth on cold nights.