Marjoram in USDA Zone 13 is a tender Mediterranean herb that needs the cool season to do its best work. Winter lows stay above 60°F and the zone is frost-free year-round, so there is no cold to kill it — the problem is heat and humidity, which push this soft, sweet herb to flower early and fade fast. Marjoram is closely related to oregano but gentler and sweeter, with small, soft leaves that suit soups, stews, vegetables and roasts. Grown in the coolest months, roughly November through February, with steady water and sharp drainage, it gives a generous harvest. Grown in the hot season, it struggles and bolts.
Sweet marjoram is the culinary type to look for, and it is worth knowing that it is more tender than its cousin oregano: where oregano becomes a tough perennial shrub, marjoram stays a soft, low plant that wants a kinder spot. In Zone 13 that means a pot or a sheltered, well-drained corner, planted in the cool season and enjoyed while it lasts.
Zone 13 at a glance
USDA Zone 13 is the hottest zone in the system, with average winter lows above 60°F, covering tropical places such as Puerto Rico, Hawaii and Guam. It is frost-free all year, so there is no last spring frost and no first autumn frost to plan around. Zone 13 has no frost dates to work from, so plant by heat and by the wet and dry seasons instead. These are zone averages, not promises for any one garden — check your local extension service.
| Detail | Zone 13 guidance |
|---|---|
| Winter low | Above 60°F |
| Frost | Frost-free year-round (no last or first frost dates) |
| Days to germination | 7–14 days |
| Days to maturity | 70–90 days |
| Sowing | start indoors |
| Planting window | Coolest months, roughly November–February; tender in tropical heat |
| Harvest | 70–90 days after sowing; pick leaves before flowering |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 12–18 inches |
| Water needs | low |
| Cold tolerance | tender |
When to plant marjoram in Zone 13
Plant marjoram in the coolest months, roughly November through February, so the 70–90 days to maturity fall in the mildest weather. A November sowing or planting is ready to start picking in January or February, and a well-watered plant in light shade can keep producing for a while beyond the cool season. Do not start marjoram in the hot months: it will flower early, turn bitter and finish quickly. The planting calendar hub shows the Zone 13 year, and January in Zone 13 is the heart of the marjoram window.
Starting marjoram in Zone 13
Start marjoram from seed indoors or in trays, or from a young bought plant — seed germinates in 7–14 days when kept evenly moist and warm, and seedlings grow quickly in Zone 13 warmth. Sow the tiny seed on the surface of a fine mix and barely cover it, since it needs light to germinate, and protect seedlings from pounding rain in the first week. Set young plants out once they have a few true leaves, handling the roots gently, and give them light shade in the hottest part of the day. A pot is a good home in the tropics, because you control the drainage and can move the plant to the coolest spot you have when the heat builds.
Soil, spacing, sun and water
Marjoram grows best in full sun in cooler zones, but in Zone 13 a spot with morning sun and afternoon shade gives a longer harvest before the plant flowers. It likes light, well-drained soil with a pH of 6.0–7.0, and it does not need rich soil — too much fertiliser makes soft growth that rots in humid air. Dig in a little well-rotted compost, and test the soil through your local extension service rather than guessing. Space plants 12–18 inches apart so air can move between them, using the plant spacing calculator to plan. Marjoram needs low water once established: water young plants until they root, then water only when the soil is dry, and water at the base in the morning so the soft leaves stay dry.
Companion planting
Good companions for marjoram include tomatoes, peppers, marigolds and cabbage, and marjoram is a gentle companion for vegetables, partly because its scent is said to confuse some pests. Oregano is the close cousin that shares the same dry corner but lasts longer as a perennial, and thyme grows the same way in the same sunny spot.
Pests and problems
The common pests to watch for with marjoram are aphids, spider mites and whiteflies. Inspect the soft leaves regularly, wash aphids off with a gentle jet of water, and keep the plant healthy, since spider mites attack dry, stressed plants. The pest identifier helper can help if you are unsure what you are seeing. In Zone 13, heat and humidity are the bigger threats: wet foliage invites disease, and a plant that is overwatered rots from the roots. Sharp drainage, wide spacing for airflow, morning watering at the base and light shade are the defences, and even with all of them a Zone 13 marjoram plant has a short season. Plan for that, and enjoy the leaves while they last.
Harvest and storage
Harvest marjoram by snipping sprigs from the tips, starting about 70–90 days after sowing, and pick in the morning, when the oils are strongest and the flavour is at its peak, just before the plant flowers. Take a little at a time and never strip the plant bare, since a plant that is picked regularly stays leafy longer. Use the leaves fresh the same day for the best flavour, in soups, stews and roasts. For storage, marjoram dries well: hang small bundles in a dry, airy place out of direct sun, then strip the leaves into a jar, where they keep their sweet flavour for months. When the plant flowers and fades in the heat, let it go and sow a fresh batch next cool season. Tarragon is the other tender herb that shares the same cool-season rhythm and the same morning picking routine.
Frequently asked questions
When should I plant marjoram in Zone 13?
In the coolest months, roughly November through February. A November planting is ready to start picking in about 70–90 days.
Is marjoram the same as oregano?
No, though they are close cousins.
What soil and spacing does marjoram need in Zone 13?
Morning sun and afternoon shade, light well-drained soil with a pH of 6.0–7.0, spaced 12–18 inches apart.
How do I store marjoram?
Dry it. Hang small bundles in a dry, airy place out of direct sun, then strip the leaves into a jar.