This advice is specific to Moraea and Gladiolus, but it's also good for most other bulbs that are native to a Mediterranean-style climate (no rain in summer, mild wet winter). If you live in one of those climates, it’s pretty easy to grow these plants. If you don’t live in that sort of climate, you’ll need to take some precautions to protect the plants. Don’t let me scare you away from trying them -- there are people who grow these plants successfully all over the world. Here’s what you need to know:
Contents
Summary
- Keep them dry in summer
- Use well drained soil
- Protect them from temperatures below about 20F (-6C) in winter
- When in growth, they need cool nights and sunny days. A tropical greenhouse will not work.
How to start seeds
Plant the seeds and start watering them in autumn as the weather starts to cool. In my part of California, that means the best planting time is mid- to late October.
- Many bulbs (including Moraeas) have seeds that are about the size of grains of sand. To plant these seeds, you water the soil first, and then plant the seeds 1/4 inch (6 mm) below the surface. Water gently once a week, or more often if the soil is drying out.
- Keep the soil moist but not sopping wet.
- You do not need to stratify or scratch or smoke Moraea seeds.
Q. Should I grow them in pots or a raised bed or what?
That depends on your climate:
- If you live in a mediterranean climate, you can grow them in pots, raised beds, or even in the ground if you don't have rodent problems.
- If you're not in a mediterranean climate, grow them in a way that'll let you protect the plants from weather when you need to. Usually that means growing in pots.
I started with plastic pots, but they needed to be repotted every three years, and as I got more and more bulbs it was very time consuming to repot. I am now moving everything into raised beds, because they need much less maintenance. For more about the beds, read my article here.
You can also grow these plants in open ground if you’re in a Mediterranean climate, but be aware that varmints may eat most or all of the bulbs, and weeds can out-compete them.
Q. Should I use clay or plastic pots?
In California I strongly recommend using plastic pots because clay pots dry out too quickly. I hear that in the UK clay is much better because if you use plastic the interior of the pot may never dry out at all in summer.
In California I strongly recommend using plastic pots because clay pots dry out too quickly. I hear that in the UK clay is much better because if you use plastic the interior of the pot may never dry out at all in summer.
Q. How many seeds per pot?
- For many years, I started all my bulb seeds in 16-ounce (half-liter) plastic drinking cups that had large holes drilled in the bottom for drainage. I put nine seeds to a cup.
- When I grow them in a raised bed, I start the seeds directly in the bed. I plant about 12 seeds in an 8” X 8” square space (20 cm X 20 cm).
- If I were starting them in 8-inch pots, I would use about 15 seeds per pot.
Q. How long does it take for the seeds to germinate?
Up to two months after you start watering in autumn, sometimes longer. Every year I get worried waiting for them.
Up to two months after you start watering in autumn, sometimes longer. Every year I get worried waiting for them.
In my conditions, it's risky to plant later than early December. The problem is that the seeds need a couple of months to germinate, and then after that they need to grow little bulbs to survive the first summer of dormancy. If you start them too late, they can't make big enough bulbs to survive. You might succeed if you plant later, but you risk a higher death rate of seedlings in the first summer.
Growing conditions
Q. How much light do they need?
A lot. In general they thrive with at least a half day’s full sun every day. Here in California I try to give them a bit of broken shade in the hottest part of the day, but the sun is intense here and it’s rarely overcast. If you live in a cloudy climate, that means it may be difficult to give them all the sun they need in winter.
A lot. In general they thrive with at least a half day’s full sun every day. Here in California I try to give them a bit of broken shade in the hottest part of the day, but the sun is intense here and it’s rarely overcast. If you live in a cloudy climate, that means it may be difficult to give them all the sun they need in winter.
Plants without enough sun will be slow to bloom, may produce buds that don’t open, and may get too tall and flop over.
Q. How much should I water them?
During the growing season, I water pots and beds thoroughly once a week. If there have been heavy rains during the week, I may skip the watering. The goal is to make sure the soil stays moist between waterings, but you don’t want it sopping wet.
Q. When do I stop watering?
These bulbs grow in winter and are dormant in summer. Wetness in the summer, when they are not growing, can make them rot. In my climate here in California, where they grow well, we get rain from late October until about May, and then there is usually no rain at all until next October. So around five months of total dryness in summer is normal.
Q. How will I know when to stop watering for the summer?
Let the plants tell you. The leaves will start to go yellow in early summer, June here in California. As they die back, reduce watering, and stop completely when the foliage has gone totally yellow. Sometimes seedlings will stay green for the first summer. That’s OK – keep watering them and do not force them to go dormant.
Unfortunately, other problems can also make the leaves go yellow. For example, if the roots get damaged by too much or too little water, the leaves may die back from the tip. If you get yellowing leaves in mid-winter you have probably damaged the roots. If you get yellowing leaves in late spring, they are probably going dormant.
Q. When you say they should be dry in summer, what exactly does that mean?
It means don’t water them at all and don't let rain fall on them. Here in California, where the humidity is quite low, I try to keep dormant bulb pots in shade because they could get very hot if they sat in the sun. But I do not water them at all. In moister places like the UK, I’ve been told that growers sometimes leave the pots out in the sun, under a transparent cover, because otherwise they would never dry out at all.
To make things a little more complicated, there are variations in the dryness of the mediterranean climate in South Africa. In some areas it’s normal to get a bit of rain during the summer, so some corms can tolerate a little summer water, and a few seem to expect it. But 5-6 months of dryness works OK for most of my collection.
To learn more about the various mediterranean climates, read the article I wrote for the Pacific Bulb Society here.
Q. What temperatures do they need?
While growing, the Moraeas can tolerate overnight frost down to about 20F (-6C). Lower temperatures may kill the bulbs. Even if the temperature doesn’t go below 20F, a sustained freeze over several days (enough to harden the whole pot) is also liable to kill the bulbs.
These plants expect a substantial swing between day and night temperatures in the winter. In their home climate it’s common for the temperature to go up into the 60s or 70s F on a sunny day (15-21C), and then down close to freezing at night. The seeds may not sprout if they don’t get this temperature swing. That means you can’t generally grow them in a heated greenhouse. Unheated greenhouses can work as long as they get plenty of light and the humidity level is not too high. I also know people who grow these bulbs indoors under grow lights, but once again you need to think about temperature swings.
Q. Can I leave them under the snow in winter and then have them grow in spring?
No. Unlike Tulips, they are not dormant in winter. They make their leaves and strengthen themselves in mid-winter. If you live in a snowy climate, you need to use a cold frame, greenhouse, or something similar to keep the snow off the leaves.
Q. My winter temperatures are very cold. Will the plants tolerate that?
I doubt it. I know a very skilled gardener in Colorado who tried, and he says only one bulb survived the first winter. On the other hand, there's another marvelous gardener in Colorado, Bob Nold, who says you can grow an amazing variety of things there if you use raised beds that have extremely good drainage. If you want to give it a try, go buy his out-of-print book High and Dry. It's a great read.
Repotting
Q. When do I repot the corms?
Leave them undisturbed for the first two years. Do not repot in the first dormant season, when the baby corms will be too small to handle easily. After two years, I transplant the dormant corms to pots or a raised bed so they can grow to blooming size. About six corms to an 8-inch pot is the right spacing.
Q. What time of year do I repot?
Summer only, when the corms are totally dormant.
Q. How often do I repot mature corms?
Repot when they've made enough offsets that the pot looks crowded. Usually that takes about three years if they are happy, but it varies from plant to plant.
Q. How deeply do I pot the corms?
I put them so their tops are about half an inch (1.3 cm) below the surface.
Soil
Use soil that retains moisture but drains freely. When growing in pots, I’ve been very successful with 50-50 milled peat moss and coarse sand (also known as UC Davis mix). I am told that cactus mix also works well, but it's expensive. If you have to, you can also use potting mix from your local nursery center, but don't use the cheap stuff (it may rot the bulbs), and you need to add a lot of sand to it to increase drainage.
In my raised beds, I use equal parts of pea gravel, coarse sand, and planting mix. Important: be sure the sand is washed to remove dust and fine sediment, or you won’t get enough air penetration into the soil.
Fertilizer
I add about a tablespoon (15 ml) of complete bulb fertilizer per 8-inch (20 cm) pot. In following years I give them half-strength liquid fertilizer once a month with their watering.
Q. What sort of fertilizer should I use?
If you can't get bulb fertilizer, a general-purpose fertilizer for perennials seems to work well. Be sure it contains micronutrients. Important note: I don’t use organic fertilizers – after some very bad experiences, I believe they encourage rot in bulbs.
For liquid fertilizer, I use Miracle-Gro with micronutrients.
Pests and disease
Q. Are the bulbs vulnerable to pests?
Yes:
Yes:
- Mice, rats, and voles love to dig them, and are the biggest threat
- In California, gophers are also a problem
- Slugs and snails will eat leaves and flower buds
- I also occasionally get cutworms, which emerge at night and eat the buds. I hate cutworms.
When I grow in pots, I embed a circle of half-inch chicken wire just under the surface of the pot to keep out rodents. My raised beds are lined with hardware cloth on the bottom and top of the soil. The beds are also enclosed in a frame that has window screen on the sides and shade cloth on top, to keep out insects (technically the frames are screenhouses). I use snail bait for the slugs and snails, and occasionally spray with an insecticide when the cutworms are a problem.
Q. What about disease?
Not much in my climate. When the corms are overcrowded, they'll grow very long leaves trying to outcompete each other. If it rains the leaves will get matted together and fungus can set in. You can treat this with fungicides, or cut off the ends of the leaves so they do not overlap so much. But the best remedy is to replant and thin the corms in summer.
Flowers
Q. When do they bloom?
My Moraea bulbs generally bloom between late February and early April. Some species bloom later in April. Blooming time of Gladiolus varies depending on species. Some bloom in late fall through winter, but most bloom in spring.
My Moraea bulbs generally bloom between late February and early April. Some species bloom later in April. Blooming time of Gladiolus varies depending on species. Some bloom in late fall through winter, but most bloom in spring.
Q. How long do the plants take to bloom?
Usually 3-4 years from seed. Sometimes a few of them will bloom after two years, others may take five or more years.
Q. How long do the flowers last?
Each Moraea flower lasts several days; there are a few hybrids whose flowers last a week or longer. Most of my plants have one or two branches that produce about three buds each. So that's six flowers that open one at a time. Some hybrids have more branches and more buds per branch.
Add it all up and the typical plant will be in bloom for a couple of weeks. Vigorous hybrids will bloom longer.
The Glads generally produce a single stem with two to six buds or more. They open sequentially over a few weeks.
Q. Wait, don’t go, I have another question…
Post a comment below, or drop me a note. I am glad to help.
